IDT72T51268L6-7BBG - Integrated Device Technology

DSC-6159/4

MARCH 2005

IDT72T51248

IDT72T51258

IDT72T51268

2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

40 BITS WIDE WITH FIXED 4 QUEUES

8,192 x 40 x 4, 16,384 x 40 x 4

and 32,768 x 40 x 4

IDT and the IDT logo are trademarks of Integrated Device Technology, Inc

FEATURES

••

•The multi-queue DDR flow-control device contains 4 Queues

each queue has a fixed size of:

IDT72T51248 — 8,192 x 40 or 16,384 x 20 or 32,768 x 10

IDT72T51258 — 16,384 x 40 or 32,768 x 20 or 65,536 x 10

IDT72T51268 — 32,768 x 40 or 65,536 x 20 or 131,072 x 10

••

•Write to and Read from the same queue or different queues

simultaneously via totally independent ports

••

•Up to 200MHz operating frequency or 8Gbps throughput in SDR mode

••

•Up to 100MHz operating frequency or 8Gbps throughput in DDR mode

••

•User selectable Single Data Rate (SDR) or Double Data Rate

(DDR) modes on both the write port and read port

••

•100% Bus Utilization, Read and Write on every clock cycle

••

•Global Bus Matching - All Queues have same Input bus width

and same Output bus width

••

•User Selectable Bus Matching options:

- x40in to x40out - x40in to x20out - x40in to x10out

- x20in to x40out - x20in to x20out - x20in to x10out

- x10in to x40out - x10in to x20out - x10in to x10out

••

•All I/O is LVTTL/ HSTL/ eHSTL user selectable

••

•3.3V tolerant inputs in LVTTL mode

••

•ERCLK & EREN Echo outputs on read port

FUNCTIONAL BLOCK DIAGRAM

••

•Write Chip Select WCS input for write port

••

•Read Chip Select RCS input for read port

••

•User Selectable IDT Standard mode (using EF and FF) or FWFT

mode (using IR and OR)

••

•All 4 Queues have dedicated flag outputs FF/IR, EF/OR, PAF

and PAE

••

•A Composite Full/ Input Ready Flag gives status of the queue

selected on the write port

••

•A Composite Empty/ Output Ready flag gives status of the

queue selected on the read port

••

•Programmable Almost Empty and Almost Full flags per Queue

••

•Dedicated Serial Port for flag programming

••

•A Partial Reset is provided for each queue

••

•Power Down pin minimizes power consumption

••

•2.5V Supply Voltage

••

•Available in a 324-pin Plastic Ball Grid Array (PBGA)

19mm x 19mm, 1mm Pitch

••

•JTAG port provides boundary scan function and optional

programming mode

••

•Low Power, High Performance CMOS technology

••

•Industrial temperature range (-40°°

°°

°C to +85°°

°°

°C)

Q[39:0]

x10,x20,x40

8,192 x 40

16,384 x40

32,768 x 40

8,192 x 40

16,384 x40

32,768 x 40

8,192 x 40

16,384 x40

32,768 x 40

8,192 x 40

16,384 x40

32,768 x 40

Data In

x10,x20,x40

Queue 0

Queue 1

Queue 2

Queue 3

D[39:0]

Data Out

EF0/OR0

PAE0

EF1/OR1

PAE1

EF2/OR2

PAE2

EF3/OR3

PAE3

CEF/COR

REN

RCS

RCLK

Read Control

OS[1:0]

Read Port

Flag Outputs

6159 drw01

FF0/IR0

PAF0

FF1/IR1

PAF1

FF2/IR2

PAF2

FF3/IR3

PAF3

Write Port

Flag Outputs

CFF/CIR

WEN

WCS

WCLK

Write Control

IS[1:0]

MULTI-QUEUE DDR FLOW-CONTROL DEVICE

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

Table of Contents

Features .........................................................................................................................................................................................................................1

Description ......................................................................................................................................................................................................................3

Pin Configuration .............................................................................................................................................................................................................5

Pin Descriptions............................................................................................................................................................................................................6-8

Device Characteristics .....................................................................................................................................................................................................9

DC Electrical Characteristics ..........................................................................................................................................................................................10

AC Electrical Characteristics........................................................................................................................................................................................... 11

AC T est Conditions ........................................................................................................................................................................................................ 12

Functional Descriptions.............................................................................................................................................................................................14-22

Signal Descriptions ...................................................................................................................................................................................................23-28

JTAG Timing Specifications .......................................................................................................................................................................................29-33

List of Tables

T able 1 — Device Configuration ....................................................................................................................................................................................14

Table 2 — Default Programmable Flag Offsets................................................................................................................................................................14

Table 3 — Status Flags for IDT Standard Mode............................................................................................................................................................. 17

Table 4 — Status Flags for FWFT Mode ........................................................................................................................................................................17

Table 5 — I/O V oltage Level Configuration..................................................................................................................................................................... 18

Table 6 — TSKEW Measurement .................................................................................................................................................................................. 27

List of Figures

Figure 1. Multi-Queue DDR Flow-Control Device Block Diagram....................................................................................................................................4

Figure 2a. AC Test Load................................................................................................................................................................................................12

Figure 2b. Lumped Capacitive Load, Typical Derating ...................................................................................................................................................12

Figure 3. Programmable Flag Offset Programming Methods ........................................................................................................................................... 15

Figure 4. Offset Registers Serial Bit Sequence................................................................................................................................................................ 16

Figure 5. Bus-Matching Byte Arrangement................................................................................................................................................................19-21

Figure 6. Echo Read Clock and Data Output Relationship ..............................................................................................................................................28

Figure 7. Standard JT AG Timing...................................................................................................................................................................................29

Figure 8. JT AG Architecture ...........................................................................................................................................................................................30

Figure 9. T AP Controller State Diagram .........................................................................................................................................................................31

Figure 10. Master Reset Timing.....................................................................................................................................................................................34

Figure 1 1. Partial Reset Timing ......................................................................................................................................................................................35

Figure 12. Write Cycle and Full Flag Timing (IDT Standard mode, SDR to SDR, x40 In to x40 Out)...............................................................................36

Figure 13. Write Cycle and Full Flag Timing in DDR mode ( IDT Standard mode, DDR to DDR, x40 In to x40 Out) ......................................................37

Figure 14. Write Cycle and Full Flag Timing with bus-matching and rate matching (IDT Standard mode, DDR to SDR, x10 In to x20 Out) .....................38

Figure 15. Write Cycle and Full Flag Timing with rate matching (IDT Standard mode, SDR to DDR, x40 In to x40 Out) .................................................39

Figure 16. Write Timing in FWFT mode (FWFT mode, SDR to SDR, x40 In to x40 Out).................................................................................................40

Figure 17. Write Cycle and First Word Latency Timing in DDR mode (FWFT mode, DDR to DDR, x40 In to x40 Out)....................................................41

Figure 18. Read Cycle, Empty Flag & First Word Latency (IDT Standard mode, SDR to SDR, x40 In to x40 Out)..........................................................42

Figure 19. Read Cycle, Empty Flag & First Word Latency in DDR mode (IDT Standard mode, DDR to DDR, x40 In to x40 Out) ...................................43

Figure 20. Read Cycle, Empty Flag & First Word Latency w/ bus-matching and rate-matching (IDT Standard mode, DDR to SDR, x40 In to x20 Out) ...44

Figure 21. Read Cycle and Empty Flag Timing with bus-matching and rate-matching (IDT Standard mode, SDR to DDR, x10 In to x20 Out) ................45

Figure 22. Read Timing at Full Boundary (FWFT mode, SDR to SDR, x40 In to x40 Out) .............................................................................................46

Figure 23. Composite Empty Flag (IDT Standard mode, SDR to SDR, x40 In to x40 Out) ..............................................................................................47

Figure 24. Composite Output Ready Flag (FWFT mode, SDR to SDR, x40 In to x40 Out) .............................................................................................47

Figure 25. Composite Full Flag (IDT Standard mode, SDR to SDR, x40 In to x40 Out).................................................................................................. 48

Figure 26. Composite Input Ready Flag (FWFT mode, SDR to SDR, x40 In to x40 Out)................................................................................................48

Figure 27. Queue Switch at Every Clock Cycle (IDT Standard mode, SDR to SDR, x40 In to x40 Out).......................................................................... 49

Figure 28. Echo Read Clock and Read Enable Operation (IDT Standard mode, SDR to SDR, x40 In to x40 Out)..........................................................50

Figure 29. Echo RCLK and Echo Read Enable Operation (FWFT mode, SDR to SDR, x40 In to x40 Out) ....................................................................51

Figure 30. Echo Read Clock and Read Enable Operation (IDT Standard mode, DDR to DDR, x10 In to x10 Out).........................................................52

Figure 31. Loading of Programmable Flag Registers (IDT Standard and FWFT modes) ................................................................................................53

Figure 32. Reading of Programmable Flag Registers (IDT Standard and FWFT modes)................................................................................................ 53

Figure 33. Synchronous Programmable Almost-Full Flag Timing (IDT Standard and FWFT mode, SDR to SDR, x40 In to x40 Out) ..............................54

Figure 34. Synchronous Programmable Almost-Empty Flag Timing (IDT Standard and FWFT mode, SDR to SDR, x40 In to x40 Out)...........................54

Figure 35. Power Down Operation................................................................................................................................................................................ 55

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

DESCRIPTION

The multi-queue DDR flow-control devices are ideal for many applications

where functions such as data differentiation and parallel buffering of multiple data

paths are required. These applications may include communication and

networking systems such as routers, packet prioritization systems, data acqui-

sition systems, imaging systems and medical equipment.

The IDT72T51248/72T51258/72T51568 multi-queue DDR flow-control

devices are a single chip with four discrete FIFO queues available. All four

queues have a fixed density and based on the bus matching arrangement can

take the following memory arrangement: For the IDT72T51248, four queues

each queue being 8,192 x40 or 16,384 x20 or 32,768 x10. For the

IDT72T51258, four queues each queue being 16,384 x40 or 32,768 x20 or

65,536 x10. For the IDT72T51268, four queues each queue being 32,768 x40

or 65,536 x20 or 131,072 x10.

All queues within the device have a common data input bus (write port) and

a common data output bus (read port). Data written into the write port is directed

to a respective queue via an internal de-multiplex operation, the queue being

address by the user via a two bit input select bus. Data read from the read port

is accessed from a respective queue via an internal multiplex operation,

addressed by the user via a two bit output select bus. Data write and read

operations are totally independent of each other, a queue may be selected on

the write port and a different queue selected on the read port, or both ports may

select the same queue simultaneously.

Bus matching is provided on this device, the bus width selection is 'Global'

which means that all four queues will have a fixed input width and a fixed output

width. The write port bus width may be x10, x20 or x40 and the read port bus

width may be x10, x20 or x40. When bus matching is used the device ensures

the logical transfer of data throughput in a Little Endian manner.

As is typical with most IDT FIFO’s, two types of data transfer are available,

IDT Standard mode and First word Fall Through (FWFT) Mode. This affects

the device operation and also the flag outputs. The device provides four

dedicated flag outputs for all internal Queue’s. These flags are: Full/ Input Ready

flag, Empty/ Output Ready flag, Programmable Almost Empty flag and Program-

mable Almost Full. The programmable flags have default values, but can also

be set by the user to any point within the Queue depth. These programmable

flags can also be configured by the user for either Synchronous or Asynchro-

nous operation. The device also provides composite flags.

The multi-queue DDR device offers a maximum throughput of 8Gbps, with

selectable SDR or DDR data transfer modes for the inputs and outputs. In SDR

mode, the input clock can operate up to 200MHz. Data will transition/latch on

the rising edge of the clock. In DDR mode, the input clock can operate up to 100

MHz, with data transitioning/latched on both rising and falling edges of the clock.

The advantage of DDR is that it can achieve the same throughput as SDR with

only half the number of bits, assuming the frequency is constant. For example,

a 4Gbps throughput in SDR is 100MHz x 40 bits. In DDR mode, it is 100MHz

x 20 bits, because two bits transition per clock cycle.

The read port provides the user with a dedicated Echo Read Enable, EREN

and Echo Read Clock, ERCLK output. These outputs are helpful in higher speed

applications. Otherwise known as “Source Synchronous clocking” the echo

outputs provide tighter synchronization of the data transmitted from the multi-

queue flow-control device and the read clock being received at the down-

stream device.

A Master Reset input is provided and all set-up and configuration pins are

latched with respect to a Master Reset. For example, the bus width requirements

are selected at Master Reset. A Partial Reset is provided for each internal

Queue. When a Partial Reset is performed on a Queue, the read and write

pointers of that Queue only are reset to the first memory location. All other pointers

remain the same.

The device also has the capability of operating its I/O at either 2.5V LVTTL,

1.5V HSTL or 1.8V eHSTL levels. A Voltage Reference, VREF input is provided

for HSTL and eHSTL interfaces. The type of I/O is selected via the IOSEL pin.

The core supply voltage of the device, VCC is always 2.5V, however the output

pins have a separate supply, VDDQ which can be 2.5V, 1.8V or 1.5V. The device

also offers significant power savings in HSTL/eHSTL mode, most notably

achieved by the presence of a Power Down input, PD.

A JTAG test port is provided. The multi-queue DDR device has a fully

functional Boundary Scan feature, compliant with IEEE 1149.1 Standard Test

Access Port and Boundary Scan Architecture. The JTAG port can also be used

to program the device set-up as described later in this document.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

INPUT

DEMUX

4 Identical

FIFO

Queues

1.3Mbit

Dual Port

Memory

x10, x20, x40

Write Control

Logic

WEN WCS

WCLK

Write Port

Flag Outputs

D0 - D39

Din

IS[1:0]

WDDR

FF0/IR0

PAF0

FF1/IR1

PAF1

FF2/IR2

PAF2

FF3/IR3

PAF3

CFF/CIR

Write Pointer

Bus

Configuration

IW[1:0]

OW[1:0]

HSTL I/O

Control

IOSEL

REF

x10, x20, x40

Qout

OUTPUT

Q0 - Q39

6159 drw02

OUTPUT

MUX

MRS

Reset Logic

PRS0

PRS1

PRS2

PRS3

SCLK

Flag Offset

Programming

SWEN

SREN

FWFT/SI

SDO

JTAG Control

(Boundary Scan)

TCK

TRST

TMS

TDI

TDO

RCLK

REN

Read Control

Logic

Read Pointer

RDDR

ERCLK

EREN

Read Port

Flag Outputs

and

Control Logic

EF0/OR0

PAE0

EF1/OR1

PAE1

EF2/OR2

PAE2

EF3/OR3

PAE3

CFF/COR

FSEL[1:0]

OS[1:0]

RCS

Figure 1. Multi-Queue DDR Flow-Control Device Block Diagram

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

GND

D39 Q33

Q36

FF2 PAF3 OS0 Q35V

DDQ

GND V

DDQ

D0 D1

D13

WCLK

GND

D38

GND

GND GND

GND

PRS0

GND

DDQ

PRS3

REF

MRS

D23

FWFT/SI

Q12

Q15

12 34 56 78910111213141516

A1 BALL PAD CORNER

OW1

D24

D27

D30

D33

D36

GND

DDQ

GND

D26

D29

D32

D35

D11

D14

D16

D18

D20

D25

D22

D28

D31

D34

D37 Q30

Q18

DNC

Q21

Q24

Q27

TDI SREN

SCLK

D12

D15

D17

D19

D21

D4 D5 FSEL0

WDDR

D9 OW0

FSEL1 V

DDQ

IW0 GND

TRST

IW1 TMS

TCK

GND

IOSEL V

DDQ

GND GND

DDQ

SWEN

D10

RDDR V

PRS1 PRS2

6159 drw03

IS1

GND

Q38

GND

EF3 OS1 V

GNDGNDV

RCS

PAE3 V

FF3 V

REN

17 18

ERCLK

DNC

Q37

Q34

Q10

Q13

Q32

Q16

Q19

Q20

Q23

Q26

Q29

TDO

SDO

EREN

DNC

Q22

Q25

Q28

Q31

Q11

Q14

Q17

DNC

RCLK

Q39

DDQ

GND

DDQ

GNDGND

GNDGND GND

GND GND V

DDQ

GND

GNDGND

GNDGND GND

GND GND V

DDQ

GND

GND GND

GND

GND GND GND GND V

DDQ

GND

GND GND

GND V

DDQ

GNDV

DDQ

GND V

DDQ

GNDGND

GND V

DDQ

GND

GND V

DDQ

GND

GND V

DDQ

GND

GND V

DDQ

GND

WEN V

WCS V

IS0 PAE0 EF0 PAE1 FF1 PAE2

PAF0 EF1 CEF EF2

FF0 PAF1 CFF PAF2

PBGA: 1mm Pin Pitch, 19mm x 19mm (BB324-1, order code: BB)

TOP VIEW

PIN CONFIGURATION

NOTE:

1. DNC - Do Not Connect.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

CEF/COR Composite Empty/ HSTL-LVTTL This flag will represent the exact status of the current Queue being read without the user having to

Composite Output OUTPUT observe the correct Queue empty flag.

Ready Flag

CFF/CIR Composite Full/ HSTL-LVTTL This flag will represent the exact status of the current Queue being written without the user having to

Composite Input OUTPUT observe the correct Queue full flag.

Ready flag

D[39:0] Data Input Bus LVTTL These are the 40 data input pins. Data is written into the device via these input pins on the rising edge

Din INPUT of WCLK and/or the falling edge in DDR mode provided WEN is LOW. Due to bus-matching not all

inputs may be used, any unused inputs should be tied to LOW.

