CY14B108K, CY14B108M
8 Mbit (1024K x 8/512K x 16) nvSRAM with
Real Time Clock
Cypress Semiconductor Corporation • 198 Champion Court • San Jose,CA 95134-1709 • 408-943-2600
Document #: 001-47378 Rev. *D Revised December 15, 2009
Features
■25 ns and 45 ns Access Times
■Internally Organized as 1024K x 8 (CY14B108K) or 512K x 16
(CY14B108M)
■Hands Off Automatic STORE on Power Down with only a Small
Capacitor
■STORE to QuantumTrap Nonvolatile Elements is Initiated by
Software, Device Pin, or AutoStore on Power Down
■RECALL to SRAM Initiated by Software or Power Up
■High Reliability
■Infinite Read, Write, and RECALL Cycles
■1 Million STORE Cycles to QuantumTrap
■20 year Data Retention
■Single 3V +20%, –10% Operation
■Data Integrity of Cypress nvSRAM Combined with Full
Featured Real Time Clock (RTC)
■Watchdog Timer
■Clock Alarm with Programmable Interrupts
■Capacitor or Battery Backup for RTC
■Industrial Temperature
■44 and 54-pin TSOP II Package
■Pb-free and RoHS Compliance
Functional Description
The Cypress CY14B108K/CY14B108M combines a 8-Mbit
nonvolatile static RAM with a full featured RTC in a monolithic
integrated circuit. The embedded nonvolatile elements incor-
porate QuantumTrap technology producing the world’s most
reliable nonvolatile memory. The SRAM is read and written
infinite number of times, while independent nonvolatile data
resides in the nonvolatile elements.
The RTC function provides an accurate clock with leap year
tracking and a programmable, high accuracy oscillator. The
alarm function is programmable for periodic minutes, hours,
days, or months alarms. There is also a programmable watchdog
timer for process control.
STATIC RAM
ARRAY
2048 X 2048 X 2
R
O
W
D
E
C
O
D
E
R
COLUMN I/O
COLUMN DEC
I
N
P
U
T
B
U
F
F
E
R
S
POWER
CONTROL
STORE/RECALL
CONTROL
Quatrum
Trap
2048 X 2048 X 2
STORE
RECALL
VCC VCAP
HSB
A9A10 A11 A12 A13 A14 A15 A16
SOFTWARE
DETECT A14 -A
2
OE
CE
WE
BHE
BLE
A0
A1
A2
A3
A4
A5
A6
A7
A8
A17
A18
DQ0
DQ1
DQ2
DQ3
DQ4
DQ5
DQ6
DQ7
DQ8
DQ9
DQ10
DQ11
DQ12
DQ13
DQ14
DQ15
RTC
MUX A19-A
0
Xout
Xin
INT
VRTCbat
VRTCcap
A19
Logic Block Diagram[1, 2, 3]
Notes
1. Address A0 - A19 for x8 configuration and Address A0 - A18 for x16 configuration.
2. Data DQ0 - DQ7 for x8 configuration and Data DQ0 - DQ15 for x16 configuration.
3. BHE and BLE are applicable for x16 configuration only.
[+] Feedback
CY14B108K, CY14B108M
Document #: 001-47378 Rev. *D Page 2 of 31
Contents
Features .............................................................................. 1
Functional Description ...................................................... 1
Logic Block Diagram[1, 2, 3] ............................................ 1
Contents ............................................................................. 2
Pinouts ............................................................................... 3
Device Operation ............................................................... 4
SRAM Read ........................................................................ 4
SRAM Write ........................................................................ 4
AutoStore Operation ......................................................... 4
Hardware STORE (HSB) Operation .................................. 5
Hardware RECALL (Power Up) ......................................... 5
Software STORE ................................................................ 5
Software RECALL .............................................................. 5
Preventing AutoStore ........................................................ 6
Data Protection .................................................................. 7
Noise Considerations ........................................................ 7
Best Practices .................................................................... 7
Real Time Clock Operation ............................................... 8
nvTime Operation......................................................... 8
Clock Operations.......................................................... 8
Reading the Clock ........................................................ 8
Setting the Clock .......................................................... 8
Backup Power .............................................................. 8
Stopping and Starting the Oscillator............................. 8
Calibrating the Clock .................................................... 9
Alarm ............................................................................ 9
Watchdog Timer ........................................................... 9
Power Monitor ............................................................ 10
Interrupts .................................................................... 10
Flags Register ............................................................ 10
Maximum Ratings .............................................................16
Operating Range ...............................................................16
DC Electrical Characteristics ..........................................16
Data Retention and Endurance .......................................17
Capacitance ......................................................................17
Thermal Resistance ..........................................................17
AC Test Conditions ..........................................................17
RTC Characteristics .........................................................18
AC Switching Characteristics .........................................19
Switching Waveforms ......................................................19
Switching Waveforms ......................................................20
Switching Waveforms ......................................................21
AutoStore/Power Up RECALL .........................................22
Switching Waveforms ......................................................22
Software Controlled STORE and RECALL Cycle ..........23
Hardware STORE Cycle ...................................................24
Truth Table For SRAM Operations ..................................25
For x8 Configuration.................................................... 25
For x16 Configuration.................................................. 25
Part Numbering Nomenclature ........................................26
Ordering Information ........................................................27
Package Diagrams ............................................................28
Document History Page ...................................................30
Sales, Solutions, and Legal Information ........................31
Worldwide Sales and Design Support......................... 31
Products .......................................................................31
