ICS9248F-20 - Integrated Circuit Systems, Inc.

Integrated

Circuit

Systems, Inc.

General Description Features

ICS9248-20

Block Diagram

Pentium/ProTM System Clock Chip

9248-20 Rev B 12/03/98

Pin Configuration

48-Pin SSOP

Pentium is a trademark on Intel Corporation.

 Generates system clocks for CPU, IOAPIC, PCI, plus

14.314 MHz REF (0:2), USB, and Super I/O

 Supports single or dual processor systems

 Supports Spread Spectrum modulation for CPU & PCI

clocks, down spread -0.5%

 Skew from CPU (earlier) to PCI clock (rising edges for

100/33.3MHz) 1.5 to 4ns

 Two fixed outputs at 48MHz.

 Separate 2.5V and 3.3V supply pins

 2.5V or 3.3V output: CPU, IOAPIC

 3.3V outputs: PCI, REF, 48MHz

 No power supply sequence requirements

 Uses external 14.318MHz crystal, no external load cap

required for CL=18pF crystal

 48 pin 300 mil SSOP

The ICS9248-20 is a Clock Synthesizer chip for Pentium and

PentiumPro CPU based Desktop/Notebook systems that will

provide all necessary clock timing.

Features include four CPU and eight PCI clocks. Three

reference outputs are available equal to the crystal frequency.

Additionally, the device meets the Pentium power-up

stabilization requirement, assuring that CPU and PCI clocks

are stable within 2ms after power-up.

PD# pin enables low power mode by stopping crystal OSC

and PLL stages. Other power management features include

CPU_STOP#, which stops CPU (0:3) clocks, and PCI_STOP#,

which stops PCICLK (0:6) clocks.

High drive CPUCLK outputs typically provide greater than 1

V/ns slew rate into 20pF loads. PCICLK outputs typically

provide better than 1V/ns slew rate into 30pF loads while

maintaining 50±5% duty cycle. The REF clock outputs typically

provide better than 0.5V/ns slew rates.

The ICS9248-20 accepts a 14.318MHz reference crystal or

clock as its input and runs on a 3.3V core supply.

Power Groups

VDD = Supply for PLL core

VDD1 = REF (0:2), X1, X2

VDD2 = PCICLK_F, PCICLK (0:6)

VDD3 = 48MHz0, 48MHz1

VDDL1 = IOAPIC (0:1)

VDDL2 = CPUCLK (0:3)

Ground Groups

GND = Ground for PLL core

GND1 = REF (0:2), X1, X2

GND2 = PCICLK_F, PCICLK (0:6)

GND3 = 48MHz0, 48MHz1

GNDL1 = IOAPIC (0:1)

GNDL2 = CPUCLK (0:3)

ICS reserves the right to make changes in the device data identified in this

publication without further notice. ICS advises its customers to obtain the

latest version of all device data to verify that any information being relied

upon by the customer is current and accurate.

ICS9248-20

Pin Descriptions

Select Functions

Notes:

1. TCLK is a test clock driven on the X1 (crystal

in pin) input during test mode.

2. -0.5% modulation down spread from the

selected frequency.

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ICS9248-20

Technical Pin Function Descriptions

VDD(1,2,3)

This is the power supply to the internal core logic of the

device as well as the clock output buffers for REF(0:2),

PCICLK_F, PCICLK (0:6), 48MHz0, 48MHz1.

This pin operates at 3.3V volts. Clocks from the listed buffers

that it supplies will have a voltage swing from Ground to this

level. For the actual guaranteed high and low voltage levels

for the Clocks, please consult the DC parameter table in this

data sheet.

VDDL1,2

This is the power supply for the CPUCLK (0:3) and IOAPIC

output buffers. The voltage level for these outputs may be 2.5

or 3.3volts. Clocks from the buffers that each supplies will

have a voltage swing from Ground to this level. For the actual

Guaranteed high and low voltage levels of these Clocks,

please consult the DC parameter table in this Data Sheet.

GND (1,2,3)

This is the ground to the internal core logic of the device as

well as the clock output buffers for REF(0:2), PCICLK_F,

PCICLK (0:6), 48MHz 0, 48MHz1.