EF0/OR0 Empty Flags 0/1/2/3 HSTL-LVTTL These are the Empty Flag (Standard IDT mode) or Output Ready Flag (FWFT mode) outputs for the

EF1/OR1, or Output Ready OUTPUT read port of Queue 0, 1, 2 and 3 respectively.

EF2/OR2, Flags 0/1/2/3

EF2/OR3

ERCLK Echo Read Clock HSTL-LVTTL This is the echo clock output for the read port. It is synchronous to the data output bus Q[35:0] and

OUTPUT the input RCLK.

EREN Echo Read Enable HSTL-LVTTL This is the echo read enable output for the read port.

OUTPUT Echo Read Enable is synchronous to the RCLK input and is active when a read operation has occurred

and a new word has been placed onto the data output bus.

FF0/IR0, Full Flags 0/1/2/3 HSTL-LVTTL These are the Full Flag (Standard IDT mode) or Input Ready Flag (FWFT mode) outputs for the write

FF1/IR1, or Input Ready OUTPUT port of Queue 0, 1, 2 and 3 respectively.

FF2/IR2, Flags 0/1/2/3

FF3/IR3

FSEL Flag Select HSTL-LVTTL Flag select default offset pins. During Master reset, the FSEL pins are used to select one of 4 default

[1:0] INPUT PAE and PAF offsets. Both the PAE and the PAF offsets are programmed to the same value.

Values are: 00 = 7; 01 = 63; 10 = 127; 11 = 1023, meaning all four Queues have the same offset.

FWFT/SI First Word Fall HSTL-LVTTL During Master Reset, FWFT=1 selects First Word Fall Through mode, FWFT=0 selects IDT Standard

Through/ Serial INPUT mode. After Master Reset this pin is used for the Serial Data input for the programming of the PAE and

Input PAF flags offset registers.

IOSEL I/O Select CMOS During Master Reset if the IOSEL pin is HIGH, then all inputs and outputs that are designated “LVTTL

INPUT or HSTL” will be set to HSTL. If LOW then they will be set to LVTTL. All pins with a CMOS format

will remain unchanged. CMOS format means that the pin is intended to be tied to VCC or GND and

these particular pins are not tested for VIL or VIH.

IS[1:0] Input Select HSTL-LVTTL These inputs select one of the four Queue’s to be written into on the write port. The address on the

INPUT input select pins is set-up with respect to the WCLK.

IW[1:0] Input Width CMOS This pin is used during Master Reset to select the input word width bus size for the device. 00 = x10;

INPUT 01 = x20; 10 = x40

MRS Master Reset HSTL-LVTTL This input provides a full device reset. All configuration pins are sampled based on a Master Reset

INPUT operation.

OE Output Enable HSTL-LVTTL This is the Output Enable for the read port. The data outputs will be placed into High Impedance if

INPUT this pin is HIGH. This input is asynchronous.

OS[1:0] Output Select HSTL-LVTTL These inputs select one of the four Queue’s to be read from on the read port. The address on the

INPUT output select pins is set-up with respect to the RCLK.

OW[1:0] Output Width CMOS This pin is used during Master Reset to select the output word width bus size for the device. 00 = x10;

INPUT 01 = x20; 10 = x40

PAE0, PAE1 Programmable HSTL-LVTTL These are the Programmable Almost Empty Flag outputs for the read port of Queue 0, 1, 2 and 3

PAE2, PAE3 Almost Empty OUTPUT respectively.

Flags 0/1/2/3

PIN DESCRIPTIONS

Symbol Name I/O TYPE Description

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

PAF0, PAF1 Programmable HSTL-LVTTL These are the Programmable Almost Full Flag outputs for the write port of Queue 0, 1, 2 and 3

PAF2, PAF3 Almost Full OUTPUT respectively.

Flags 0/1/2/3

PD Power Down HSTL-LVTTL This input provides considerable power saving in HSTL/eHSTL mode. If this pin is low, the input

INPUT level translators for all the data input pins, clocks and non-essential control pins are turned off. When

PD is brought high, a power-up sequence timing will have to be met before the inputs will be read.

It is essential that the user respects these conditions when powering down the part and powering up

the part, so as to not produce runt pulses or glitches on the clocks if the clocks are free running.

PRS0, PRS1 Partial HSTL-LVTTL These are the Partial Reset inputs for each internal Queue. Resets the read and write and the flag

PRS2, PRS3 Reset 0/1/2/3 INPUT pointers to zero, sets the output register to zero. During Partial Reset, the existing mode (IDT or FWFT)

and the programmable flag settings are all retained.

Q[39:0](2) Data Output Bus LVTTL These are the 40 data output pins. Data is read out of the device via these output pins on the rising

OUTPUT edge of RCLK provided that REN is LOW, OE is LOW and the queue is selected. Due to bus-matching

not all outputs may be used, any unused outputs should not be connected.

RCLK Read Clock HSTL-LVTTL This is the clock input for the read port. All read port operations will be synchronous to this clock input.

INPUT

RCS Read Chip Select HSTL-LVTTL This is the read chip select input for the read port. All read operations will occur synchronous to the

INPUT RCLK clock input provided that REN and RCS are LOW. When RCS is HIGH the outputs are in high-

impedance and reads are disabled.

RDDR Read Port DDR CMOS During master reset, this pin selects DDR or SDR format. If RDDR=1, then the RCLK reads a word

INPUT on both the rising and falling edge of RCLK. If RDDR=0 then the RCLK reads a word only on the

rising edge of RCLK.

REN Read Enable HSTL-LVTTL This is the read enable input for the read port. All read operations will occur synchronous to the RCLK

INPUT clock input provided that REN and RCS are LOW.

SCLK Serial Clock HSTL-LVTTL Serial clock for programming and reading the PAE and PAF offset registers. On the rising edge of each

INPUT SCLK, when SWEN is low, one bit of data is shifted into the PAE and PAF registers. On the rising edge

of each SCLK, when SREN is low, one bit of data is shifted out of the readback PAE and PAF registers.

The reading of the PAE and PAF registers is non-destructive.

SDO Serial Data Output HSTL-LVTTL When SREN is brought low before the rising edge of SCLK, the contents of the PAE and PAF

OUTPUT registers are copied to a readback serial register. While SREN is maintained low, on each rising

edge of SCLK, one bit of data is shifted out of this readback register through the SDO output pin.

SREN Serial Read Enable HSTL-LVTTL When SREN is brought low before the rising edge of SCLK, the contents of the PAE and PAF

INPUT registers are copied to a readback serial register. While SREN is maintained low, on each rising

edge of SCLK, one bit of data is shifted out of this readback register through the SDO output pin.

SWEN Serial Write Enable HSTL-LVTTL On each rising edge of SCLK when SWEN is low, data from the FWFT/SI pin is serially loaded

INPUT into the PAE and PAF registers. Each bit loaded into the registers go directly to the PAE/PAF

registers and the new flags will be in operation.

TCK(3) JTAG Clock HSTL-LVTTL Clock input for JTAG function. One of four terminals required by IEEE Standard 1149.1-1990. Test

INPUT operations of the device are synchronous to TCK. Data from TMS and TDI are sampled on the

rising edge of TCK and TDO change on the falling edge of TCK. If the JTAG function is not used

this signal needs to be tied to GND.

TDI(3) JTAG Test Data HSTL-LVTTL One of four terminals required by IEEE Standard 1149.1-1990. During the JTAG boundary scan

Input INPUT operation, test data is serially scanned to the TDI on the rising edge of TCK to the Instruction

forces TDI HIGH if left unconnected.

TDO(3) JTAG Test Data HSTL-LVTTL One of four terminals required by IEEE Standard 1149.1-1990. During the JTAG boundary scan

Output OUTPUT operation, test data is serially loaded via the TDO on the falling edge of TCK from either the Instruction

except when shifting, while in SHIFT-DR and SHIFT-IR controller states.

PIN DESCRIPTIONS (CONTINUED)

Symbol Name I/O TYPE Description

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

TMS(3) JTAG Mode Select HSTL-LVTTL TMS is a serial input pin. One of four terminals required by IEEE Standard 1149.1-1990. TMS directs

INPUT the device through its TAP controller states sampled on the rising edge of TCK. An internal pull-up

resistor forces TMS HIGH if left unconnected.

TRST(3) JTAG Reset HSTL-LVTTL TRST is an asynchronous reset pin for the JTAG controller. The JTAG TAP controller is automatically

INPUT reset upon power-up. If the TAP controller is not properly reset then the Queue outputs will always

be in high-impedance. If the JTAG function is used but the user does not want to use TRST, then TRST

can be tied with MRS to ensure proper Queue operation. If the JTAG function is not used then this

signal needs to be tied to GND. An internal pull-up resistor forces TRST HIGH if left unconnected.

WCLK Write Clock HSTL-LVTTL This is the clock input for the write port. All write port operations will be synchronous to this clock input

INPUT on either the rising edge (SDR mode) or rising or falling edge (DDR mode).

WCS Write Chip Select HSTL-LVTTL This is the write chip select input for the write port. All write operations will occur synchronous to the

INPUT WCLK clock input provided that WEN and WCS are LOW, sampled on WCLK.

WDDR Write Port DDR CMOS During master reset, this pin selects DDR or SDR format. If WDDR=1, then the WCLK writes a word

INPUT on both the rising and falling edge. If WDDR=0 then the WCLK writes a word only on the rising edge.

WEN Write Enable HSTL-LVTTL This is the write enable input for the write port. All write operations will occur synchronous to the WCLK

INPUT clock input provided that WEN and WCS are LOW, sampled on the rising edge of WCLK.

VCC +2.5 Supply P W R Power supply for the chip core, 2.5V.

VDDQ Output Rail Voltage PWR Power supply for all of the chip’s outputs. 2.5V for LVTTL outputs, 1.5V for HSTL outputs or 1.8V for

eHSTL outputs.

GND Ground Pin GND Ground connection.

VREF Reference voltage Analog Voltage Reference input for HSTL inputs.

PIN DESCRIPTIONS (CONTINUED)

Symbol Name I/O TYPE Description

NOTES:

1. All CMOS pins should remain unchanged. CMOS format means that the pin is intended to be tied directly to VCC or GND and these particular pins are not tested for VIH

or VIL.

2. All unused outputs should be left un-connected.

3. These pins are for the JTAG port. Please refer to pages 29-33, Figure 7-9 for JTAG information.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

ABSOLUTE MAXIMUM RATINGS

NOTES:

1 . Stresses greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause

permanent damage to the device. This is a stress rating only and functional operation

of the device at these or any other conditions above those indicated in the operational

sections of this specification is not implied. Exposure to absolute maximum rating

conditions for extended periods may affect reliability.

2. Compliant with JEDEC JESD8-5. VCC terminal only.

Symbol Parameter(1) Conditions Max. Unit

CIN(2,3) Input VIN = 0V 10(3) pF

Capacitance

COUT(1,2) Output VOUT = 0V 10 pF

Capacitance

CAPACITANCE (TA = +25°C, f = 1.0MHz)

NOTES:

1. With output deselected, (OE ≥ VIH).

2. Characterized values, not currently tested.

3. CIN for Vref is 20pF.

Symbol Parameter Min. Typ. Max. Unit

VCC Supply Voltage with reference to GND 2.375 2.5 2.625 V

VDDQ Output Supply Voltage  LVTTL 2.375 2.5 2.625 V

 eHSTL 1. 7 1. 8 1. 9 V

 HSTL(2) 1.4 1.5 1.6 V

VREF Voltage Reference Input  eHSTL 0. 8 0. 9 1. 0 V

 HSTL(2) 0.68 0.75 0.9 V

VIH Input High Voltage  LVTTL 1.7 — 3.45 V

 eHSTL VREF+0.1 — VDDQ+0.3 V

 HSTL(2) VREF+0.1 — VDDQ+0.3 V

VIL Input Low Voltage  LVTTL — — 0.7 V

 eHSTL -0.3 — VREF-0.1 V

 HSTL(2) -0.3 — VREF-0.1 V

TAOperating Temperature Commercial 0 — +70 °C

TAOperating Temperature Industrial -40 — +85 °C

RECOMMENDED DC OPERATING CONDITIONS

NOTES:

1. VREF is only required for HSTL or eHSTL inputs. VREF should be tied LOW for LVTTL operation.

2. Compliant with JEDEC JESD8-6.

3. GND = Ground.

Symbol Rating Com'l & Ind'l Unit

VTERM Terminal Voltage –0.5 to +3.6(2) V

with respect to GND

TSTG Storage Temperature –55 to +125 °C

IOUT DC Output Current –50 to +50 mA

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

DC ELECTRICAL CHARACTERISTICS

(Industrial: VCC = 2.5V ± 0.125V, T A = -40°C to +85°C)

Symbol Parameter Min. Max. Unit

ILI Input Leakage Current –10 +10 µA

ILO Output Leakage Current –10 +10 µA

VOH(7) Output Logic “1” Voltage, IOH = –8 mA @LVTTL V DDQ -0.4 — V

IOH = –8 mA @eHSTL VDDQ -0.4 — V

IOH = –8 mA @HSTL VDDQ -0.4 — V

VOL Output Logic “0” Voltage, IOL = 8 mA @LVTTL — 0. 4 V

IOL = 8 mA @eHSTL — 0.4 V

IOL = 8 mA @HSTL — 0.4 V

ICC(1,2,3) Active VCC Current -- LVTTL — 200(6) mA

(See Note 8 for test conditions) -- eHSTL — 260(6) mA

-- HSTL — 26 0(6) mA

IDDQ(1,2,3) Active VDDQ Current -- LVTTL — 20 mA

(See Note 8 for test conditions) -- eHSTL — 8 mA

-- HSTL — 8 mA

ISB1(1,2,3) Standby VCC Current -- LVTTL — 120(6) mA

(See Note 9 for test conditions) -- eHSTL — 190(6) mA

-- HSTL — 19 0(6) mA

ISB2(1,2,3) Standby VDDQ Current -- LVTTL — 15 mA

(See Note 9 for test conditions) -- eHSTL — 8 mA

-- HSTL — 8 mA

IPD1(1,2,3) Power Down VCC Current -- LVTTL — 15(6) mA

(See Note 10 for test conditions) -- eHSTL — 30(6) mA

-- HSTL — 3 0(6) mA

IPD2(1,2,3) Power Down VDDQ Current -- LVTTL — 0.5 mA

(See Note 10 for test conditions) -- eHSTL — 0.5 mA

-- HSTL — 0. 5 mA

NOTES:

1. Both WCLK and RCLK toggling at 20MHz.

2. Data inputs toggling at 10MHz.

3. Typical ICC1 calculation:for LVTTL I/O ICC1 (mA) = 6 x fs, fs = WCLK frequency = RCLK frequency (in MHz)

for HSTL or eHSTL I/O ICC1 (mA) = 90+ (6 x fs), fs = WCLK frequency = RCLK frequency (in MHz)

4. Typical IDDQ calculation: With Data Outputs in High-Impedance: IDDQ (mA) = 0.25 x fs, fs = WCLK = RCLK frequency (in MHz)

With Data Outputs in Low-Impedance: IDDQ (mA) = (CL x VDDQ x fs x N) /2000

fs = WCLK frequency = RCLK frequency (in MHz), VDDQ = 2.5V for LVTTL; 1.5V for HSTL; 1.8V for eHSTL

tA = 25°C, CL = capacitive load (pF), N = Number of bits switching

5. Total Power consumed: PT = [(VCC x ICC) + (VDDQ x IDDQ)]. IOH = -8mA for all voltage levels.

6. Maximum value tested wtih RCLK = WCLK = 20MHz at 85°C. Maximum value may differ depending on VCC and temperature.

7. Outputs are not 3.3V tolerant.

8. VCC = 2.5V, WCLK = RCLK = 20MHz, WEN = REN = LOW, WCS = RCS = LOW, OE = LOW, PD = HIGH.

9. VCC = 2.5V, WCLK = RCLK = 20MHz, WEN = REN = HIGH, WCS = RCS = HIGH, OE = LOW, PD = HIGH.

10. VCC = 2.5V, WCLK = RCLK = 20MHz, WEN = REN = HIGH, WCS = RCS = HIGH, OE = LOW, PD = LOW.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

AC ELECTRICAL CHARACTERISTICS(1)

(Commercial: VCC = 2.5V ± 0.15V, TA = 0°C to +70°C;Industrial: VCC = 2.5V ± 0.15V, TA = -40°C to +85°C; JEDEC compliant)