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CY14B108K, CY14B108M
Document #: 001-47378 Rev. *D Page 3 of 31
Note
4. Address expansion for 16 Mbit. NC pin not connected to die.
Pinouts
Figure 1. Pin Diagram: 44-PIn and 54-Pin TSOP II
Table 1. Pin Definitions
Pin Name I/O Type Description
A0 – A19 Input Address Inputs Used to Select one of the 1,048,576 bytes of the nvSRAM for x8 Configuration.
A0 – A18 Address Inputs Used to Select one of the 524,288 words of the nvSRAM for x16 Configuration.
DQ0 – DQ7Input/Output Bidirectional Data I/O Lines for x8 Configuration. Used as input or output lines depending on
operation.
DQ0 – DQ15 Bidirectional Data I/O Lines for x16 Configuration. Used as input or output lines depending on
operation.
NC No Connect No Connects. This pin is not connected to the die.
WE Input Write Enable Input, Active LOW. When selected LOW, data on the I/O pins is written to the specific
address location.
CE Input Chip Enable Input, Active LOW. When LOW, selects the chip. When HIGH, deselects the chip.
OE Input Output Enable, Active LOW. The active LOW OE input enables the data output buffers during read
cycles. Deasserting OE HIGH causes the I/O pins to tristate.
BHE Input Byte High Enable, Active LOW. Controls DQ15 - DQ8.
BLE Input Byte Low Enable, Active LOW. Controls DQ7 - DQ0.
Xout Output Crystal Connection. Drives crystal on start up.
Xin Input Crystal Connection. For 32.768 KHz crystal.
VRTCcap Power Supply Capacitor Supplied Backup RTC Supply Voltage. Left unconnected if VRTCbat is used.
VRTCbat Power Supply Battery Supplied Backup RTC Supply Voltage. Left unconnected if VRTCcap is used.
INT Output Interrupt Output. Programmable to respond to the clock alarm, the watchdog timer, and the power
monitor. Also programmable to either active HIGH (push or pull) or LOW (open drain).
VSS Ground Ground for the Device. Must be connected to ground of the system.
NC
A
8
Xin
Xout
V
SS
DQ
6
DQ5
DQ4
V
CC
A
13
DQ
3
A
12
DQ
2
DQ
1
DQ
0
OE
A
9
CE
NC
A
0
A
1
A
2
A
3
A
4
A
5
A
6
A
11
A
7
A
14
A
15
A
16
A
19
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22 23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
44 - TSOP II
Top View
(not to scale)
A
10
V
RTCbat
WE
DQ
7
HSB
INT
V
SS
V
CC
V
CAP
V
RTCcap
(x8)
DQ
7
DQ
6
DQ
5
DQ
4
V
CC
DQ
3
DQ
2
DQ
1
DQ
0
NC
A
0
A
1
A
2
A
3
A
4
A
5
A
6
A
7
V
CAP
WE
A
8
A
10
A
11
A
12
A
13
A
14
A
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27 28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
54 - TSOP II
Top View
(not to scale)
OE
CE
V
CC
INT
V
SS
NC
A
9
NC
A
18
54
53
52
51
49
50
HSB
BHE
BLE
DQ
15
DQ
14
DQ
13
DQ
12
V
SS
DQ
11
DQ
10
DQ
9
DQ
8
(x16)
V
RTCcap
V
RTCbat
Xin
Xout
[4]
[4]
A
17
A
18
A
16
A
17
[+] Feedback
CY14B108K, CY14B108M
Document #: 001-47378 Rev. *D Page 4 of 31
Device Operation
The CY14B108K/CY14B108M nvSRAM is made up of two
functional components paired in the same physical cell. These
are a SRAM memory cell and a nonvolatile QuantumTrap cell.
The SRAM memory cell operates as a standard fast static RAM.