GNDL (1,2)

This is the ground for the CPUCLK (0:3) and IOAPIC output

buffers.

This input pin serves one of two functions. When the device

is used with a Crystal, X1 acts as the input pin for the

reference signal that comes from the discrete crystal. When

the device is driven by an external clock signal, X1 is the

device input pin for that reference clock. This pin also

implements an internal Crystal loading capacitor that is

connected to ground. With a nominal value of 33pF no

external load cap is needed for a CL=17 to 18pF crystal.

This Output pin is used only when the device uses a Crystal as

the reference frequency source. In this mode of operation, X2

is an output signal that drives (or excites) the discrete Crystal.

The X2 pin will also implement an internal Crystal loading

capacitor nominally 33pF.

CPUCLK (0:3)

These Output pins are the Clock Outputs that drive processor

and other CPU related circuitry that requires clocks which are

in tight skew tolerance with the CPU clock. The voltage

swing of these Clocks is controlled by the Voltage level

applied to the VDDL2 pin of the device. See the Functionality

Table for a list of the specific frequencies that are available

for these Clocks and the selection codes to produce them.

48MHz (0:1)

This is a fixed frequency Clock output that is typically used to

drive Super I/O devices. Outputs 0 and 1 are defined as

48MHz.

IOAPIC (0:1)

This Output is a fixed frequency Output Clock that runs at the

Reference Input (typically 14.31818MHz) . Its voltage level

swing is controlled by VDDL1 and may operate at 2.5 or

3.3volts.

REF(0:2)

The REF Outputs are fixed frequency Clocks that run at the

same frequency as the Input Reference Clock X1 or the

Crystal (typically 14.31818MHz) attached across X1 and X2.

PCICLK_F

This Output is equal to PCICLK(0:6) and is FREE RUNNING,

and will not be stopped by PCI_STOP#.

PCICLK (0:6)

These Output Clocks generate all the PCI timing requirements

for a Pentium/Pro based system. They conform to the current

PCI specification. They run at 33.3 MHz.

SELECT 100/66.6MHz#

This Input pin controls the frequency of the Clocks at the

CPUCLK, PCICLK and SDRAM output pins. If a logic 1

value is present on this pin, the 100MHz Clock will be

selected. If a logic 0 is used, the 66.6MHz frequency will

be selected. The PCI clock is multiplexed to be 33.3MHz for

both select cases. PCI is synchronous at the rising edge of PCI

to the CPU rising edge (with the skew making CPU early).

PWR_DWN#

This is an asynchronous active Low Input pin used to Power

Down the device into a Low Power state by not removing the

power supply. The internal Clocks are disabled and the VCO

and Crystal are stopped. Powered Down will also place all

the Outputs in a low state at the end of their current cycle. The

latency of Power Down will not be greater than 3ms.

CPU_STOP#

This is a synchronous active Low Input pin used to stop the

CPUCLK clocks in an active low state. All other Clocks

including SDRAM clocks will continue to run while this

function is enabled. The CPUCLKs will have a turn ON

latency of at least 3 CPU clocks.

PCI_STOP#

This is a synchronous active Low Input pin used to stop the

PCICLK clocks in an active low state. It will not affect

PCICLK_F nor any other outputs.

ICS9248-20

Power Management

ICS9248-20 Power Management Requirements

Clock Enable Configuration

Full clock cycle timing is guaranteed at all times after the system has initially powered up except where noted. During power up

and power down operations using the PD# select pin will not cause clocks of a shorter or longer pulse than that of the running

clock. The first clock pulse coming out of a stopped clock condition may be slightly distorted due to clock network charging

circuitry. Board routing and signal loading may have a large impact on the initial clock distortion also.

Notes.

1. Clock on latency is defined from when the clock enable goes active to when the first valid clock comes out of the device.

2. Clock off latency is defined from when the clock enable goes inactive to when the last clock is driven low out of the device.

3. Power up latency is when PD# goes inactive (high) to when the first valid clocks are output by the device.

4. Power down has controlled clock counts applicable to CPUCLK, PCICLK only.

The REF and IOAPIC will be stopped independent of these.