Commercial Commercial & Industrial

IDT72T51248L5 IDT72T51248L6-7

IDT72T51258L5 IDT72T51258L6-7

IDT72T51268L5 IDT72T51268L6-7

Symbol Parameter Min. Max. Min. Max. Unit

fS1 Clock Cycle Frequency (WCLK & RCLK) SDR — 200 — 150 MHz

fS2 Clock Cycle Frequency (WCLK & RCLK) DDR — 100 — 75 MHz

tAData Access Time 0.6 3.6 0.6 3.8 ns

tCLK1 Clock Cycle Time SDR 5 — 6.7 — ns

tCLK2 Clock Cycle Time DDR 10 — 13 — ns

tCLKH1 Clock High Time SDR 2.3 — 2.8 — ns

tCLKH2 Clock High Time DDR 4.5 — 6.0 — ns

tCLKL1 Clock Low Time SDR 2.3 — 2.8 — ns

tCLKL2 Clock Low Time DDR 4.5 — 6.0 — ns

tDS Data Setup Time 1.5 — 2.0 — ns

tDH Data Hold Time 0.5 — 0.5 — ns

tENS Enable Setup Time 1.5 — 2.0 — ns

tENH Enable Hold Time 0.5 — 0.5 — ns

fCClock Cycle Frequency (SCLK) — 10 — 10 MHz

tASO Serial Output Data Access Time — 20 — 20 ns

tSCLK Serial Clock Cycle 100 — 100 — ns

tSCKH Serial Clock High 45 — 45 — ns

tSCKL Serial Clock Low 45 — 45 — ns

tSDS Serial Data In Setup 15 — 15 — n s

tSDH Serial Data In Hold 5 — 5 — n s

tSENS Serial Enable Setup 5 — 5 — n s

tSENH Serial Enable Hold 5 — 5 — ns

tRS Reset Pulse Width 200 — 200 — ns

tRSS Reset Setup Time 15 — 15 — ns

tRSR Reset Recovery Time 10 — 10 — ns

tRSF Reset to Flag and Output Time — 12 — 15 ns

tOLZ (OE - Qn)(2) Output Enable to Output in Low-Impedance 0.6 3.6 0.8 3.8 ns

tOHZ(2) Output Enable to Output in High-Impedance 0. 6 3 .6 0.8 3 .8 n s

tOE Output Enable to Data Output Valid 0 .6 3 . 6 0 . 8 3 . 8 n s

tWFF Write Clock to FF or IR — 3.6 — 3.8 ns

tREF Read Clock to EF or OR — 3.6 — 3.8 ns

tCEF Read Clock to Composite EF or OR — 3.6 — 3.8 ns

tCFF Write Clock to Composite FF or IR — 3.6 — 3.8 ns

tPAFS Write Clock to Synchronous Programmable Almost-Full Flag — 3.6 — 3.8 ns

tPAES Read Clock to Synchronous Programmable Almost-Empty Flag — 3.6 — 3.8 ns

tPAFA Write Clock to Asynchronous Programmable Almost-Full Flag — 10 — 12 ns

tPAEA Read Clock to Asynchronous Programmable Almost-Empty Flag — 10 — 12 ns

tERCLK RCLK to Echo RCLK Output — 4.0 — 4.3 ns

tCLKEN RCLK to Echo REN Output — 3. 6 — 3 .8 n s

tDTime Between Data Switching and ERCLK edge 0.4 — 0.5 — ns

tRCSLZ RCLK to Active from High-Impedance — 3.6 — 3.8 ns

tRCSHZ RCLK to High-Impedance — 3.6 — 3.8 ns

tSKEW1 SKEW time between RCLK and WCLK for EF/OR and FF/IR 4— 5—ns

tSKEW2 SKEW time between RCLK and WCLK for EF/OR and FF/IR in5— 7—ns

DDR mode

tSKEW3 SKEW time between RCLK and WCLK for PAE and PAF 5— 7—ns

NOTES:

1. With exception to clock cycle frequency, these parameters apply to both DDR and SDR modes of operation.

2. Values guaranteed by design, not currently tested.

3. Industrial temperature range product for the 6-7ns speed grade is available as a standard device. All other speed grades available by special order.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

AC TEST LOADS

Figure 2a. AC Test Load

6159 drw04

Ω

DDQ

I/O Z

= 50

Ω

10pF

Input Pulse Levels 0.25 to 1.25V

Input Rise/Fall Times 0.4ns

Input Timing Reference Levels 0.75V

Output Reference Levels 0.75V

HSTL

1.5V AC TEST CONDITIONS

Input Pulse Levels GND to 2.5V

Input Rise/Fall Times 1ns

Input Timing Reference Levels 1.25V

Output Reference Levels 1.25V

LVTTL

2.5V AC TEST CONDITIONS

NOTE:

1. VDDQ = 1.5V.

NOTE:

1. For LVTTL, VCC = VDDQ = 2.5V.

Input Pulse Levels 0.4 to 1.4V

Input Rise/Fall Times 0.4ns

Input Timing Reference Levels 0.9V

Output Reference Levels 0.9V

EXTENDED HSTL

1.8V AC TEST CONDITIONS

NOTE:

1. VDDQ = 1.8V.

Figure 2b. Lumped Capacitive Load, Typical Derating

6159 drw04a

20 30 50 80 100 200

Capacitance (pF)

∆tCD

(Typical, ns)

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

OUTPUT ENABLE & DISABLE TIMING

tOE & tOLZ

100mV

tOHZ

100mV

Single Output

Normally

LOW

Single Output

Normally

HIGH

VDDQ/2

6159 drw05

Output

Enable

Output

Disable

VDDQ/2

OLZ

Current data in output register

tOE

VDDQ/2

Output Bus VDDQ/2

tOHZ

READ CHIP SELECT ENABLE & DISABLE TIMING

NOTES:

1. REN is HIGH.

2. OE is LOW.

RCS

ENS

ENH

RCSLZ

RCLK

DDQ

100mV

RCSHZ

100mV

Single Output

Normally

LOW

Single Output

Normally

HIGH

DDQ

6158 drw06

Output Bus

Current data in output register

DDQ

NOTES:

1. REN is HIGH.

2. RCS is LOW.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

FUNCTIONAL DESCRIPTIONS

MASTER RESET & DEVICE CONFIGURATION - MRS

During Master Reset the device configuration and settings are determined,

this includes the following:

1. IDT Standard or First Word Fall Through (FWFT) flag timing mode

2. Single or Double Data Rates on both the Write and Read ports

3. Programmable flag mode, synchronous or asynchronous timing

4. Write and Read Port Bus Widths, x40, x20, or x10

5. Default Offsets for the programmable flags, 7, 63, 127, or 1023

6. LVTTL or HSTL I/O selection

7. Default starting Queue

The state of the configuration inputs during master reset will determine which

of the above modes are selected. A master reset comprises of pulsing the MRS

input pin from high to low for a period of time (tRS) with the configuration inputs

held in their respective states. Table 1 summarizes the configuration modes

available during master reset. They are described as follows:

IDT Standard or FWFT Mode. The two available flag timing modes are

selected using the FWFT/SI input. If FWFT/SI is LOW during master reset then

IDT Standard mode is selected, if it is high then FWFT mode is selected. The

timing modes are described later in Timing Modes: IDT Standard vs First Word

Fall Through (FWFT) Mode section.

Single Data Rate (SDR) or Double Data Rate (DDR). The input/output

data rates are port selectable. This is a versatile feature that allows the user to

select either SDR or DDR on the write ports and/or reads ports of all Queues

using the WDDR and/or RDDR inputs. If WDDR is LOW during master reset

then the write ports of all Queues will function in SDR mode, if it is high then the

write ports will be DDR mode. If RDDR is LOW during master reset then the read

ports of all Queues will function in SDR mode, if it is high then the read port will

be DDR mode. This feature is described in the Signal Descriptions section.

Programmable Almost Empty/Full Flags. The almost empty and almost

full offsets are user programmable, with offset values listed in Table 2. Both PAE

and PAF are double-buffered and updated based on the rising edge of their

respective clocks. PAE with respect to RCLK and PAF with respect to WCLK.

Selectable Bus Width. The bus width can be selected on independently

the read and write ports using the IW and OW inputs. IW pins set the write port

width to x40, x20 or x10 bits wide. The OW pins set the read port to x40, x20

or x10 bits wide.

Programmable Flag Offset Values. These offset values can be user

programmed or they can be set to one of four default values during a master

reset. For default programming, the state of the FSEL[1:0] inputs during master

reset will determine the value. Table 2, Default Programmable offsets lists the

four offset values and how to select them. For programming the offset values to

a specific number, use the serial programming signals (SCLK, SWEN, SREN,

FWFT/SI) to load the value into the offset register. You may also use the JTAG

port on this device to load the offset value. Keep in mind that you must disable

the serial programming signals if you plan to use the JTAG port for loading the

offset values. To disable the serial programming signals, tie SCLK, SWEN,

SREN, and FWFT/SI to VCC. A thorough explanation of the serial and JTAG

programming of the flag offset values is provided in the next section titled “Serial

Write and Reading of Offset Registers”.

I/O Level Selection. The I/Os can be selected for either 2.5V LVTTL levels

or 1.5V HSTL / 1.8V eHSTL levels. The state of the IOSEL input will determine

which I/O level will be selected. If IOSEL is HIGH then the applicable I/Os will

be 1.5V HSTL or 1.8V eHSTL, depending on the voltage level applied to VDDQ

and VREF. For HSTL, VDDQ = 1.5V and VREF = ½ VDDQ. For eHSTL VDDQ

= 1.8V and VREF = ½ VDDQ. If IOSEL is LOW then the applicable I/Os will be

2.5V LVTTL. As noted in the Pin Description section, IOSEL is a CMOS input

and must be tied to either VCC or GND for proper operation.

Input and Output Selection. During master reset, the value of IS[1:0]

and OS[1:0] will be held constant and indicates which internal Queue the read

and write port will select for initial operation. Data will be written to or read from

this internal Queue on the first valid write and read operation after master reset.

IDT72T51248 / IDT72T51258 / IDT72T51268

FSEL1 FSEL0 Offsets n,m

00 7

0163

1 0 127

1 1 1023

TABLE 2 — DEFAULT PROGRAMMABLE

FLAG OFFSETS

NOTES:

1. In default programming, the offset value selected applies to all internal Queues.

2 . To program different offset values for each Queue, serial programming must be used.

TABLE 1 — DEVICE CONFIGURATION

PINS VALUES CONFIGURATION

FWFT/SI 0 IDT Standard

1 FWFT

WDDR 0 Single Data Rate write port

1 Double Data Rate write port

RDDR 0 Single Data Rate read port

1 Double Data Rate read port

IW[1:0] 00 Write port is 10 bits wide

0 1 Write port is 20 bits wide

1 0 Write port is 40 bits wide

11 Restricted

OW[1:0] 0 0 Read port is 10 bits wide

0 1 Read port is 20 bits wide

1 0 Read port is 40 bits wide

11 Restricted

FSEL[1:0] 00 Programmable flag offset registers value = 7

01 Programmable flag offset registers value = 63

10 Programmable flag offset registers value = 127

11 Programmable flag offset registers value = 1023

IOSEL 0 All applicable I/Os (except CMOS) are LVTTL

1 All applicable I/Os (except CMOS) are HSTL/eHSTL

IS[1:0] 00 Queue0

01 Queue1

10 Queue2

11 Queue3

OS[1:0] 00 Queue0

01 Queue1

10 Queue2

11 Queue3

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

SERIAL WRITING AND READING OF OFFSET REGISTERS

These offset registers can be loaded with a default value or they can be user

programmed with another value. One of four default values are detected based

on the state of the FSEL[1:0] inputs, discussed in the Functional Description

section earlier. User programming of the offset values can be performed by

either the dedicated serial programming port or the JTAG port. The dedicated

serial port can be used to load or read the contents of the offset registers. The

offset registers are programmed and read sequentially and behave similar to

a shift register.

The serial read and write operations are performed by the dedicated SCLK,

FWFT/SI, SWEN, SREN, and SDO pins. The total number of bits per device

is listed in Figure 3, Programmable Flag Offset Programming Methods. These

bits account for all four PAE/PAF offset registers in the device. To write to the

offset registers, set the serial write enable signal active (LOW), and on each rising

edge of SCLK one bit from the FWFT/SI pin is serially shifted into the flag offset

four registers, the programming sequence is complete. To read values from the

offsets registers, set the serial read enable active (LOW). Then on each rising

edge of SCLK, one bit is shifted out to the serial data output. The serial read

enable must be kept LOW throughout the entire read operation. To stop reading

the offset register, disable the serial read enable (HIGH). There is serial read

enable to SCLK time for reading the offset registers, as the offset register data

for each Queue is temporarily stored in a scan chain. When data has been

completely read out of the offset registers, any additional read operations to the

offset register will result in zeros as the output data.

Reading and writing of the offset registers can also be accomplished using

the JTAG port. To write to the offset registers using JTAG, set the instructional

load data into each of the offset registers in a similar fashion as the serial

programming described above. To read the values from the offset registers, set

the instructional register to the offset read command (Hex Value = 0x0007). The

TDO of the JTAG port will output data in a similar fashion as the serial

programming described above.

The number of bits required to load the offset registers is dependent on the

size of the device selected. Each offset register requires different total number

of bits depending on input and output bus width configuration. This total must be

programmed into the device in order for all the flags to be programmed correctly.

To change values of one or more offset register, all of the registers must be

reprogrammed serially again.

SCLKTDI*

0008

TCK* SWEN

SREN

No Operation

IW/OW = x40

Serial read from registers:

104 bits for the IDT72T51248

112 bits for the IDT72T51258

120 bits for the IDT72T51268

1 bit for each rising SCLK edge

starting with empty offset (LSB)

ending with full offset (MSB)

IDT72T51248

IDT72T51258

IDT72T51268

Serial write into register:

104 bits for the IDT72T51248

112 bits for the IDT72T51258

120 bits for the IDT72T51268

1 bit for each rising SCLK edge

starting with empty offset (LSB)

ending with full offset (MSB)

6159 drw07

IW/OW = x20

Serial write into register:

112 bits for the IDT72T51248

120 bits for the IDT72T51258

128 bits for the IDT72T51268

1 bit for each rising SCLK edge

starting with empty offset (LSB)

ending with full offset (MSB)

0007

Serial read from registers:

112 bits for the IDT72T51248

120 bits for the IDT72T51258

128 bits for the IDT72T51268

1 bit for each rising SCLK edge

starting with empty offset (LSB)

ending with full offset (MSB)

No Operation

Don’t

care

except

0008 &

0007

IW/OW = x10

Serial write into register:

120 bits for the IDT72T51248

128 bits for the IDT72T51258

136 bits for the IDT72T51268

1 bit for each rising SCLK edge

starting with empty offset (LSB)

ending with full offset (MSB)

Serial read from registers:

120 bits for the IDT72T51248

128 bits for the IDT72T51258

136 bits for the IDT72T51268

1 bit for each rising SCLK edge

starting with empty offset (LSB)

ending with full offset (MSB)

No Operation

NOTES:

* Programming done using the JTAG port.

1. The programming methods apply to both IDT Standard mode and FWFT mode.

2. Parallel programming is not featured in this device.

3. The number of bits includes programming to all four dedicated PAE/PAF offset registers.

Figure 3. Programmable Flag Offset Programming Methods

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

6159 drw08

Offset

PAE3

PAF3

PAE2

PAF2

PAE1

PAF1

PAE0

PAF0

14 - 26

27 - 39

40 - 52

53 - 65

66 - 78

1 - 13

79 - 91

92 - 104

Serial Bits

IDT72T51248

IW/OW = x20

IDT72T51258

IW/OW = x40

IDT72T51248

IW/OW = x20

or IDT72T51258

IW/OW = x20

or IDT72T51268

IW/OW = x40

IDT72T51248

IW/OW = x40

IDT72T51268

IW/OW = x10

IDT72T51258

IW/OW = x10

IDT72T51268

IW/OW = x20

15 - 28

29 - 42

43 - 56

57 - 70

71 - 84

1 - 14

85 - 98

99 - 112

16 - 30

31 - 45

46 - 60

61 - 75

76 - 90

1 - 15

91 - 105

106 - 120

17 - 32

33 - 48

49 - 64

65 - 80

81 - 96

1 - 16

97 - 112

113 - 128

18 - 34

35 - 51

52 - 68

69 - 85

86 - 102

1 - 17

103 - 119

120 - 136

Figure 4. Offset Registers Serial Bit Sequence

TIMING MODES: IDT STANDARD vs FIRST WORD FALL THROUGH

(FWFT) MODE

The IDT72T51248/72T51258/72T51268 support two different timing modes

of operation: IDT Standard mode or First Word Fall Through (FWFT) mode.

The selection of which mode will operate is determined during master reset,

by the state of the FWFT input.

During master reset, if the FWFT pin is LOW, then IDT Standard mode will

be selected. This mode uses the Empty Flag (EF) to indicate whether or not

there are any words present in the Queue. It also uses the Full Flag (FF) to

indicate whether or not the Queue has any free space for writing. In IDT

Standard mode, every word read from the Queue, including the first, must be

requested using the Read Enable (REN) and RCLK.

If the FWFT pin is HIGH during master reset, then FWFT mode will be

selected. This mode uses Output Ready (OR) to indicate whether or not there

is valid data at the data outputs. It also uses Input Ready (IR) to indicate whether

or not the Queue has any free space for writing. In the FWFT mode, the first

word written to an empty Queue goes directly to output bus after three RCLK

rising edges, applying RCS = LOW is not necessary. However, subsequent

words must be accessed using the RCS and RCLK. Various signals, in both

inputs and outputs operate differently depending on which timing mode is in

effect. The timing mode selected affects all internal Queues equally.

IDT STANDARD MODE

In this mode, the status flags FF, PAF, PAE, and EF operate in the manner

outlined in Table 3. To write data into the Queue, Write Enable (WEN) and write

chip select WCS must be LOW. Data presented to the D[39:0] lines will be

clocked into the Queue on subsequent transitions of the Write Clock (WCLK).

After the first write is performed, the Empty Flag (EF) will go HIGH after three

clock cycles. Subsequent writes will continue to fill up the Queue. The

Programmable Almost-Empty flag (PAE) will go HIGH after n + 1 words have

been loaded into the Queue, where n is the empty offset value. The default

setting for these values are listed in Table 3. This parameter is also user

programmable as described in the serial writing and reading of offset registers

section.