Data in the SRAM is transferred to the nonvolatile cell (the
STORE operation), or from the nonvolatile cell to the SRAM (the
RECALL operation). Using this unique architecture, all cells are
stored and recalled in parallel. During the STORE and RECALL
operations SRAM read and write operations are inhibited. The
CY14B108K/CY14B108M supports infinite reads and writes
similar to a typical SRAM. In addition, it provides infinite RECALL
operations from the nonvolatile cells and up to 1 million STORE
operations. See the Truth Table For SRAM Operations on page
25 for a complete description of read and write modes.
SRAM Read
The CY14B108K/CY14B108M performs a read cycle whenever
CE and OE are LOW, and WE and HSB are HIGH. The address
specified on pins A0-19 or A0-18 determines which of the
1,048,576 data bytes or 524,288 words of 16 bits each are
accessed. Byte enables (BHE, BLE) determine which bytes are
enabled to the output, in the case of 16-bit words. When the read
is initiated by an address transition, the outputs are valid after a
delay of tAA (read cycle 1). If the read is initiated by CE or OE,
the outputs are valid at tACE or at tDOE, whichever is later (read
cycle 2). The data output repeatedly responds to address
changes within the tAA access time without the need for transi-
tions on any control input pins. This remains valid until another
address change or until CE or OE is brought HIGH, or WE or
HSB is brought LOW.
SRAM Write
A write cycle is performed when CE and WE are LOW and HSB
is HIGH. The address inputs must be stable before entering the
write cycle and must remain stable until CE or WE goes HIGH at
the end of the cycle. The data on the common I/O pins DO0-15
are written into the memory if it is valid tSD before the end of a
WE controlled write or before the end of a CE controlled write.
The Byte Enable inputs (BHE, BLE) determine which bytes are
written, in the case of 16-bit words. Keep OE HIGH during the
entire write cycle to avoid data bus contention on common I/O
lines. If OE is left LOW, internal circuitry turns off the output
buffers tHZWE after WE goes LOW.
AutoStore Operation
The CY14B108K/CY14B108M stores data to the nvSRAM using
one of three storage operations. These three operations are:
Hardware STORE, activated by the HSB; Software STORE,
activated by an address sequence; AutoStore, on device power
down. The AutoStore operation is a unique feature of
QuantumTrap technology and is enabled by default on the
CY14B108K/CY14B108M.
During normal operation, the device draws current from VCC to
charge a capacitor connected to the VCAP pin. This stored
charge is used by the chip to perform a single STORE operation.
If the voltage on the VCC pin drops below VSWITCH, the part
automatically disconnects the VCAP pin from VCC. A STORE
operation is initiated with power provided by the VCAP capacitor.
Note If the capacitor is not connected to VCAP pin, AutoStore
must be disabled using the soft sequence specified in Preventing
AutoStore on page 6. In case AutoStore is enabled without a
capacitor on VCAP pin, the device attempts an AutoStore
operation without sufficient charge to complete the Store. This
may corrupt the data stored in nvSRAM.
Figure 2. AutoStore Mode
Figure 2 shows the proper connection of the storage capacitor
(VCAP) for automatic STORE operation. Refer to DC Electrical
Characteristics on page 16 for the size of the VCAP
. The voltage
on the VCAP pin is driven to VCC by a regulator on the chip. A pull
up should be placed on WE to hold it inactive during power up.
This pull up is only effective if the WE signal is tristate during
power up. Many MPUs tristate their controls on power up. Verify
this when using the pull up. When the nvSRAM comes out of
power-on-recall, the MPU must be active or the WE held inactive
until the MPU comes out of reset.
VCC Power Supply Power Supply Inputs to the Device. 3.0V +20%, –10%.
HSB
Input/Output Hardware STORE Busy (HSB). When LOW this output indicates that a Hardware STORE is in progress.
When pulled LOW external to the chip it initiates a nonvolatile STORE operation. A weak internal pull
up resistor keeps this pin HIGH if not connected (connection optional). After each STORE operation
HSB is driven HIGH for short time with standard output high current.
VCAP Power Supply AutoStore Capacitor. Supplies power to the nvSRAM during power loss to store data from SRAM to
nonvolatile elements.
Table 1. Pin Definitions (continued)
Pin Name I/O Type Description
0.1uF
VCC
10kOhm
VCAP
WE VCAP
VSS
VCC
[+] Feedback
CY14B108K, CY14B108M
Document #: 001-47378 Rev. *D Page 5 of 31
To reduce unnecessary nonvolatile STOREs, AutoStore, and
Hardware STORE operations are ignored unless at least one
write operation has taken place since the most recent STORE or
RECALL cycle. Software initiated STORE cycles are performed
regardless of whether a write operation has taken place. The
HSB signal is monitored by the system to detect if an AutoStore
cycle is in progress.