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ICS9248-20

PCI_ST OP# Timing Diagram

PCI_STOP# is an asynchronous input to the ICS9248-20. It is used to turn off the PCICLK (0:6) clocks for low power operation.

PCI_STOP# is synchronized by the ICS9248-20 internally. The minimum that the PCICLK (0:6) clocks are enabled

(PCI_STOP# high pulse) is at least 10 PCICLK (0:6) clocks. PCICLK (0:6) clocks are stopped in a low state and started with

a full high pulse width guaranteed. PCICLK (0:6) clock on latency cycles are only one rising PCICLK. Clock off latency is one

PCICLK clock.

CPU_ST OP# Timing Diagram

CPUSTOP# is an asychronous input to the clock synthesizer. It is used to turn off the CPUCLKs for low power operation.

CPU_STOP# is synchronized by the ICS9248-20. The minimum that the CPUCLK is enabled (CPU_STOP# high pulse) is 100

CPUCLKs. All other clocks will continue to run while the CPUCLKs are disabled. The CPUCLKs will always be stopped in a

low state and start in such a manner that guarantees the high pulse width is a full pulse. CPUCLK on latency is less than 4

CPUCLKs and CPUCLK off latency is less than 4 CPUCLKs.

Notes:

1. All timing is referenced to the internal CPUCLK.

2. CPU_STOP# is an asynchronous input and metastable conditions may exist. This

signal is synchronized to the CPUCLKs inside the ICS9248-20.

3. All other clocks continue to run undisturbed.

4. PD# and PCI_STOP# are shown in a high (true) state.

Notes:

1. All timing is referenced to the Internal CPUCLK (defined as inside the ICS9148 device.)

2. PCI_STOP# is an asynchronous input, and metastable conditions may exist. This signal is required to be synchronized

inside the ICS9248-20.

3. All other clocks continue to run undisturbed.

4. PD# and CPU_STOP# are shown in a high (true) state.

ICS9248-20

PD# Timing Diagram

The power down selection is used to put the part into a very low power state without turning off the power to the part. PD# is

an asynchronous active low input. This signal is synchronized internally by the ICS9248-20 prior to its control action of

powering down the clock synthesizer. Internal clocks will not be running after the device is put in power down state. When PD#

is active (low) all clocks are driven to a low state and held prior to turning off the VCOs and the Crystal oscillator. The power

on latency is guaranteed to be less than 3ms. The power down latency is less than three CPUCLK cycles. PCI_STOP# and

CPU_STOP# are dont care signals during the power down operations.

Notes:

1. All timing is referenced to the Internal CPUCLK (defined as inside the ICS9148 device).

2. PD# is an asynchronous input and metastable conditions may exist. This signal is synchronized inside the ICS9148.

3. The shaded sections on the VCO and the Crystal signals indicate an active clock is being generated.

ICS9248-20

Absolute Maximum Ratings

Supply Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . 7.0 V

Logic Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GND 0.5 V to VDD +0.5 V

Ambient Operating Temperature . . . . . . . . . . . . 0°C to +70°C

Storage Temperature . . . . . . . . . . . . . . . . . . . . . . 65°C to +150°C

Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. These ratings are stress

specifications only and functional operation of the device at these or any other conditions above those listed in the operational

sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect

product reliability.

Elec t ri c al Ch ar a cter ist ics - I nput/Supply/Com m on Out p ut Pa ram eter s

TA = 0 - 70C; Supply Voltage VDD = VDDL = 3.3 V +/-5% (unles s otherwis e state d)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Input High Voltage VIH 2V