Continuing to write data into the Queue without performing read operations

will cause the Programmable Almost-Full flag (PAF) to go LOW. Again, if no

reads are performed, the PAF will go LOW after (8,192-m) writes for the

IDT72T51248, (16,384-m) writes for the IDT72T51258, and (32,768-m)

writes for the IDT72T51268. This is assuming the I/O bus width is configured

to x40. If the I/O is x20, then PAF will go LOW after (16,384-m) writes for the

IDT72T51248, (32,768-m) writes for the IDT72T51258, and (65,536-m)

writes for the IDT72T51268. If the I/O is x10, then PAF will go LOW after

(32,768-m) writes for the IDT72T51248, (65,536-m) writes for the

IDT72T51258, and (131,072-m) writes for the IDT72T51268. The offset “m”

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

6159 drw09

1 to n

(1)

(8,192 - m) to 8,191

8,192

FF PAF PAE EF

HHLL

HHLH

HLHH

LLHH

IDT72T51248 IDT72T51258

IDT72T51258

IDT72T51248

OW = x20

Number of

Words in

Queue

OW = x10

IDT72T51268OW = x40

IDT72T51268

IDT72T51258 IDT72T51268

1 to n

(1)

(16,384 - m) to 16,383

16,384

1 to n

(1)

(32,768 - m) to 32,767

32,768

1 to n

(1)

(65,536 - m) to 65,535

65,536

1 to n

(1)

(131,072 - m) to 131,071

131,072

1 to n+1

(1)

(8,193 - m) to 8,192

8,193

FF PAF PAE EF

HHLL

HHLH

HLHH

LLHH

IDT72T51248 IDT72T51258

IDT72T51258

IDT72T51248

OW = x20

Number of

Words in

Queue

OW = x10

IDT72T51268OW = x40

IDT72T51268

IDT72T51258 IDT72T51268

1 to n+1

(1)

(16,385 - m) to 16,384

16,385

1 to n+1

(1)

(32,769 - m) to 32,768

32,769

1 to n+1

(1)

(65,537 - m) to 65,536

65,537

1 to n+1

(1)

(131,073 - m) to 131,072

131,073

is the full offset value. The default setting for these values are listed in Table 3.

This parameter is also user programmable. See the section on serial writing

and reading of offset registers for details.

When the Queue is full, the Full Flag (FF) will go LOW, inhibiting further write

operations. If no reads are performed after a reset, FF will go LOW after D writes

to the Queue. If the I/O bus width is configured to x40, then D = 8,192 writes

for the IDT72T51248, 16,384 writes for the IDT72T51258, and 32,768 writes

for the IDT72T51268. If the I/O is x20, then D = 16,384 writes for the

IDT72T51248, 32,768 writes for the IDT72T51258, and 65,536 writes for the

IDT72T51268. If the I/O is x10, then D = 32,768 writes for the IDT72T51248,

65,536 writes for the IDT72T51258, and 131,072 writes for the IDT72T51268.

If the Queue is full, the first read operation will cause FF to go HIGH after

two clock cycles. Subsequent read operations will cause PAF to go HIGH at

the conditions described in Table 3. If further read operations occur, without

write operations, PAE will go LOW when there are n words in the Queue, where

n is the empty offset value. Continuing read operations will cause the Queue

to become empty. When the last word has been read from the Queue, the EF

will go LOW inhibiting further read operations. REN is ignored when the Queue

is empty.

When configured in IDT Standard mode, the EF and FF outputs are double

configured in both Single Data Rate and Double Data Rate mode. Relevant

timing diagrams for IDT Standard mode can be found in Figure 12, Write Cycle

and Full Flag Timing (IDT Standard mode).

FIRST WORD FALL THROUGH MODE (FWFT)

In this mode, the status flags OR, IR, PAE, and PAF operate in the manner

outlined in Table 4. To write data into to the Queue, WCS must be LOW. Data

presented to the D[39:0] lines will be clocked into the Queue on subsequent

transitions of WCLK. After the first write is performed, the Output Ready (OR)

flag will go LOW. Subsequent writes will continue to fill up the Queue. PAE will

go HIGH after n + 2 words have been loaded into the Queue, where n is the

empty offset value. The default setting for these values are listed in Table 4.

This parameter is also user programmable as described in the serial writing

and reading of offset registers section.

Continuing to write data into the Queue without performing read operations

will cause the Programmable Almost-Full flag (PAF) to go LOW. Again, if no

reads are performed, the PAF will go LOW after (8,193-m) writes for the

IDT72T51248, (16,385-m) writes for the IDT72T51258, and (32,769-m)

writes for the IDT72T51268. This is assuming the I/O bus width is configured

to x40. If the I/O is x20, then PAF will go LOW after (16,385-m) writes for the

IDT72T51248, (32,769-m) writes for the IDT72T51258, and (65,537-m)

writes for the IDT72T51268. If the I/O is x10, then PAF will go LOW after

(32,769-m) writes for the IDT72T51248, (65,537-m) writes for the

IDT72T51258, and (131,073-m) writes for the IDT72T51268. The offset “m”

is the full offset value. The default setting for these values are listed in Table 4.

This parameter is also user programmable. See the section on serial writing

and reading of offset registers for details.

NOTE:

1. n, m = 7 if FSEL[1:0] = 00, n, m = 63 if FSEL[1:0] = 01, n, m = 127 if FSEL[1:0] = 10, n, m = 1023 if FSEL[1:0] = 11.

NOTE:

1. n, m = 7 if FSEL[1:0] = 00, n, m = 63 if FSEL[1:0] = 01, n, m = 127 if FSEL[1:0] = 10, n, m = 1023 if FSEL[1:0] = 11.

TABLE 3 — STATUS FLAGS FOR IDT STANDARD MODE

TABLE 4 — STATUS FLAGS FOR FWFT MODE

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

When the Queue is full, the Input Ready (IR) will go LOW, inhibiting further

write operations. If no reads are performed after a reset, IR will go LOW after

D writes to the Queue. If the I/O bus width is configured to x40, then D = 8,193

writes for the IDT72T51248, 16,385 writes for the IDT72T51258, and 32,769

writes for the IDT72T51268. If the I/O is x20, then D = 16,385 writes for the

IDT72T51248, 32,769 writes for the IDT72T51258, and 65,537 writes for the

IDT72T51268. If the I/O is x10, then D = 32,769 writes for the IDT72T51248,

65,537 writes for the IDT72T51258, and 131,073 writes for the IDT72T51268.

If the Queue is full, the first read operation will cause IR to go HIGH after two

clock cycles. Subsequent read operations will cause PAF to go HIGH at the

conditions described in Table 4. If further read operations occur, without write

operations, PAE will go LOW when there are n words in the Queue, where

n is the empty offset value. Continuing read operations will cause the Queue

to become empty. Then the last word has been read from the Queue, the OR

will go HIGH inhibiting further read operations. RCS is ignored when the Queue

is empty.

When configured in FWFT mode, the OR flag output is triple register-buffered

and the IR flag output is double register-buffered. Relevant timing diagrams for

FWFT mode can be found in Figure 16, Write Timing in FWFT mode.

HSTL/LVTTL I/O

The inputs and outputs of this device can be configured for either LVTTL

or HSTL/eHSTL operation. If the IOSEL pin is HIGH during master reset, then

all applicable LVTTL or HSTL signals will be configured for HSTL/eHSTL

operating voltage levels. To select between HSTL or eHSTL VREF must be

driven to ½ VREF. Typically a logic HIGH in HSTL would be VREF +300mV

and a logic LOW would be VREF – 300mV. If the IOSEL pin is LOW during master

reset, then all applicable LVTTL or HSTL signals will be configured for LVTTL

operating voltage levels. In this configuration VREF must be set to the static core

voltage of 2.5V. Table 5 illustrates which pins are and are not associated with

this feature. Note that all “Static Pins” must be tied to VCC or GND. These pins

are CMOS only and are purely device configuration pins. Note the IOSEL pin

should be tied HIGH or LOW and cannot toggle before and after master reset.

BUS MATCHING

The write and read port has bus-matching capability such that the input and

output bus can be either 10 bits, 20 bits or 40 bits wide. The bus width of both

the input and output port is determined during master reset using the input and

output width setup pins (IW[1:0], OW[1:0]). The selected port width is applied

to all four Queue ports, such that all four Queues will be configured for either

x10, x20 or x40 bus widths. When writing or reading data from a Queue the

number of memory locations available to be written or read will depend on the

bus width selected and the density of the device.

If the write/read port is 10 bits wide, this provides the user with a Queue depth

of 32,768 x 10 for the IDT72T51248, 65,536 x 10 for the IDT72T51258, or

131,072 x 10 for the IDT72T51268. If the write/read port is 20 bits wide, this

provides the user with a Queue depth of 16,384 x 20 for the IDT72T51248,

32,768 x 20 for the IDT72T51258, or 65,536 x 20 for the IDT72T51268. If

the write/read port is 40 bits wide, this provides the user with a Queue depth

of 8,192 x 40 for the IDT72T51248, 16,384 x 40 for the IDT72T51258, or

32,768 x 40 for the IDT72T51268. The Queue depths will always have a fixed

density of 327,680 bits for the IDT72T51248, 655,360 bits for the IDT72T51258

and 1,310,072 bits for the IDT72T51268 regardless of bus-width configuration

on the write/read port.

When the device is operating in double data rate, the word is twice as large

as in single data rate since one word consists of both the rising and falling edge

of clock. Therefore in DDR, the Queue depths will be half of what it is mentioned

above. For instance, if the write/read port is 10 bits wide, the depth of each

Queue is 16,384 x 10 for the IDT72T51248, 32,768 x 10 for the IDT72T51258,

or 65,536 x 10 for the IDT72T51268.

See Figure 5, Bus-Matching Byte Arrangement for more information.

LVTTL/HSTL/eHSTL STATIC CMOS SIGNALS

Write Port Read Port JTAG Control Pins Serial Port Static Pins

D[39:0] CEF/COR TCK FSEL[1:0] SCLK IOSEL

WCLK EF0/1/2/3 TRST IS[1:0] SREN IW[1:0]

WEN OR0/1/2/3 TMS OS[1:0] SWEN OW[1:0]

FF0/1/2/3 ERCLK TDI PD FWFT/SI RDDR

WCS OE TDO MRS SDO WDDR

CFF/CIR PAE0/1/2/3 PRS

PAF0/1/2/3 Q[39:0] FWFT/SI

RCLK

RCS

REN

EREN

TABLE 5 — I/O VOLTAGE LEVEL CONFIGURATION

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

6159 drw10

x40 INPUT to x10 OUTPUT for Queue0

1st: Read from Queues

D39-D30 D29-D20 D19-D10 D9-D0

1st: Write to Queues

3rd: Read from Queues

2nd: Read from Queues

1st: Read from Queues

LLLH

IS1 IS0 IW1

IW0

4th: Read from Queues

OS1 OS0 OW1 OW0

2nd: Read from Queues

BYTE ORDER ON INPUT PORT:

BYTE ORDER ON OUTPUT PORT:

BCD

Q39-Q30 Q29-Q20 Q19-Q10 Q9-Q0

OS1 OS0 OW1

OW0

BYTE ORDER ON OUTPUT PORT:

x40 INPUT to x20 OUTPUT for Queue0

LLHL

OS1 OS0 OW1 OW0

BYTE ORDER ON OUTPUT PORT:

x40 INPUT to x40 OUTPUT for Queue0

Q39-Q30 Q29-Q20 Q19-Q10 Q9-Q0

ABCD

1st: Read from Queues

Figure 5. Bus-Matching Byte Arrangement

NOTES:

= Outputs are High-Impedanced.

= Inputs set to GND.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

6159 drw11

1st: Read from Queues

LHLL

OS1 OS0 OW1 OW0

2nd: Read from Queues

BYTE ORDER ON OUTPUT PORT:

x20 INPUT to x10 OUTPUT for Queue1

LHHL

OS1 OS0 OW1 OW0

BYTE ORDER ON OUTPUT PORT:

x20 INPUT to x40 OUTPUT for Queue1

Q39-Q30 Q29-Q20 Q19-Q10 Q9-Q0

ABCD

1st: Read from Queues

1st: Write to Queues

LHLH

IS1 IS0 IW1 IW0

2nd: Write to Queues

BYTE ORDER ON INPUT PORT:

D39-D30 D29-D20 D19-D10 D9-D0

LHLH

OS1 OS0 OW1 OW0

BYTE ORDER ON OUTPUT PORT:

x20 INPUT to x20 OUTPUT for Queue1

Q39-Q30 Q29-Q20 Q19-Q10 Q9-Q0

1st: Read from Queues

Q39-Q30 Q29-Q20 Q19-Q10 Q9-Q0

3rd: Read from Queues

4th: Read from Queues

2nd: Read from Queues

Figure 5. Bus-Matching Byte Arrangement (Continued)

NOTES:

= Outputs are High-Impedanced.

= Inputs set to GND.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

6159 drw12

1st: Read from Queues

HLLL

OS1 OS0 OW1 OW0

2nd: Read from Queues

BYTE ORDER ON OUTPUT PORT:

x10 INPUT to x10 OUTPUT for Queue2

HLHL

OS1 OS0 OW1 OW0

BYTE ORDER ON OUTPUT PORT:

x10 INPUT to x40 OUTPUT for Queue2

Q39-Q30 Q29-Q20 Q19-Q10 Q9-Q0

ABCD 1st: Read from Queues

1st: Write to Queues

HLLL

IS1 IS0 IW1 IW0

2nd: Write to Queues

BYTE ORDER ON INPUT PORT:

D39-D30 D29-D20 D19-D10 D9-D0

HLLH

OS1 OS0 OW1 OW0

BYTE ORDER ON OUTPUT PORT:

x10 INPUT to x20 OUTPUT for Queue2

Q39-Q30 Q29-Q20 Q19-Q10 Q9-Q0

AB 1st: Read from Queues

Q39-Q30 Q29-Q20 Q19-Q10 Q9-Q0

3rd: Write to Queues

D4th: Write to Queues

3rd: Read from Queues

4th: Read from Queues

CD 2nd: Read from Queues

Figure 5. Bus-Matching Byte Arrangement (Continued)

NOTES:

= Outputs are in High-Impedanced.

= Inputs are set to GND.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

WRITE PORT OPERATION

The input select pins (IS[1:0]) determine which one of the four Queues the

input bus will write data into. The input select pins are sampled on the rising edge

of every WCLK, and may change on every clock edge. There is no delay

switching from one Queue to another. Note, there is a two-stage pipe-line on

both the read and write data paths causing a two-cycle latency on each

operation. Data can be written on each clock regardless of the queue selected.

A write operation will not be physically written into the queue until the second

clock. Provided data is written every clock, following the first two-cycle latency,

data will reach the respective queue on every clock as well. Data will be written

on the rising (and falling in DDR) edge of write clock provided WEN and WCS

are active on the rising edge of the write clock. Note in double data rate the setup

and hold times of the write enables and write chip selects are sampled with

respect to the rising edge of its respective write clock only. The falling edge of

WCLK does not sample the write enable and write chip select. When selecting

a Queue for write operations the next word can be written to that Queue

immediately on the next clock edge after the new Queue is selected. For

example, if IS[1:0] is set to 01 (Queue1) on WCLK edge 0, then on WCLK edge

1 (next read clock edge) data can be written to Queue1 if WEN and WCS are

enabled.

In FWFT mode the first word written to a selected Queue will automatically

be placed onto the output bus regardless of the state of the corresponding REN,

provided that the selected Queue was empty and its corresponding output ready

flag was inactive. The data will take four clocks to reach the out-put taking into

account the two-cycle write and two-cycle read pipeline. This occurs due to the

nature of the FWFT flag timing. Subsequent writes to the Queue that is not empty

will not fall through to the output bus providing RCS is LOW and RCLK toggles.

In IDT Standard mode, every word, including the first word, must be accessed

by the read enable and read chip select.

READ PORT OPERATION

The output select pins (OS[1:0]) determine which one of the four Queues the

output bus will read data from. The output select pins are sampled on the rising

edge of every RCLK, and may change on every clock edge. Note, there is a

two-stage pipe-line on both the read and write data paths causing a two-cycle

latency on each operation. Data can be read on each clock regardless of the

queue selected. A read operation will not be physically presented to the data

pins until the second clock. Provided data is read every clock, following the first

two-cycle latency, data will reach the data bus on every clock as well. Data will

be read on the rising (and falling in DDR) edge of read clock provided read

enable and read chip select are active (LOW). When selecting a Queue for read

operations the new word read from that Queue will be available immediately on

the next clock edge after the new Queue is selected. For example, if OS[1:0]

is set to 01 (Queue1) on RCLK edge 0, then on RCLK edge 1 (next read clock

edge) data can be read from Queue1 if REN and RCS are enabled. Data is

presented on the second RCLK.

In FWFT mode, the first word written to a selected Queue will automatically

be placed onto the output bus of that respective Queue regardless of the state

of the corresponding read enable, provided that the selected Queue was empty

and its corresponding output ready flag was inactive. The data will take four

clocks to reach the out-put taking into account the two-cycle write and two-cycle

read pipeline. This occurs due to the nature of the FWFT flag timing. Subsequent

writes to the Queue that is not empty will not fall through to the output bus. Note

in FWFT mode, during a Queue selection the next word available in the Queue

will automatically fall through to the output bus regardless of the read enable and

read chip select.

In IDT Standard mode, every word including the first word must be accessed

by the REN and RCS. Unlike FWFT mode, during a Queue selection the next

word available in the Queue will not automatically fall through to the output bus.