DD+0.3 V

Input L ow Voltage VIL VSS-0.3 0.8 V

Input High Curr ent I

N = VDD 0.1 5 µA

Input Low Current I

L1 V

N = 0 V; I nputs with no pull-up res istors - 5 2. 0 µA

Input Low Current IIL2 VIN = 0 V; Inputs with pull-up r es istors -200 -100 µA

Operating IDD3.3OP66 CL = 0 pF ; Sele ct @ 66MHz 60 170 m A

Supply Cur rent IDD3.3OP100 CL = 0 pF; S e le ct @ 100MHz 66 170 m A

Pow er Down

Supply Cur rent IDD3.3PD CL = 0 pF ; With input addres s to Vdd or GND 70 600 µA

Input frequenc y F

VDD = 3.3 V; 11 14.318 16 MHz

CIN Logic Inputs 5 pF

CINX X1 & X2 pins 27 36 45 pF

Tr ansition Time1T

rans To 1st crossing of ta rget Freq. 3 ms

Settling Ti me1T

F rom 1s t crossing to 1% target F req. 5 m s

Clk Stabilization1TSTAB From VDD = 3.3 V to 1% target Fr e q. 3 m s

Skew1TCPU-PCI1 VT = 1.5 V; 1.5 3 4 ns

1Guarantee d by de sign, not 100% t e sted i n produc t ion.

Input Capacitanc e1

Elect ri cal Character i sti cs - I nput/ Suppl y/Com mon O utput Paramet ers

TA = 0 - 70C; Supply Volta ge VDD = 3.3 V + / -5% , VDDL = 2. 5 V +/-5% (unles s ot herwis e s ta ted )

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Operating IDD2.5OP66 CL = 0 pF ; Sele c t @ 66.8 M Hz 16 72 mA

Supply Current IDD2.5OP100 CL = 0 pF; Sele c t @ 100 MHz 23 100 mA

Skew1tCPU-PCI2 VT = 1. 5 V; VTL = 1.25 V 1.5 3 4 ns

1Guara nte e d by de sign, not 100% teste d in production .

ICS9248-20

Elect ri cal Char acter i sti cs - CPUCLK

TA = 0 - 70C; VDD = 3.3 V +/-5%, VDDL = 2. 5 V +/-5%; C L = 10 - 20 pF ( u nle ss oth e rwise stat e d)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Output High Voltage VOH2B IOH = -12. 0 mA 2 2.3 V

Output Low Voltage VOL2B IOL = 12 m A 0.2 0.4 V

Output High C urre nt I OH2B VOH = 1.7 V -41 -19 mA

Output Low Cu rrent IOL2B VOL = 0.7 V 19 37 m A

Rise T im e t

2B1VOL = 0. 4 V, VOH = 2.0 V 1.25 1.6 ns

Fall T ime tf2B1VOH = 2.0 V, VOL = 0.4 V 1 1.6 ns

Duty Cycle d

2B1VT = 1.25 V 454855%

Skew t

k2B1VT = 1.25 V 30 175 ps

J itte r, Cycle-to-cycle tjcyc-cyc2B1VT = 1. 25 V 150 200 ps

J itte r, One Sigm a tj1s2B1VT = 1.25 V 40 150 ps

J itte r, Absolute tjabs2B1VT = 1.25 V -250 140 +250 ps

1Guara nteed by d e sign, not 100% te ste d in product ion .

Electr ical Character isti cs - I O A PIC

TA = 0 - 70C; VDD = 3. 3 V +/-5% , VDDL = 2. 5 V +/- 5% ; C L = 20 pF

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Output High Voltage VOH4B IOH = -18 mA 2 2. 2 V

Output Low Voltage VOL4B IOL = 18 mA 0. 33 0.4 V

Output H ig h Cur rent I OH4B VOH = 1. 7 V -41 - 28 mA

Output L ow Cu rrent I OL4B VOL = 0. 7 V 29 37 m A

Rise Time1Tr4B VOL = 0. 4 V, VOH = 2.0 V 1.5 2 ns

Fall Time1Tf4B VOH = 2.0 V, VOL = 0.4 V 1.3 2 ns

Duty Cycle1Dt4B VT = 1.25 V 455455%

Skew1tsk4B1VT = 1. 25 V 60 250 ps

J itte r, One Sigma1Tj1s4B VT = 1. 25 V 1 3 %

J itter, Abs olute1Tjabs4B VT = 1. 25 V -5 5 %

1Guarante e d by d esign, not 100% tested in production .