The previous word that was read out of the read port will remain on the output

bus if the REN is HIGH an RCS is LOW, if RCS is HIGH the output will be HIGH-Z.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

SIGNAL DESCRIPTIONS

INPUTS:

DATA INPUT BUS (D[39:0])

The data input bus can be 40, 20, or 10 bits wide. D[39:0] are data inputs

for the 40-bit wide data bus, D[19:0] are data inputs for 20-bit wide data bus,

and D[9:0] are data inputs for the 10-bit wide data bus.

MASTER RESET (MRS)

There is a single master reset available for all internal Queues in this device.

A master reset is accomplished whenever the MRS input is taken to a LOW state.

This operation sets the internal read and write pointers of all Queues to the first

location in memory. The programmable almost empty flag will go LOW and the

almost full flags will go HIGH.

If FWFT/SI signal is LOW during master reset then IDT Standard mode is

selected. This mode utilizes the empty and full status flags from the EF/OR and

FF/IR dual-purpose pin. During master reset, all empty flags will be set to LOW

and all full flags will be set to HIGH.

If FWFT/SI signal is HIGH during master reset, then the First Word Fall

Through mode is selected. This mode utilizes the input read and output ready

status flags from the EF/OR and FF/IR dual-purpose pin. During master reset,

all input ready flags will be set to LOW and all output ready flags will be set to

HIGH.

All device configuration pins such as OW[1:0], IW[1:0], IS[1:0], OS[1:0],

WDDR, RDDR, IOSEL, FSEL[1:0] and FWFT/SI needs to be defined before

the master reset cycle. During a master reset the output register is initialized to

all zeros. If the output enable(s) are LOW during master reset, then the output

bus will be LOW. If the output enable(s) are HIGH during master reset, then the

output bus will be in High-impedance. RCS has no affect on the data outputs

during master reset. If the output width OW[1:0] is configured to x10 or x20, then

the unused outputs will be in high-impedance. A master reset is required after

power up before a write operation to any Queue can take place. Master reset

is an asynchronous signal and thus the read and write clocks can be free-

running or idle during master reset. See Figure 10, Master Reset Timing, for

the associated timing diagram.

PARTIAL RESET (PRS0/1/2/3)

A partial reset is a means by which the user can reset both the read and write

pointers of each individual Queue inside the device without changing the

Queue’s configuration. There are four dedicated partial reset signals that each

correspond to an individual Queue. There are restrictions as to when partial

reset can be performed in either operating modes.

During partial reset, the internal read and write pointers are set to the first

location in memory, PAE goes LOW and PAF goes HIGH. Whichever timing

mode was active at the time of Partial Reset will remain active after Partial Reset.

If IDT Standard Mode is active, then FF will go HIGH and EF will go LOW. If

the First Word Fall Through mode is active, then OR will go HIGH and IR will

go LOW.

Following Partial Reset, all values held in the offset registers remain

unchanged. The output registers are initialized to all zeros. All other configura-

tions set up during master reset remain unchanged. PRS is an asynchronous

signal. See Figure 11, Partial Reset Timing, for the associated timing diagram.

FIRST WORD FALL THROUGH/SERIAL IN (FWFT/SI)

This is a dual purpose pin. During Master Reset, the state of the FWFT/SI

input determines whether the device will operate in IDT Standard mode or First

Word Fall Through (FWFT) mode.

If FWFT/SI is LOW before the falling edge of master reset, then IDT Standard

mode will be selected. This mode uses the Empty Flag (EF) to indicate whether

or not there are any words present in the Queues. It also uses the Full Flag

function (FF) to indicate whether or not the Queues has any free space for

writing. In IDT Standard mode, every word read from the Queue, including the

first, must be requested using the Read Enable (REN), Read Chip Select (RCS)

and RCLK.

If FWFT/SI is HIGH before the falling edge of master reset, then FWFT mode

will be selected. This mode uses Output Ready (OR) to indicate whether or not

there is valid data at the data outputs (Qn). It also uses Input Ready (IR) to indicate

whether or not the Queues have any free space for writing. In the FWFT mode,

the first word written to an empty Queue goes directly to output Qn after three

RCLK rising edges, provided that the first RCLK meets tSKEW parameters.

There will be a one RCLK cycle delay if tSKEW is not met. REN and RCS do

not need to be enabled. Subsequent words must be accessed using the REN,

RCS, and RCLK. If RCS is HIGH, the output will be in high-impedance.

The state of the FWFT/SI input must be kept at the present state for the minimum

of the reset recovery time (tRSR) after master reset. After this time, the FWFT/

SI acts as a serial input for loading PAE and PAF offsets into the programmable

offset registers. The serial input is used in conjunction with SCLK, SWEN, SREN,

and SDO to access the offset registers. Serial programming using the FWFT/

SI pin functions the same way in both IDT Standard and FWFT modes.

WRITE CLOCK (WCLK)

The write clock is used to write data to each individual Queue within the device.

A write cycle is initiated on the rising and/or falling edge of the WCLK input. If

the write double data rate (WDDR) mode pin is tied HIGH during master reset,

data will be written on both the rising and falling edge of WCLK, provided that

WEN and WCS are enabled. If WDDR is tied LOW, data will be written only on

the rising edge of WCLK provided that WEN and WCS are enabled.

Data setup and hold times must be met with respect to the LOW-to-HIGH (and

HIGH-to-LOW in DDR) transition of the write clock(s). It is permissible to stop

the write clock(s). Note that while the write clocks are idle, the FF/IR and PAF

flags will not be updated.

WRITE ENABLE (WEN)

The write enable controls whether or not data will be written into the selected

Queue memory. When the write enable input is LOW on the rising edge of WCLK

in single data rate, data is loaded on the rising edge of every WCLK cycle,

provided the device is not full and the write chip select (WCS) is enabled. The

setup and hold times are referenced with respect to the rising edge of WCLK

only. When the write enable input is LOW on the rising edge of WCLK in double

data rate, data is loaded into the selected Queue on the rising and falling edge

of every WCLK cycle, provided the device is not full and the write chip select

(WCS) is enabled. In this mode, the data setup and hold times are referenced

with respect to the rising and falling edge of WCLK. Note that WEN and WCS

are sampled only on the rising edge of WCLK in either data rate mode.

Data is stored in the Queues memory sequentially and independently of any

ongoing read operation. When the write enable and write chip select are HIGH,

no new data is written into the corresponding Queue on each WCLK cycle.

WRITE CHIP SELECT (WCS)

The write chip selects disables the Write Port inputs if it is held HIGH. To

perform normal write operations the write chip select must be enabled, held LOW.

When the write chip select is LOW on the rising edge of WCLK in single data

rate, data is loaded on the rising edge of every WCLK cycle, provided the

device is not full and the write enable (WEN) is LOW. When the WCS is LOW

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

on the rising edge of WCLK, in double data rate, data is loaded into the selected

Queue on the rising and falling edge of every WCLK cycle, provided the device

is not full and the write enable (WEN) is LOW.

When the write chip select is HIGH on the rising edge of WCLK in single data

rate, the write port is disabled and no words are written on the rising edge of

WCLK into the Queue, even if WEN is LOW. If the write chip select is HIGH on

the rising edge of WCLK in double data rate, the write port is also disabled and

no words are written on the rising and falling edge of WCLK into the Queue,

even if WEN is LOW. Note that WCS is sampled on the rising edge of WCLK

only in either data rate mode.

WRITE DOUBLE DATA RATE (WDDR)

When the write double data rate (WDDR) pin is HIGH prior to master reset,

the write port will be set to double data rate mode. In this mode, all write

operations are based on the rising and falling edge of the write clocks, provided

that write enables and write chip selects are LOW for the rising clock edges.

In double data rate the write enable signals are sampled with respect to the rising

edge of write clock only, and a word will be written on both the rising and falling

edge of write clock regardless of whether or not write enable is active on the

falling edge of write clock.

When WDDR is LOW, the write port will be set to single data rate mode. In

this mode, all write operations are based on only the rising edge of the write

clock, provided that WEN and WCS are LOW during the rising edge of write

clock. This pin should be tied HIGH or LOW and cannot toggle before or after

master reset.

READ CLOCK (RCLK)

The read clock is used to read data from each individual Queue within the

device. A read cycle is initiated on the rising and/or falling edge of the RCLK

input. If the read double data rate (RDDR) mode pin is tied HIGH at master reset,

data will be read on both the rising and falling edge of RCLK, provided that REN

and RCS are enabled. If RDDR is tied LOW at master reset, data will be read

only on the rising edge of RCLK provided that REN and RCS are enabled.

There is an associated data access time (tA) for the data to be read out of

the Queues. It is permissible to stop the read clocks. Note that while the read

clocks are idle, the EF/OR and PAE flags will not be updated.

READ ENABLE (REN)

The read enable controls whether or not data will be read out of the memory.

When the read enable input is LOW on the rising edge of RCLK in single data

rate, data will be read on the rising edge of every RCLK cycle, provided the

device is not empty and the read chip select (RCS) is enabled. The associated

data access time (tA) is referenced with respect to the rising edge of RCLK.

When the read enable input is LOW on the rising edge of RCLK in double data

rate, data will be read on the rising and falling edge of every RCLK cycle,

provided the device is not empty and RCS is enabled. In this mode, the data

access times are referenced with respect to the rising and falling edges of RCLK.

Note that REN is sampled only on the rising edge of RCLK in either data rate

mode.

Data is stored in the Queues sequentially and independently of any ongoing

write operation. When the REN and RCS are HIGH, no new data is read on

each RCLK cycle.

To prevent reading from an empty Queue in the IDT Standard mode, the

empty flag of each Queue will go LOW, with respect to RCLK, when the total

number of words in the Queue has been read out, thus inhibiting further read

operations. Upon the completion of a valid write cycle, the empty flag will go

HIGH with respect to RCLK, two cycles later, thus allowing another read to

occur given that tSKEW between WCLK and RCLK is met.

READ CHIP SELECT (RCS)

The read chip select input provides synchronous control of the read port

of the device. When the read chip select is held LOW, the next rising edge of

the corresponding RCLK will enable the output bus. When the read chip select

goes HIGH, the next rising edge of RCLK will send the output bus into high-

impedance and prevent that RCLK from initiating a read, regardless of the state

of REN. During a master or partial Reset the read chip select input has no effect

on the output bus, output enable (OE) is the only input that provides high-

impedance control of the output bus. If output enable is LOW, the data outputs

will be active regardless of read chip select until the first rising edge of RCLK

after a reset is complete. Afterwards if read chip select is HIGH the data outputs

will go to high-impedance.

The read chip select input does not affect the updating of the flags. For

example, when the first word is written to any/all empty Queues, the empty flags

will still go from LOW to HIGH based on a rising edge of the RCLK, regardless

of the state of the read chip select input. Also, when operating the Queue in FWFT

mode the first word written to any/all empty Queues will still be clocked through

to the output bus on the third rising edge of RCLK(s), regardless of the state of

read chip select inputs, assuming that the tSKEW parameter is met. For this reason

the user should pay extra attention to the read chip selects when a data word

is written to any/all empty Queues in FWFT mode. If the read chip select input

is HIGH when an empty Queue is written into, the first word will fall through to

the output register but will not be available on the outputs because the bus is in

high-impedance. The user must enable the read chip selects on the next rising

edge of RCLK to access this first word. See Figure 28, Echo Read Clock and

Read Enable Operation (IDT Standard Mode). See Figure 29, Echo RCLK

and Echo Read Enable Operation (FWFT Mode).

READ DOUBLE DATA RATE (RDDR)

When the read double data rate (RDDR) pin tied HIGH, the read port will be

set to double data rate mode sampled during master reset. In this mode, all read

operations are based on the rising and falling edge of the read clocks, provided

that read enables and read chip selects are LOW. In DDR mode the read enable

signals are sampled with respect to the rising edge of read clock only, and a word

will be read from both the rising and falling edge of read clock regardless of

whether or not read enable and read chip select are active on the falling edge

of read clock.

When RDDR is tied LOW during master reset, the read port will be set to single

data rate mode. In this mode, all read operations are based on only the rising

edge of the RCLK, provided that REN and RCS are LOW during the rising edge

of read clock. This pin should be tied HIGH or LOW and cannot toggle before

and after master reset.

OUTPUT ENABLE (OE)

The output enable controls whether the output bus will be in active or high-

impedance state. When the output enable input is LOW, the output bus becomes

active and drives the data currently in the output register. When the output enable

input (OE) is HIGH, the output bus goes into high-impedance. During master

or partial reset the output enable is the only input that can place the output data

bus into high-impedance. During reset the read chip select input has no effect

on the output data bus.

I/O SELECT (IOSEL)

The inputs and outputs of this device can be configured for either LVTTL or

HSTL/eHSTL operation. If the IOSEL pin is HIGH during master reset, then all

applicable LVTTL or HSTL signals will be configured for HSTL/eHSTL

operating voltage levels. To select between HSTL or eHSTL VREF must be

driven to ½ VDDQ.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

If the IOSEL pin is LOW during master reset, then all applicable LVTTL or

HSTL signals will be configured for LVTTL operating voltage levels. In this

configuration VDDQ should be set to the static core voltage of the 2.5V and VREF

will be ½ VDDQ.

This pin should be tied HIGH or LOW and cannot toggle before or after master

reset. Please refer to Table 5 for a list of applicable LVTTL/HSTL/eHSTL

signals.

POWER DOWN (PD)

This device has a power down feature intended for reducing power

consumption for HSTL/eHSTL configured inputs when the device is idle for a

long period of time. By entering the power down state certain inputs can be

disabled, thereby significantly reducing the power consumption of the part. All

WEN and REN signals must be disabled for a minimum of four WCLK and RCLK

cycles before activating the power down signal. The power down signal is

asynchronous and needs to be held LOW throughout the desired power down

time. During power down, the following conditions for the inputs/outputs signals

are:

•All data in Queue(s) are retained.

•All data inputs become inactive.

•All write and read pointers maintain their last value before power down.

•All enables, chip selects, and clock input pins become inactive.

••

•All data outputs become inactive and enter high-impedance state.

••

•All flag outputs will maintain their current states before power down.

••

•All programmable flag offsets maintain their values.

••

•All Echo clock and enable will become inactive and enter high-

impedance state.

••

•The serial programming and JTAG port will become inactive and enter

high-impedance state.

••

•All setup and configuration CMOS static inputs are not affected, as these

pins are tied to a known value and do not toggle during operation.

All internal counters, registers, and flags will remain unchanged and maintain

their current state prior to power down. Clock inputs can be continuous and free-

running during power down, but will have no affect on the part. However, it is

recommended that the clock inputs be low when the power down is active. To

exit power down state and resume normal operations, disable the power down

signal by bringing it HIGH. There must be a minimum of 1µs waiting period before

read and write operations can resume. The device will continue from where it

had stopped, no form of reset is required after exiting power down state. The

power down feature does not provide any power savings when the inputs are

configured for LVTTL operation. However, it will reduce the current for I/Os that

are not tied directly to VCC or GND. See Figure 35, Power Down Operation,

for the associated timing diagram.

SERIAL CLOCK (SCLK)

The serial clock is used to load data to, and read data from, the programmable

offset registers. Data from the serial input signal (FWFT/SI) can be loaded into

the offset registers on the rising edge of SCLK provided that the serial write

enable (SWEN) signal is LOW. Data can be read from the offset registers via

the serial data output (SDO) signal on the rising edge of SCLK provided that

SREN is LOW. The serial clock can operate at a maximum frequency of 10MHz.

The read operation is non-destructive. The write operation will change registers

on each rising edge of SCLK

SERIAL WRITE ENABLE (SWEN)

The serial write enable input is an enable used for serial programming of the

programmable offset registers. It is used in conjunction with the serial input

(FWFT/SI) and serial clock (SCLK) when programming the offset registers.

When the serial write enable is LOW, data at the serial input is loaded into the

offset register, one bit for each LOW-to-HIGH transition of SCLK. When serial

write enable is HIGH, the offset registers retain the previous settings and no

offsets are loaded. Serial write enable functions the same way in both IDT

Standard and FWFT modes. Each bit that is loaded into the offset register is

serially shifted through the register so each rising edge of SCLK will change the

value of the offsets.

SERIAL READ ENABLE (SREN)

The serial read enable input is an enable used for reading the value of the

programmable offset registers. It is used in conjunction with the serial data output

(SDO) and serial clock (SCLK) when reading the offset registers. When the

serial read enable is LOW, data at the serial data output can be read from the

offset register, one bit for each LOW-to-HIGH transition of SCLK. When serial

read enable is HIGH, the reading of the offset registers will stop. Whenever serial

read enable (SREN) is activated values in the offset registers are read starting

from the first location in the offset registers. On a HIGH to LOW transition, the

SREN copies the values in the offset registers directly into a serial scan out

from the offset register to the serial scan out register will occur. Serial read enable

functions the same way in both IDT Standard and FWFT modes.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

OUTPUTS

DATA OUTPUT BUS (Q[39:0])

The data output bus can be 40, 20, or 10 bits wide. Q[39:0] are data outputs

for the 40-bit wide data bus, Q[19:0] are data outputs for 20-bit wide data bus,

and Q[9:0] are data outputs for the 10-bit wide data bus. In FWFT mode, when

switching from one Queue to another, the data of the newly selected Queue will

always be present on the output bus immediately, two rising RCLK edges after

OS[1:0] is selected regardless of whether or not read enable and read chip

select are active.

EMPTY/OUTPUT READY FLAG (EF/OR0/1/2/3)

There are four empty/output ready flags available in this device, each

corresponding to the individual Queues in memory. This is a dual-purpose pin

that is determined based on the state of the FWFT/SI pin during master reset

for selecting one of the, two timing modes of this device. In the IDT Standard

mode, the empty flags are selected. When an individual Queue is empty, its empty

flag will go LOW, inhibiting further read operations from that Queue. When the

empty flag is HIGH, the individual Queue is not empty and valid read operations

can be applied. See Figure 18, Read Cycle, Empty Flag and First Word Latency

Timing (IDT Standard Mode), for the relevant timing information. Also see Table

3 “Status Flags for IDT Standard Mode” for the truth table of the empty flags.