ICS9248-20

Electri cal Characteri stics - PCICLK

TA = 0 - 70C; VDD = VDDL = 3. 3 V +/- 5%; C L = 30 pF

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Output High Voltage VOH1 IOH = -11 mA 2.4 3.1 V

Output Low Voltage VOL1 IOL = 9 . 4 mA 0. 1 0. 4 V

Output High Curr e nt IOH1 VOH = 2.0 V -62 - 22 mA

Output L ow C ur rent I OL1 VOL = 0. 8 V 16 57 mA

Rise T im e1t

1VOL = 0.4 V, VOH = 2.4 V 1.5 2 ns

Fall T ime1t

1VOH = 2.4 V, VOL = 0.4 V 1.1 2 ns

Duty Cycle1d

1VT = 1.5 V 455055%

Skew1tsk1 VT = 1. 5 V 140 500 ps

J itte r, One Sigma1tj1s1 VT = 1. 5 V 17 150 ps

J itte r, Absolute 1tjabs1 VT = 1. 5 V -500 70 500 ps

1Guarantee d by design, not 100% tested in produc tion.

Electr ical Character isti cs - REF

TA = 0 - 70C; VDD = VDDL = 3.3 V + /-5%; CL = 10 - 20 pF ( un less othe rwise s ta te d)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Output High Voltage VOH5 IOH = -12 mA 2.6 3. 1 V

Output Low Voltage VOL5 IOL = 9 m A 0. 17 0.4 V

Output H ig h Curr e nt I OH5 VOH = 2. 0 V -44 - 22 mA

Output L ow Cu rrent I OL5 VOL = 0. 8 V 29 42 mA

Rise Tim e1t

5VOL = 0.4 V, VOH = 2.4 V 1.4 2 ns

Fall Time1t

5VOH = 2.4 V, VOL = 0.4 V 1.1 2 ns

Duty Cycle1d

5VT = 1.5 V 455355%

J itte r, One Sigma1tj1s5 VT = 1. 5 V 1 3 %

J itter, A b so lute1tjabs5 VT = 1.5 V 35%

1Guarante e d by d esign, not 100% tested in production .

ICS9248-20

Electr ical Characteri stics - 48 M Hz

TA = 0 - 70C; VDD = VDDL = 3.3 V +/-5%; CL = 10 - 20 pF ( un less othe rwis e s ta te d)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Fr equency A c cur acy1FACC48m 167 ppm

Output High Voltage VOH5 IOH = -12 mA 2. 6 3 V

Output Low Voltage VOL5 IOL = 9 mA 0. 14 0. 4 V

Output H ig h Curr e nt I OH5 VOH = 2. 0 V -44 - 22 mA

Output L ow Cu rrent I OL5 VOL = 0. 8 V 16 42 mA

Ris e Tim e1tr5 VOL = 0.4 V, VOH = 2.4 V 1.2 4 ns

Fall Time1tf5 VOH = 2.4 V, VOL = 0.4 V 1.2 4 ns

Duty Cycle1dt5 VT = 1.5 V 455255%

J itte r, One Sigma1tj1s5 VT = 1. 5 V 1 3 %

J itter, Abs olute 1tjabs5 VT = 1.5 V 35%

1Guara ntee d by d esign, not 100% tes te d in produc tion.

ICS9248-20

Ordering Information

ICS9248F-20

Pattern Number (2 or 3 digit number for parts with ROM code patterns)

Package Type

F=SSOP

Device Type (consists of 3 or 4 digit numbers)

Prefix

ICS, AV = Standard Device

Example:

ICS XXXX F - PPP

This table in inches

SSOP Package

LOBMYS SNOISNEMIDNOMMOC SNOITAIRAV D N

.NIM.MON.XAM.NIM.MON.XAM

A590.101.011.CA026.526.036.84

1A800.210.610.DA027.527.037.65

2A880.090.290.

B800.010.5310.

C500.600.5800.

DsnoitairaVeeS

E292.692.992.

eCSB520.0

H004.604.014.

h010.310.610.

L420.230.040.

NsnoitairaVeeS

°0°5°8

X580.390.001.

ICS reserves the right to make changes in the device data identified in this

publication without further notice. ICS advises its customers to obtain the

latest version of all device data to verify that any information being relied

upon by the customer is current and accurate.