In FWFT mode, the output ready flags are selected. Output ready flags (OR)

go LOW at the same time that the first word written to an empty Queue appears

on the outputs, which is a minimum of three read clock cycles provided the RCLK

and WCLK meets the tSKEW parameter. OR stays LOW after the RCLK LOW-

to-HIGH transitions that shifts the last word from the Queue to the outputs. OR

goes HIGH when an enabled read operation is performed from an empty queue.

The previous data stays on the outputs, indicating the last word was read.

Further data reads are inhibited until a new word is on the bus when OR goes

LOW again. See Figure 22, Read Timing at Full Boundary (FWFT Mode), for

the relevant timing information. Also see Table 4 “Status Flags for FWFT Mode”

for the truth table of the empty flags.

The empty/output ready flags are synchronous and updated on the rising

edge of RCLK. In IDT Standard mode, the flags are double register-buffered

outputs. In FWFT mode, the flag is triple register-buffered outputs. The four

empty flags operate independent of one another and always indicate the

respective Queue's status.

COMPOSITE EMPTY/OUTPUT READY FLAG (CEF/COR)

This status pin is used to determine the empty state of the current Queue

selected. The composite empty/output ready flag represents the state of the

Queue selected on the read port, such that the user does not have to monitor

each individual Queues’ empty/output ready flags.

The timing of the composite empty/output ready flag differs in IDT Standard

and FWFT modes. In IDT Standard mode, when switching from one Queue to

another, the composite empty flag will update to the status of the newly selected

Queue one RCLK cycle after the rising edge of RCLK that made the new Queue

selection. In FWFT mode, the composite output ready flag will update to the status

of the newly selected Queue on two clock cycles after the rising edge of RCLK

that made the new Queue selection. See Figure 23, Composite Empty Flag (IDT

Standard mode), for the associated timing diagram. See Table 3 and 4 “Status

Flags for IDT Standard and FWFT Mode “ for the truth table of the composite

empty flag.

FULL/INPUT READY FLAG (FF/IR0/1/2/3)

There are four full/input ready flags available in this device, each corresponding

to the individual Queues in memory. This is a dual-purpose pin that is determined

based on the state of the FWFT/SI pin during master reset for selecting the two

timing modes of this device. In the IDT Standard mode, the full flags are selected.

When an individual Queue is full, its full flags will go LOW after the rising edge

of WCLK that wrote the last word, thus inhibiting further write operations to the

Queue. When the full flag is HIGH, the individual Queue is not full and valid write

operations can be applied. See Figure 12, Write Cycle, Full Flag Timing (IDT

Standard Mode), for the associated timing diagram. Also see Table 3 “Status

Flags for IDT Standard Mode” for the truth table of the full flags.

In FWFT mode, the input ready flags are selected. Input ready flags go LOW

when there is adequate memory space in the Queues for writing in data. The

input ready flags go HIGH after the rising edge of WCLK that wrote the last word,

when there are no free spaces available for writing in data. See Figure 16, Write

Timing (FWFT Mode), for the associated timing information. Also see Table 4

“Status Flags for FWFT Mode” for the truth table of the full flags. The input ready

status not only measures the contents of the Queues, but also counts the

presence of a word in the output register. Thus, in FWFT mode, the total number

of writes necessary to make IR HIGH is one greater than needed to set the FF

(LOW) in IDT Standard mode.

FF/IR is synchronous and updated on the rising edge of WCLK. FF/IR are

double register-buffered outputs. The four full flags operate independent of one

another.

To prevent data overflow in the IDT Standard mode, the full flag of each Queue

will go LOW with respect to WCLK, when the maximum number of words has

been written into the Queue, thus inhibiting further write operations. Upon the

completion of a valid read cycle, the full flag will go HIGH with respect to WCLK

two cycles later, thus allowing another write to occur assuming tSKEW has been

met.

To prevent data overflow in the FWFT mode, the input ready flag of each

Queue will go HIGH with respect to WCLK, when the maximum number of words

has been written into the Queue, thus inhibiting further write operations. Upon

the completion of a valid read cycle, the input ready flag will go LOW with respect

to WCLK two cycles later, thus allowing another write to occur assuming tSKEW

has been met.

COMPOSITE FULL/INPUT READY FLAG (CFF/CIR)

This status pin is used to determine the full state of the current Queue selected.

The composite full/input ready flag represents the state of the Queue selected

on the write port, such that the user does not have to monitor each individual

Queues’ full/input ready flag. When switching from one Queue to another, the

composite full/input ready flag will update to the status of the newly selected

Queue one WCLK cycle after the rising edge of WCLK that made the new Queue

selection, regardless of which timing mode the device is operating in. See Figure

25, Composite Full Flag (IDT Standard mode), for the relevant associated

timing diagram. See Table 3 and 4 “Status Flags for IDT Standard and FWFT

Mode “ for the truth table of the composite full flag

PROGRAMMABLE ALMOST EMPTY FLAG (PAE0/1/2/3)

There are four programmable almost empty flags available in this device,

each corresponding to the individual Queues in memory. The programmable

almost empty flag is an additional status flag that notifies the user when the Queue

is near empty. The user may utilize this feature as an early indicator as to when

the Queue will become empty. In IDT Standard mode, PAE will go LOW when

there are n words or less in the Queue. In FWFT mode, the PAE will go LOW

when there are n-1 words or less in the Queue. The offset “n” is the empty offset

value. The default setting for this value is stated in Table 2. Since there are four

internal Queues hence four PAE offset values, n0, n1, n2, and n3.

The four programmable almost empty flags operate independent of one

another.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

PROGRAMMABLE ALMOST FULL FLAG (PAF0/1/2/3)

There are four programmable almost full flags available in this device, each

corresponding to the individual Queues in memory. The programmable almost

full flag is an additional status flag that notifies the user when the Queue is nearly

full. The user may utilize this feature as an early indicator as to when the Queue

will not be able to accept any more data and thus prevent data from being

dropped. In IDT Standard mode, if no reads are performed after master reset,

PAF will go LOW after (D-m) (D meaning the density of the particular device)

words are written to the Queue. In FWFT mode, PAF will go LOW after (D+1-

m) words are written to the Queue. The offset “m” is the full offset value. The default

setting for this value is stated in Table 2. Since there are four internal Queues

hence four PAF offset values, m0, m1, m2, and m3.

The four programmable almost full flags operate independent of one another.

TABLE 6 — TSKEW MEASUREMENT

Data Port Status Flags TSKEW Measurement Datasheet

Configuration Parameter

DDR Input EF/OR Negative Edge WCLK to tSKEW2

t o Positive Edge RCLK

DDR Output FF/IR Negative Edge RCLK to tSKEW2

Positive Edge WCLK

PAE Negative Edge WCLK to tSKEW3

Positive Edge RCLK

PAF Negative Edge RCLK to tSKEW3

Positive Edge WCLK

DDR Input EF/OR Negative Edge WCLK to tSKEW2

t o Positive Edge RCLK

SDR Output FF/IR Positive Edge RCLK to tSKEW1

Positive Edge WCLK

PAE Negative Edge WCLK to tSKEW3

Positive Edge RCLK

PAF Positive Edge RCLK to tSKEW3

Positive Edge WCLK

SDR Input EF/OR Positive Edge WCLK to tSKEW1

t o Positive Edge RCLK

DDR Output FF/IR Negative Edge RCLK to tSKEW2

Positive Edge WCLK

PAE Positive Edge WCLK to tSKEW3

Positive Edge RCLK

PAF Negative Edge RCLK to tSKEW3

Positive Edge WCLK

SDR Input EF/OR Positive Edge WCLK to tSKEW1

t o Positive Edge RCLK

SDR Output FF/IR Positive Edge RCLK to tSKEW1

Positive Edge WCLK

PAE Positive Edge WCLK to tSKEW3

Positive Edge RCLK

PAF Positive Edge RCLK to tSKEW3

Positive Edge WCLK

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

ECHO READ CLOCK (ERCLK)

The echo read clock is a free-running clock output, that will always follow

the RCLK input regardless of the read enables and read chip selects. The

ERCLK output follows the RCLK input with an associated delay. This delay

provides the user with a more effective read clock source when reading data

from the output bus. This is especially helpful at high speeds when variables

within the device may cause changes in the data access times. These variations

in access time may be caused by ambient temperature, supply voltage, or

device characteristics.

Any variations effecting the data access time will also have a corresponding

effect on the echo read clock output produced by the device, therefore the echo

read clock output level transitions should always be at the same position in time

relative to the data outputs. Note, that echo read clock is guaranteed by design

to be slower than the slowest data outputs. Refer to Figure 6, Echo Read Clock

Figure 6. Echo Read Clock and Data Output Relationship

NOTES:

1. REN and RCS are LOW. OE is LOW.

2. tERCLK > tA, guaranteed by design.

3. Qslowest is the data output with the slowest access time, tA. In SDR mode.

4. Time, tD is greater than zero, guaranteed by design.

5. Qslowest is the data output with the slowest access time, tA. In DDR mode.

6159 drw13

ERCLK

SLOWEST

(3)

RCLK

ERCLK

SLOWEST

(5)

and Data Output Relationship, Figure 28, Echo Read Clock and Read Enable

Operation in Double Data Rate Mode and Figure 29, Echo RCLK and Echo

REN

Operation for timing information.

ECHO READ ENABLE (EREN)

The echo read enable output is provided to be used in conjunction with the

echo read clock and provides the device receiving data from the Queue with

a more effective scheme for reading the Queues’ data. The echo read enable

output is controlled by internal logic that becomes active for the read clock cycle

that a new word is read out of the Queue. That is, a rising edge of read clock

will cause echo read enable to go LOW, if both read enable and read chip select

are active and the Queue is not empty. In other words, every cycle samples

the output bus and drives EREN output to the correct value.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

TDO

TDI/

TMS

TCK

TRST

tDOH

Notes to diagram:

t1 =

TCKLOW

t2 =

TCKHIGH

t3 =

tRST

(reset pulse width)

t4 = tRSR (reset recovery)

6159 drw14

tTCK

tDH

tDS tDO

Figure 7. Standard JTAG Timing

Parameter Symbol Test

Conditions Min. Max. Units

JTAG Clock Input Period tTCK - 100 - ns

JTAG Clock HIGH tTCKHIGH -40-ns

JTAG Clock Low tTCKLOW -40-ns

JTAG Reset tRST -50-ns

JTAG Reset Recovery tRSR -50-ns

JTAG

AC ELECTRICAL CHARACTERISTICS

(VCC = 2.5V ± 5%; Tambient (Industrial) = 0°C to +85°C)

NOTE:

1. 50pf loading on external output signals.

SYSTEM INTERFACE PARAMETERS

IDT72T51248

IDT72T51258

IDT72T51268

Parameter Symbol Test Conditions Min. Max. Units

Data Output tDO(1) -20ns

Data Output Hold tDOH(1) 0-ns

Data Input tDS trise=3ns 10 - ns

tDH tfall=3ns 10 -

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

JTAG TIMING SPECIFICATIONS

(IEEE 1149.1 COMPLIANT)

The JTAG test port in this device is fully compliant with the IEEE Standard

Test Access Port (IEEE 1149.1) specifications. Five additional pins (TDI, TDO,

TMS, TCK and TRST) are provided to support the JTAG boundary scan

interface. Note that IDT provides appropriate Boundary Scan Description

Language program files for these devices.

The Standard JTAG interface consists of seven basic elements:

•Test Access Port (TAP)

•TAP controller

•Instruction Register (IR)

•Data Register Port (DR)

•Bypass Register (BYR)

•ID Code Register

•Flag Programming

The following sections provide a brief description of each element. For a

complete description refer to the IEEE Standard Test Access Port Specification

(IEEE Std. 1149.1-1990).

The Figure below shows the standard Boundary-Scan Architecture

Figure 8. JTAG Architecture

TEST ACCESS PORT (TAP)

The TAP interface is a general-purpose port that provides access to the

internal JTAG state machine. It consists of four input ports (TCLK, TMS, TDI,

TRST) and one output port (TDO).

THE TAP CONTROLLER

The TAP controller is a synchronous finite state machine that responds to

TMS and TCLK signals to generate clock and control signals to the Instruction

and Data Registers for capture and updating of data passed through the TDI

serial input.

In Pad

Incell

Core

Logic

Outcell

Out Pad

All outputs

All inputs

Eg: Dins, Clks

(BSDL file

describes the

chain order)

Bypass

Instruction

TA P

TMS

TDI

TCK

TRST

Instruction

Select

Enable

TDO

6159 drw15

Flag Offset Chain

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

Refer to the IEEE Standard Test Access Port Specification (IEEE Std.

1149.1) for the full state diagram

All state transitions within the TAP controller occur at the rising edge of the

TCLK pulse. The TMS signal level (0 or 1) determines the state progression

that occurs on each TCLK rising edge. The TAP controller takes precedence

over the Queue operation and must be reset after power up of the device. See

TRST description for more details on TAP controller reset.

Test-Logic-Reset All test logic is disabled in this controller state enabling the

normal operation of the IC. The TAP controller state machine is designed in such

a way that, no matter what the initial state of the controller is, the Test-Logic-Reset

state can be entered by holding TMS at high and pulsing TCK five times. This

is the reason why the Test Reset (TRST) pin is optional.

Run-Test-Idle In this controller state, the test logic in the IC is active only if

certain instructions are present. For example, if an instruction activates the self

test, then it will be executed when the controller enters this state. The test logic

in the IC is idle otherwise.

Select-DR-Scan This is a controller state where the decision to enter the

Data Path or the Select-IR-Scan state is made.

Select-IR-Scan This is a controller state where the decision to enter the

Instruction Path is made. The Controller can return to the Test-Logic-Reset state

other wise.

Figure 9. TAP Controller State Diagram

Capture-IR In this controller state, the shift register bank in the Instruction

last two significant bits are always required to be “01”.

Shift-IR In this controller state, the instruction register gets connected

between TDI and TDO, and the captured pattern gets shifted on each rising edge

of TCK. The instruction available on the TDI pin is also shifted in to the instruction

Exit1-IR This is a controller state where a decision to enter either the Pause-

IR state or Update-IR state is made.

Pause-IR This state is provided in order to allow the shifting of instruction

Exit2-DR This is a controller state where a decision to enter either the Shift-

IR state or Update-IR state is made.

Update-IR In this controller state, the instruction in the instruction register scan

chain is latched in to the register of the Instruction Register on every falling edge

of TCK. This instruction also becomes the current instruction once it is latched.

Capture-DR In this controller state, the data is parallel loaded in to the data

registers selected by the current instruction on the rising edge of TCK.

Shift-DR, Exit1-DR, Pause-DR, Exit2-DR and Update-DR These

controller states are similar to the Shift-IR, Exit1-IR, Pause-IR, Exit2-IR and

Update-IR states in the Instruction path.

Test-Logic

Reset

Run-Test/

Idle

Select-

DR-Scan

Select-

IR-Scan

111

Capture-IR

Capture-DR

Exit1-DR

Pause-DR

Exit2-DR

Update-DR

Exit1-IR

Exit2-IR

Update-IR

6159 drw16

Shift-DR

Shift-IR

Pause-IR

Input is

TMS

NOTES:

1. Five consecutive TCK cycles with TMS = 1 will reset the TAP.

2. TAP controller automatically resets upon power-up.

3. TAP controller must be reset before normal Queue operations can begin.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

THE INSTRUCTION REGISTER

The instruction register (IR) is eight bits long and tells the device what

instruction is to be executed. Information contained in the instruction includes the

mode of operation (either normal mode, in which the device performs its normal

logic function, or test mode, in which the normal logic function is inhibited or

altered), the test operation to be performed, which of the four data registers is

to be selected for inclusion in the scan path during data-register scans, and the

source of data to be captured into the selected data register during Capture-DR.

TEST DATA REGISTER

The Test Data register contains three test data registers: the Bypass, the

Boundary Scan register and Device ID register.

These registers are connected in parallel between a common serial input

and a common serial data output.

The following sections provide a brief description of each element. For a

complete description, refer to the IEEE Standard Test Access Port Specification

(IEEE Std. 1149.1-1990).

TEST BYPASS REGISTER

The register is used to allow test data to flow through the device from TDI

to TDO. It contains a single stage shift register for a minimum length in the serial

path. When the bypass register is selected by an instruction, the shift register

stage is set to a logic zero on the rising edge of TCLK when the TAP controller

is in the Capture-DR state.

The operation of the bypass register should not have any effect on the

operation of the device in response to the BYPASS instruction.

THE BOUNDARY-SCAN REGISTER

The boundary-scan register (BSR) is 48 bits long. It contains one

boundary-scan cell (BSC) for each normal-function input pin and one BSC for

each normal-function I/O pin (one single cell for both input data and output data).

The BSR is used 1) to store test data that is to be applied externally to the device

output pins, and/or 2) to capture data that appears internally at the outputs of

the normal on-chip logic and/or externally at the device input pins.

THE DEVICE IDENTIFICATION REGISTER

The Device Identification Register is a Read Only 32-bit register used to

specify the manufacturer, part number and version of the device to be

determined through the TAP in response to the IDCODE instruction.

IDT JEDEC ID number is 0xB3. This translates to 0x33 when the parity is

dropped in the 11-bit Manufacturer ID field.

For the IDT72T51248/72T51258/72T51268, the Part Number field con-

tains the following values:

IDT72T51248/258/268 JTAG Device Identification Register

31(MSB) 28 27 12 11 1 0(LSB)

V ersion (4 bits) Part Number (16-bit) Manufacturer ID (1 1-bit)

0000 0033 (hex) 1

JTAG INSTRUCTION REGISTER

The Instruction register allows an instruction to be serially input into the

device when the TAP controller is in the Shift-IR state. The instruction is decoded

to perform the following:

•Select test data registers that may operate while the instruction is

current. The other test data registers should not interfere with chip

operation and the selected data register.

•Define the serial test data register path that is used to shift data between

TDI and TDO during data register scanning.

The Instruction Register is a 4 bit field (i.e. IR3, IR2, IR1, IR0) to decode

16 different possible instructions. Instructions are decoded as follows.

Hex Instruction Function

Value

0000 EXTEST Test external pins

0001 SAMPLE/PRELOAD Select boundary scan register

0002 IDCODE Selects chip identification register

0003 CLAMP Fix the output chains to scan chain values

0004 HIGH-IMPEDANCE Puts all outputs in high-impedance state

0007 OFFSET READ Read PAE/PAF offset register values

0008 OFFSET WRITE Write PAE/PAF offset register values

000F BYPASS Select bypass register

Private Several combinations are private (for IDT

internal use). Do not use codes other than

those identified above.

JTAG Instruction Register Decoding

The following sections provide a brief description of each instruction. For

a complete description refer to the IEEE Standard Test Access Port Specification

(IEEE Std. 1149.1-1990).

EXTEST

The required EXTEST instruction places the device into an external

boundary-test mode and selects the boundary-scan register to be connected

between TDI and TDO. During this instruction, the boundary-scan register is

accessed to drive test data off-chip via the boundary outputs and receive test

data off-chip via the boundary inputs. As such, the EXTEST instruction is the

workhorse of IEEE. Std 1149.1, providing for probe-less testing of solder-joint

opens/shorts and of logic cluster function.

SAMPLE/PRELOAD

The required SAMPLE/PRELOAD instruction allows the device to remain in

a normal functional mode and selects the boundary-scan register to be

connected between TDI and TDO. During this instruction, the boundary-scan

functional data entering and leaving the device. This instruction is also used to

preload test data into the boundary-scan register before loading an EXTEST

instruction.

IDCODE

The optional IDCODE instruction allows the device to remain in its functional

mode and selects the optional device identification register to be connected

between TDI and TDO. The device identification register is a 32-bit shift register

containing information regarding the device manufacturer, device type, and

version code. Accessing the device identification register does not interfere with

the operation of the device. Also, access to the device identification register

should be immediately available, via a TAP data-scan operation, after power-

up of the device or after the TAP has been reset using the optional TRST pin

or by otherwise moving to the Test-Logic-Reset state.

Device Part# Field

IDT72T51248 04C1 (hex)

IDT72T51258 04C2 (hex)

IDT72T51268 04C3 (hex)

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

CLAMP

The optional CLAMP instruction sets the outputs of an device to logic levels

determined by the contents of the boundary-scan register and selects the one-

bit bypass register to be connected between TDI and TDO. Before loading this

instruction, the contents of the boundary-scan register can be preset with the

SAMPLE/PRELOAD instruction. During this instruction, data can be shifted

through the bypass register from TDI to TDO without affecting the condition of

the outputs.

HIGH-IMPEDANCE

The optional High-Impedance instruction sets all outputs (including two-state

as well as three-state types) of an device to a disabled (high-impedance) state

and selects the one-bit bypass register to be connected between TDI and TDO.

During this instruction, data can be shifted through the bypass register from TDI

to TDO without affecting the condition of the device outputs.

OFFSET READ

This instruction is an alternative to serial reading the offset registers for the

PAE/PAF flags. When reading the offset registers through this instruction, the

dedicated serial programming signals must be disabled.

OFFSET WRITE

This instruction is an alternative to serial programming the offset registers for

the PAE/PAF flags. When writing the offset registers through this instruction, the

dedicated serial programming signals must be disabled.

BYPASS

The required BYPASS instruction allows the device to remain in a normal

functional mode and selects the one-bit bypass register to be connected

between TDI and TDO. The BYPASS instruction allows serial data to be

transferred through the IC from TDI to TDO without affecting the operation of

the device.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

EF/OR(8)

0/1/2/3

RSF

If FWFT = HIGH, OR = HIGH

If FWFT = LOW, EF = LOW

RSF

PAF(8)

0/1/2/3

RSF

Q[39:0]

RSF

OE = HIGH

OE = LOW

6159 drw17

OW[1:0](4),

IW[1:0](4)

FSEL[1:0](4)

PFM(4)

HIGH = Synchronous PAE/PAF Timing

LOW = Asynchronous PAE/PAF Timing

HIGH = FWFT Mode

LOW = IDT Standard Mode

RDDR(4),

WDDR(4)

FWFT/SI(4)

IOSEL(4)

HIGH = Read/Write Double Data Rate

LOW = Read/Write Single Data Rate

HIGH = HSTL I/Os

LOW = LVTTL I/Os

RSS

If FWFT = LOW, FF = HIGH

If FWFT = HIGH, IR = LOW

FF/IR(8)

0/1/2/3

PAE(8)

0/1/2/3

IS[1:0](4),

OS[1:0](4)

RSS

MRS

WEN

REN(7)

RSS

SWEN,

SREN

RSS

RSR

Figure 10. Master Reset Timing

NOTES:

1. OE can toggle during master reset. During master reset, the high-impedance control of the Qn data outputs is provided by OE only.

2. PRS should be HIGH during a MRS.

3. RCLK, WCLK and SCLK can be free running or idle.

4. The state of these pins are latched when the master reset pulse is LOW.

5. JTAG clock should not toggle during master reset.

6. RCS and WCS can be HIGH or LOW until the first rising edge of RCLK after master reset is complete.

7. EREN wave form is identical to REN, ERCLK wave form is identical to RCLK.

8. Composite flag wave form is identical to EF, FF, PAE, PAF wave form above.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

WEN,

REN

RSS

PRS2/3

(1)

RSS

RSR

RCLK

123

PRS0/1

(1,3)

6159 drw18

FF/IR0/1

RSF

Current State

FF/IR2/3

RSF If FWFT = HIGH, FF = HIGH

If FWFT = LOW, IR = LOW

If FWFT = HIGH, CFF = HIGH

If FWFT = LOW, CIR = LOW

PAE0/1

RSF

Current State

PAE2/3

RSF

PAF0/1

RSF

Current State

PAF2/3

RSF

Q[39-0]

(2,4)

RSF OE = HIGH

OE = LOW

Current State

OS[1:0],

IS[1:0]

ENS

00 = Queue 0 01 = Queue 1

EF/OR0/1

RSF

Current State

EF/OR2/3

RSF If FWFT = HIGH, OR = HIGH

If FWFT = LOW, EF = LOW

If FWFT = HIGH, OR = HIGH

If FWFT = LOW, EF = LOW

CEF/COR

RSF

Current State

If FWFT = HIGH, COR = HIGH

If FWFT = LOW, CEF = LOW

Output Data Queue 0 Output Data Queue 1

Figure 11. Partial Reset Timing

NOTES:

1. During the input and/or output selection of two Queues, partial reset of the two Queues involved are prohibited.

2. During partial reset the high-impedance control of the output is provided by OE only.

3. PRS0/1 must go LOW after the fourth rising edge of RCLK/WCLK from where IS[1:0] and/or OS[1:0] transitioned.

4. This is the output data from Queue0 and Queue1.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

Figure 12. Write Cycle and Full Flag Timing (IDT Standard mode, SDR to SDR, x40 In to x40 Out)

WEN

D[39:0]

D-1

WCLK

No Write

FF0

WFF

OS[1:0]

00=Queue 0

6157 drw19

RCLK

REN

01=Queue 1

Q[39:0]

(4)

Previous Word Queue 0

Word 0 Queue 2

Word 1 Queue 2

ENH

WFF

ENS

SKEW1(3)

ENS

ENH

10=Queue 2

Word 2 Queue 2

Q0 Q0 Q0 Q1 Q2 Q3 Q4

Previous Word + 1 Queue 0 Word 0 Queue 1

NOTES:

1. WCS = LOW, OE = LOW, WDDR = LOW, RDDR = LOW, and IS[1:0] = 00.

2. WCLK must be free running for FF0 to update.

3. tSKEW1, is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that FF0 will go HIGH (after one WCLK cycle plus tWFF). If the time between the rising edge of RCLK and the rising edge of WCLK

is less than tSKEW1, then the FF0 deassertion may be delayed one extra WCLK cycle. (See Table 6 - TSKEW measurement).

4. Two stage pipeline causes a two-cycle latency on wrtie operations.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

Figure 13. Write Cycle and Full Flag Timing in DDR mode ( IDT Standard mode, DDR to DDR, x40 In to x40 Out)

NOTES:

1. tSKEW2 is the minimum time between a falling RCLK edge and a rising WCLK edge to guarantee that FF0 will go HIGH (after one WCLK cycle plus tWFF). If the time between the falling edge of the RCLK and the rising edge of WCLK

is less than tSKEW2, then FF0 deassertion may be delayed one extra WCLK cycle. (See Table 6 - TSKEW measurement).

2. OE0 = LOW, WCS = LOW, RCS = LOW, WDDR = HIGH, RDDR = HIGH, IS[1:0] = 00, and OS[1:0] = 00.

3. WCLK must be free running for FF0 to update.

Word 1

Q[39:0]

6159 drw20

NO WRITE

D[39:0]

RCLK

WCLK

WEN

FF0

CLKL

CLKH

CLK

SKEW2

(1)

SKEW2

(1)

REN

NO WRITE

WD+1

WD+2 WD+3

WFF

ENH

ENS

ENH

ENS

Data in Output Register Word 2 Word 3

Word 4

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

Figure 14. Write Cycle and Full Flag Timing with bus-matching and rate matching (IDT Standard mode, DDR to SDR, x10 In to x20 Out)

WCLK

FF0

WEN

RCS

ENS

SKEW1(1)

Q[39:0]

RCLK

ENH

ENS

WFF

D[39:0]

REN

RCSLZ

WFF

SKEW1(1)

ENS

ENH

WFF

CLK

CLKH

CLKL

NO WRITE

WFF

+ 1

Wx Wx+1 Wx+2 Wx+3

6159 drw21

NOTES:

1. tSKEW1 is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that FF0 will go HIGH (after one WCLK cycle plus tWFF). If the time between the rising edge of the RCLK and the rising edge of the

WCLK is less than tSKEW1, then the FF0 deassertion may be delayed one extra WCLK cycle. (See Table 6 - TSKEW measurement).

2. OE0 = LOW, WCS = LOW, WDDR = HIGH, RDDR = LOW, IS[1:0] = 00, and OS[1:0] = 00.

3. WCLK must be free running for FF0 to update.

4. WX is a 10 bit word. D[39:10] are not used and should be corrected to GND.

5. WY is a 20 bit word. Q[39:20] are not used and should be left open.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

Figure 15. Write Cycle and Full Flag Timing with rate matching (IDT Standard mode, SDR to DDR, x40 In to x40 Out)

WCLK

FF0

WEN

RCS

ENS

Q[39:0]

RCLK

ENH

ENS

WFF

D[39:0]

REN

RCSLZ

ENS

ENH

CLK

NO WRITE

WFF

Word 1 Word 3

+2 W

CLKH

WFF

SKEW2(1)

WFF

ENS

RCSHZ

Word 0 Word 2

6159 drw22

SKEW2(1)

NOTES:

is less than tSKEW2, then FF0 deassertion may be delayed one extra WCLK cycle. (See Table 6 - TSKEW measurement).

2. OE0 = LOW, WCS = LOW, RCS = LOW, WDDR = LOW, RDDR = HIGH, IS[1:0] = 00, and OS[1:0] = 00.

3. WCLK must be free running for FF0 to update.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

RCLK

SKEW1

Word 0

Q[39:0]

6159 drw23

Previous Data in Output Register

Word 1

Word 2 Word 3

REN

ENS

OR0t

REF

D[39:0]

WEN

WCLK

ENS

Word 1

Word 0

ENH

Word 2 Word 3

12 3

REF

Figure 16. Write Timing in FWFT mode (FWFT mode, SDR to SDR, x40 In to x40 Out)

NOTES:

1. tSKEW, is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that FF0 will go HIGH (after one WCLK cycle plus tWFF). If the time between the rising edge of RCLK and the rising edge of WCLK

is less than tSKEW1, then the FF0 deassertion may be delayed one extra WCLK cycle. (See Table 6 - TSKEW measurement).

2. WCS = LOW, OE = LOW, WDDR = LOW, RDDR = LOW, IS[1:0] = 00, OS[1:0] = 0, and RCS = LOW.

3. WCLK must be free running for FF0 to update.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

Figure 17. Write Cycle and First Word Latency Timing in DDR mode (FWFT mode, DDR to DDR, x40 In to x40 Out)

NOTES:

1. tSKEW2 is the minimum time between a falling WCLK edge and a rising RCLK edge to guarantee that OR0 will go LOW after two RCLK cycle plus tREF. If the time between the falling edge of WCLK and the rising edge of RCLK

is less than tSKEW2, then OR0 assertion may be delayed one extra RCLK cycle. (See Table 6 - TSKEW measurement).

2. OE = LOW, RCS = LOW, WCS = LOW, WDDR = HIGH, RDDR = HIGH, IS[1:0] = 00, and OS[1:0] = 00.

3. First data word latency = tSKEW2 + RCLK full period + tREF.

4. RCLK must be free running for OR0 to update.

WCLK

WEN

OR0

SKEW2(1)

Q[39:0]

RCLK

D[39:0]

REN

Previous Data In Output Register

6159 drw24

Word 1 Word 2

ENH

12 3

Word 3 Word 4

ENH

ENS

REF

ENH

ENS

Word 1 Word 2

Word 3 Word 4

SKEW2

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

RCLK

REN

EF0

tREF tREF tREF

WEN

D[39:0]

Q[39:0]

No Read No Read

D+1

WCLK

tENH

tDH

D+1

6159 drw25

tDS

tENS

tSKEW

tENH tENS

D-1

D-2

Figure 18. Read Cycle, Empty Flag and First Word Latency (IDT Standard mode, SDR to SDR, x40 In to x40 Out)

NOTES:

1. OE = LOW, RCS = LOW, WCS = LOW, WDDR = LOW, RDDR = LOW, IS[1:0] = 00, and OS[1:0] = 00.

2. First data word latency = tSKEW1 + RCLK full period + tREF.

3. RCLK must be free running for EF0 to update.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

EF0

Q[39:0]

WCLK

WEN

D[39:0]

Word 0

REN

RCLK

SKEW2

REF

6159 drw26

Word 0

ENS

Word 1 Word 2 Word 3

REF

Word 1

Word 2

Word 3

Figure 19. Read Cycle, Empty Flag and First Word Latency in DDR mode (IDT Standard mode, DDR to DDR, x40 In to x40 Out)

NOTES:

1. tSKEW2 is the minimum time between a falling RCLK edge and a rising WCLK edge to guarantee that FF0 will go HIGH (after one WCLK cycle plus tWFF). If the time between the

falling edge of the RCLK and the rising edge of WCLK is less than tSKEW2, then FF0 deassertion may be delayed one extra WCLK cycle. (See Table 6 - TSKEW measurement).

2. OE0 = LOW, WCS = LOW, RCS = LOW, WDDR = HIGH, RDDR = HIGH, IS[1:0] = 00, and OS[1:0] = 00.

3. First data word latency = tSKEW2 + RCLK full period + tREF.

4. RCLK must be free running for EF0 to update.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

Q[39:0]

(5)

WCLK

WEN

D[39:0]

6159 drw27

Word 0

ENH

ENS

EF0

REF

REN

RCLK

SKEW2

Previous Data in Output Register

Word 0 (LSB)

ENS

REF

NO READ

Word 0 (MSB) Word 1 (LSB) Word 1 (MSB)

Word 1

Figure 20. Read Cycle, Empty Flag and First Word Latency with bus-matching and rate-matching (IDT Standard mode, DDR to SDR, x40 In to x20 Out)

NOTES:

is less than tSKEW2, then FF0 deassertion may be delayed one extra WCLK cycle. (See Table 6 - TSKEW measurement).

2. OE = LOW, WCS = LOW, RCS = LOW, WDDR = HIGH, RDDR = HIGH, IW = 10, OW = 01, IS[1:0] = 00, and OS[1:0] = 00.

3. First data word latency = tSKEW2 + RCLK full period + tREF.

4. RCLK must be free running for EF0 to update.

5. Word X LSB = D[19:0], Word X MSB = D[39:20], Q[39:20] will be high-impedanced.

6. Q[39:20] are not used and must be left open.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

Figure 21. Read Cycle and Empty Flag Timing with bus-matching and rate-matching (IDT Standard mode, SDR to DDR, x10 In to x20 Out)

NOTES:

1. tSKEW1 is the minimum time between a rising WCLK edge and a rising RCLK edge to guarantee that EF0 will go HIGH (after one RCLK cycle plus tREF). If the time between the rising edge of WCLK and the rising edge of

RCLK is less than tSKEW1, then EF0 deassertion may be delayed one extra RCLK cycle. (See Table 6 - TSKEW measurement).

2. OE0 = LOW, RCS = LOW, WCS = LOW, WDDR = LOW, RDDR = HIGH, IW = 00, and OW = 01.

3. First data word latency = tSKEW1 + RCLK full period + tREF.

4. RCLK must be free running for EF0 to update.

5. Word WX LSB = D[9:0], Word WX MSB = D[19:10].

6. D[39:10] are not used and should be tied to GND. Q[39:20] are not used and must be left open.

Q[39:0]

SKEW1

(1)

WCLK

RCLK

REN

WEN

REF

EF0

D[39:0]

6159 drw28

REF

Last Word

(LSB)

Last 20-bit Word (MSB)

ENS

ENH

0 (LSB)

0 (MSB)

1 (LSB)

tENH

tENS

(MSB,LSB)

CLK

CLKH

CLKL

Previous Data

ENH

NO Read

1 (MSB)

(MSB,LSB)

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

6159 drw29

Word 0

ENS

RCLK

Q[39:0]

REN

IR0

WFF

SKEW1

D[39:0]

WEN

WCLK

Word

D+1

ENH

ENS

Word 1 Word 2 Word 3

Figure 22. Read Timing at Full Boundary (FWFT mode, SDR to SDR, x40 In to x40 Out)

NOTES:

1. tSKEW1, is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that IR0 will go HIGH (after one WCLK cycle plus tWFF). If the time between the

rising edge of RCLK and the rising edge of WCLK is less than tSKEW1, then the IR0 deassertion may be delayed one extra WCLK cycle. (See Table 6 - tSKEW measurement).

2 . WCLK must be free running for IR0 to update.

3. OE = LOW, RCS = LOW, WCS = LOW, WDDR = LOW, RDDR = LOW, IW = 10, and OW = 10.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

REN

EF1

RCLK

6159 drw30

12 3

Q[39:0]

Word

D-1

Queue 1

OS[1:0]

01 = Queue 1

Word D Queue 1

ENS

Word A Queue 3

REF

CEF

REF

No Read

11 = Queue 3

Queue 1 Status Queue 3 Status

Figure 23. Composite Empty Flag (IDT Standard mode, SDR to SDR, x40 In to x40 Out)

NOTES:

1. RCS = LOW, and OE = LOW.

2. EF3 is HIGH.

3. Word D-1 is the second to last word in Queue 1. Word D is the last word in Queue 1.

4. Word A is the next available word in Queue 3.

5. The composite empty flag will update to the newly selected Queue after one RCLK cycle once a new Queue has been selected using OS[1:0].

REN

OR1

RCLK

6159 drw31

12 3

Q[39:0]

Word

D-1

Queue 1

OS[1:0]

01 = Queue 1 11 = Queue 3

Word D Queue 1

ENS

Word A Queue 3

REF

COR

REF

Queue 1 Status Queue 3 Status

Figure 24. Composite Output Ready Flag (FWFT mode, SDR to SDR, x40 In to x40 Out)

NOTES:

1. RCS = LOW, and OE = LOW.

2. OR3 is LOW.

3. Word D-1 is the second to last word in Queue 1. Word D is the last word in Queue 1.

4. Word A is the next available word in Queue 3.

5. The composite output ready flag will update to the newly selected Queue after two RCLK cycles once a new Queue has been selected using OS[1:0].

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

WEN

WCLK

6159 drw32

CFF

tWFF

12 3

IS[1:0]

01 = Queue 1

tENS

No Write

D[39:0]

Word D Queue 1

tDS tDH

tDH

Word A Queue 3 Word A+1 Queue 3

FF1

tWFF

tDS tDH tDS

11 = Queue 3

Queue 1 Status Queue 3 Status

Figure 25. Composite Full Flag (IDT Standard mode, SDR to SDR, x40 In to x40 Out)

NOTES:

1. WCS = LOW.

2. FF3 is HIGH.

3. Word D is the last word written that causes Queue 1 to be full.

4. Word A is the next word written to Queue 3.

5. The composite full flag will update to the newly selected Queue after one WCLK cycle once a new Queue has been selected using IS[1:0].

WEN

WCLK

6159 drw33

CIR

WFF

12 3

IS[1:0]

ENS

No Write

D[39:0]

IR1

WFF

Word D+1 Queue 1

Word A Queue 3 Word A+1 Queue 3

01 = Queue 1

11 = Queue 3

WFF

Queue 1 Status Queue 3 Status

Figure 26. Composite Input Ready Flag (FWFT mode, SDR to SDR, x40 In to x40 Out)

NOTES:

1. WCS = LOW.

2. IR3 = LOW.

3 . Word D+1 is the last word written that causes Queue 1 to be full. Word D fell through to the output.

4. Word A is the next word written to Queue 3.

5. The composite full flag will update to the newly selected Queue after one WCLK cycle once a new Queue has been selected using IS[1:0].

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

Figure 27. Queue Switch at Every Clock Cycle (IDT Standard mode, SDR to SDR, x40 In to x40 Out)

NOTES:

1. The reading and writing to different Queues can occur at every clock cycle. There is a two cycle latency pipeline when switching from one Queue to another.

2. Word group A is written into Queue 0. Word group B Queue 1. Word group C Queue 2. Word group D Queue 3.

3. The composite empty and full flags will update the status of the newly selected Queue one cycle clock after the Queue has been selected.

4. OE = LOW, WDDR = HIGH, and RDDR = HIGH.

5 . If FWFT mode is selected, the composite input ready flag (CIR) timing is the same as CEF. The composite output ready (COR) will update after two clock cycles instead of one.

IS[1:0]

WCLK

WEN

ENS

00 = Queue 0 01 = Queue 1 10 = Queue 2

11 00

D[39:0]

Word X Queue X Word X Queue X

CFF

Queue X STATUS

ENS

00 = Queue 0 01 = Queue 1 10 = Queue 2 11 = Queue 3

01 10

Queue X STATUS Queue 0 STATUS Queue 1 STATUS Queue 2 STATUS Queue 3 STATUS

OS[1:0]

RCLK

REN

Q[39:0]

CEF

Queue 0

tENH

tDH

tENS

tENH

Queue 0 STATUS Queue 0 STATUS Queue 1 STATUS Queue 2 STATUS

01 10 11

00 01 10

Queue 3 STATUS Queue 1 STATUS Queue 2 STATUS Queue 0 STATUS

Queue 2 STATUS Queue 3 STATUS Queue 0 STATUS Queue 1 STATUS

tENS

Word A Queue 0 Word A+1 Queue 0 Word B Queue 1 Word C Queue 2 Word C+1 Queue 2 Word D Queue 3 Word A+2 Queue 0

Word B+1 Queue 1

Word X Queue X Word E Queue 0 Word F Queue 1 Word G Queue 2 Word H Queue 3 WordH+1 Queue 3 Word F+1 Queue 1 Word G+1 Queue 2

123

Word X+1 Queue X

6159 drw34

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

6159 drw35

RCLK

REN

ERCLK

RCS

ENS

EREN

CLKEN

EF0

REF

Q[39:0]

OLZ

WD-1 WD Last WordWD-2WD-3WD-4

ENS

CLKEN

Figure 28. Echo Read Clock and Read Enable Operation (IDT Standard mode, SDR to SDR, x40 In to x40 Out)

NOTES:

1. The EREN output is “or gated” to RCS and REN and will follow these inputs provided that the Queue is not empty. If the Queue is empty, EREN will go HIGH to indicate that

there is no new word available.

2. The EREN output is synchronous to RCLK.

3. OE = LOW, WDDR = HIGH, RDDR = HIGH, IS[1:0] = 00, and OS[1:0] = 00.

4. The truth table for EREN is shown below:

RCLK EF RCS REN EREN

↑1000

↑1011

↑1101

↑1111

↑0XX1

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

Figure 29. Echo RCLK and Echo Read Enable Operation (FWFT mode, SDR to SDR, x40 In to x40 Out)

NOTES:

1. The O/P Register is the internal output register. Its contents are available on the Qn output bus only when RCS and OE are both active, LOW, that is the bus is not in

High-Impedance state.

2. OE is LOW.

Cycle:

a&b. At this point the Queue is empty, OR0 is HIGH.

RCS and REN are both disabled, the output bus is High-Impedance.

c. Word Wn+1 falls through to the output register, OR0 goes active, LOW.

RCS is HIGH, therefore the Qn outputs are High-Impedance. EREN goes LOW to indicate that a new word has been placed into the output register.

d. EREN goes HIGH, no new word has been placed into the output register on this cycle.

e. No Operation.

f. RCS is LOW on this cycle, therefore the Qn outputs go to Low-Impedance and the contents of the output register (Wn+1) are made available.

NOTE: In FWFT mode it's important to take RCS active LOW at least one cycle ahead of REN, this ensures the word (Wn+1) currently in the output register is made

available for at least one cycle, otherwise Wn+1 will not be overwritten by Wn+2.

g. REN goes active LOW, this reads out the second word, Wn+2.

EREN goes active LOW to indicate a new word has been placed into the output register.

h. Word Wn+3 is read out, EREN remains active, LOW indicating a new word has been read out.

NOTE: Wn+3 is the last word in the Queue.

i. This is the next enabled read after the last word, Wn+3 has been read out. OR0 flag goes HIGH and EREN goes HIGH to indicate that there is no new word available.

4. OE = LOW, WDDR = LOW, RDDR = LOW, IS[1:0] = 00, and OS[1:0] = 00.

5. The truth table for EREN is shown below:

Q[39:0]

O/P

(1)

Reg.

REF

OR0

6159 drw36

RCSLZ

REN

ENS

ENH

RCS

ENS

RCLK abcdefghi

Wn+1

WCLK

WEN

D[39:0]

SKEW1

ENS

ENH

Wn+2 Wn+3

ERCLK

EREN

CLKEN

Wn+1 Wn+2 Wn+3

REF

Wn+1 Wn+2 Wn+3Wn Last Word

ERCLK

HIGH-Z

ENH

RCLK OR RCS REN EREN

↑0000

↑0011

↑0101

↑0111

↑1XX1

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

Figure 30. Echo Read Clock and Read Enable Operation (IDT Standard mode, DDR to DDR, x10 In to x10 Out)

NOTES:

1. The EREN output is “or gated” to RCS and REN and will follow these inputs provided that the Queue is not empty. If the Queue is empty, EREN will go HIGH to indicate that there is no new word available.

2. The EREN output is synchronous to RCLK.

3. OE = LOW, WDDR = HIGH, RDDR = HIGH, IS[1:0] = 00, and OS[1:0] = 00.

4. The truth table for EREN is shown below:

EREN

EF0

REF

Q[39:0]

CLKEN

OLZ

CLKEN

OLZ

WD-10 WD-9 WD-8 WD-6 WD-5 WD-4 WD-3 WD-2 Last Word W

6159 drw37

WD-7 WD-6

WD-1

RCLK

REN

ERCLK

RCS

ENS

ERCLK

ENH

ENS

ENH

CLKEN

ENS

NO Read NO Read

ENS

RCLK EF RCS REN EREN

↑1000

↑1011

↑1101

↑1111

↑0XX1

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

Figure 31. Loading of Programmable Flag Registers (IDT Standard and FWFT modes)

SENH

SDH

SCLK

SWEN

FWFT/SI

6159 drw38

EMPTY OFFSET 3 FULL OFFSET 3

SENS

SDS

BIT

(1)

BIT 1

SCL

SCKH

SCKL

BIT 1

(LSB)

EMPTY OFFSET 0 FULL OFFSET 0

BIT 1

(LSB)

BIT

(1)

BIT

(1)

BIT

(1)

(MSB)(MSB)

Figure 32. Reading of Programmable Flag Registers (IDT Standard and FWFT modes)

SCLK

SREN

SDO

6159 drw39

EMPTY OFFSET 3 FULL OFFSET 3

SENS

SOA

SEN

BIT X

(1)

SENH

SCLK

SCKH

SCKL

BIT 0

BIT X

(1)

BIT X

(1)

SOA

BIT 0

EMPTY OFFSET 0 FULL OFFSET 0

BIT 0

(LSB)

BIT X

(1)

(MSB) (LSB) (MSB)

NOTE:

1 . If IW/OW = x40, X = 104 for the IDT72T51248, X = 112 for the IDT72T51258, X = 120 for the IDT72T51268.

If IW/OW = x20, X = 112 for the IDT72T51248, X = 120 for the IDT72T51258, X = 128 for the IDT72T51268.

If IW/OW = x10, X = 120 for the IDT72T51248, X = 128 for the IDT72T51258, X = 136 for the IDT72T51268.

NOTE:

1 . If IW/OW = x40, X = 104 for the IDT72T51248, X = 112 for the IDT72T51258, X = 120 for the IDT72T51268.

If IW/OW = x20, X = 112 for the IDT72T51248, X = 120 for the IDT72T51258, X = 128 for the IDT72T51268.

If IW/OW = x10, X = 120 for the IDT72T51248, X = 128 for the IDT72T51258, X = 136 for the IDT72T51268.

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

WCLK

WEN

PAF0

RCLK

REN

6159 drw40

1212

D-(m0+1) words

in Queue(1)

D - m0 words in Queue(1)

D - (m0 +1) words in Queue(1)

tENH

tENS

tPAFS

tENS tENH

tCLKL

tSKEW2

(3)

tPAFS

tCLKL

WCLK

WEN

PAE0

RCLK

12 12

REN

6159 drw41

n0 + 1 words in Queue

(2)

n0 + 2 words in Queue

(3)

ENS

SKEW2(4)

ENH

PAES

n0 words in Queue

(2)

n0 + 1 words in Queue

(3)

PAES

n0 words in Queue

(2)

n0 + 1 words in Queue

(3)

ENS

ENH

CLKH

CLKL

NOTES:

1. m0 = PAF0 offset .

2. D = maximum Queue depth. For density of Queue with bus-matching, refer to the bus-matching section pages 17-20.

3. tSKEW2 is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that PAF0 will go HIGH (after one WCLK cycle plus tPAFS). If the time

between the rising edge of RCLK and the rising edge of WCLK is less than tSKEW2, then the PAF0 deassertion time may be delayed one extra WCLK cycle.

4. PAF0 is asserted and updated on the rising edge of WCLK only.

5. RCS = LOW, WCS = LOW, WDDR = LOW, RDDR = LOW, IS[1:0] = 00, and OS[1:0] = 00.

Figure 33. Synchronous Programmable Almost-Full Flag Timing (IDT Standard and FWFT mode, SDR to SDR, x40 In to x40 Out)

NOTES:

1 . n0 = PAE0 offset.

2. For IDT Standard mode

3. For FWFT mode.

tSKEW2 is the minimum time between a rising WCLK edge and a rising RCLK edge to guarantee that PAE will go HIGH (after one RCLK cycle plus tPAES). If the time between

the rising edge of WCLK and the rising edge of RCLK is less than tSKEW2, then the PAE

deassertion may be delayed one extra RCLK cycle.

5. PAE0 is asserted and updated on the rising edge of WCLK only.

6. RCS = LOW, WCS = LOW, WDDR = LOW, RDDR = LOW, IS[1:0] = 00, and OS[1:0] = 00.

Figure 34. Synchronous Programmable Almost-Empty Flag Timing (IDT Standard and FWFT mode, SDR to SDR, x40 In to x40 Out)

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

IDT72T51248/72T51258/72T51268 2.5V MULTI-QUEUE DDR FLOW-CONTROL DEVICES

8,192 x 40 x 4, 16,384 x 40 x 4 and 32,768 x 40 x 4

MARCH 22, 2005

Figure 35. Power Down Operation

6159 drw44

WCLK

WEN

D[39:0]

D10

D11

D13

RCLK

REN

ERCLK

PDHZ

(7)

PDLZ

(2)

PDL

PDH

(2)

PDH

(2)

(8)

Hi-Z

EREN

Q[39:0]

ERCLK

EREN

1234

(1)

1µs

EREN

D12

NOTES:

1. All read and write operations must have ceased a minimum of 4 WCLK and 4 RCLK cycles before power down is asserted.

2. When the PD input becomes deasserted, there will be a 1µs waiting period before read and write operations can resume.

All input and output signals will also resume after this time period.

3. Set-up and configuration static inputs are not affected during power down.

4. Serial programming and JTAG programming port are inactive during power down.

5. RCS = 0, WCS = 0 and OE = 0. These signals can toggle during and after power down.

6. All flags remain active and maintain their current states.

7. During power down, all outputs will be in high-impedance.

8. WDH = WD4 before power down.

CORPORATE HEADQUARTERS for SALES: for Tech Support:

6024 Silver Creek Valley Road 800-345-7015 or 408-284-8200 408-360-1533

San Jose, CA 95138 fax: 408-284-2775 email: Flow-Controlhelp@idt.com

www.idt.com

Plastic Ball Grid Array (PBGA, BB324-1)

Commercial (0°C to +70°C)

Industrial (-40°C to +85°C)

Low Power

6159drw45

Commercial Only

Commercial and Industrial

IDT XXXXX

Device Type

Power

Speed

Package

Process /

Temperature

Range

BLANK

(1)

72T51248 8,192 x 40 x 4  2.5V Multi-Queue DDR Flow-Control Device

72T51258 16,384 x 40 x 4  2.5V Multi-Queue DDR Flow-Control Device

72T51268 32,768 x 40 x 4  2.5V Multi-Queue DDR Flow-Control Device

Clock Cycle Time (t

CLK

)

Speed in Nanoseconds

6-7

ORDERING INFORMATION

NOTE:

1. Industrial temperature range product for the 6-7ns speed grade is available as a standard device. All other speed grades are available by special order.

DATASHEET DOCUMENT HISTORY

12/01/2003 pgs. 1, 5, 11, and 29.

03/22/2005 pgs. 1, 3, 6, 10-12, and 56.