Hardware STORE (HSB) Operation
The CY14B108K/CY14B108M provides the HSB pin to control
and acknowledge the STORE operations. The HSB pin is used
to request a Hardware STORE cycle. When the HSB pin is driven
LOW, the CY14B108K/CY14B108M conditionally initiates a
STORE operation after tDELAY
. An actual STORE cycle begins
only if a write to the SRAM has taken place since the last STORE
or RECALL cycle. The HSB pin also acts as an open drain driver
that is internally driven LOW to indicate a busy condition when
the STORE (initiated by any means) is in progress.
SRAM write operations that are in progress when HSB is driven
LOW by any means are given time (tDELAY) to complete before
the STORE operation is initiated. However, any SRAM write
cycles requested after HSB goes LOW are inhibited until HSB
returns HIGH. In case the write latch is not set, HSB is not driven
LOW by the CY14B108K/CY14B108M. But any SRAM read and
write cycles are inhibited until HSB is returned HIGH by MPU or
other external source.
During any STORE operation, regardless of how it is initiated,
the CY14B108K/CY14B108M continues to drive the HSB pin
LOW, releasing it only when the STORE is complete. Upon
completion of the STORE operation, the
CY14B108K/CY14B108M remains disabled until the HSB pin
returns HIGH. Leave the HSB unconnected if it is not used.
Hardware RECALL (Power Up)
During power up or after any low power condition
(VCC<V
SWITCH), an internal RECALL request is latched. When
VCC again exceeds the VSWITCH on powerup, a RECALL cycle
is automatically initiated and takes tHRECALL to complete. During
this time, the HSB pin is driven LOW by the HSB driver and all
reads and writes to nvSRAM are inhibited.
Software STORE
Data is transferred from the SRAM to the nonvolatile memory by
a software address sequence. The CY14B108K/CY14B108M
Software STORE cycle is initiated by executing sequential CE or
OE controlled read cycles from six specific address locations in
exact order. During the STORE cycle, an erase of the previous
nonvolatile data is first performed, followed by a program of the
nonvolatile elements. After a STORE cycle is initiated, further
input and output are disabled until the cycle is completed.
Because a sequence of reads from specific addresses is used
for STORE initiation, it is important that no other read or write
accesses intervene in the sequence, or the sequence is aborted
and no STORE or RECALL takes place.
To initiate the Software STORE cycle, the following read
sequence must be performed:
1. Read address 0x4E38 Valid READ
2. Read address 0xB1C7 Valid READ
3. Read address 0x83E0 Valid READ
4. Read address 0x7C1F Valid READ
5. Read address 0x703F Valid READ
6. Read address 0x8FC0 Initiate STORE cycle
The software sequence may be clocked with CE controlled reads
or OE controlled reads, with WE kept HIGH for all the six READ
sequences. After the sixth address in the sequence is entered,
the STORE cycle commences and the chip is disabled. HSB is
driven LOW. After the tSTORE cycle time is fulfilled, the SRAM is
activated again for the read and write operation.
Software RECALL
Data is transferred from the nonvolatile memory to the SRAM by
a software address sequence. A software RECALL cycle is
initiated with a sequence of read operations in a manner similar
to the Software STORE initiation. To initiate the RECALL cycle,
perform the following sequence of CE or OE controlled read
operations:
1. Read address 0x4E38 Valid READ
2. Read address 0xB1C7 Valid READ
3. Read address 0x83E0 Valid READ
4. Read address 0x7C1F Valid READ
5. Read address 0x703F Valid READ
6. Read address 0x4C63 Initiate RECALL cycle
Internally, RECALL is a two step procedure. First, the SRAM data
is cleared; then, the nonvolatile information is transferred into the
SRAM cells. After the tRECALL cycle time, the SRAM is again
ready for read and write operations. The RECALL operation
does not alter the data in the nonvolatile elements.
[+] Feedback
CY14B108K, CY14B108M
Document #: 001-47378 Rev. *D Page 6 of 31
Preventing AutoStore
The AutoStore function is disabled by initiating an AutoStore
disable sequence. A sequence of read operations is performed
in a manner similar to the Software STORE initiation. To initiate
the AutoStore disable sequence, the following sequence of CE
or OE controlled read operations must be performed:
1. Read address 0x4E38 Valid READ
2. Read address 0xB1C7 Valid READ
3. Read address 0x83E0 Valid READ
4. Read address 0x7C1F Valid READ
5. Read address 0x703F Valid READ
6. Read address 0x8B45 AutoStore Disable
AutoStore is re-enabled by initiating an AutoStore enable
sequence. A sequence of read operations is performed in a
manner similar to the software RECALL initiation. To initiate the
AutoStore enable sequence, the following sequence of CE or OE
controlled read operations must be performed:
1. Read address 0x4E38 Valid READ
2. Read address 0xB1C7 Valid READ
3. Read address 0x83E0 Valid READ
4. Read address 0x7C1F Valid READ
5. Read address 0x703F Valid READ
6. Read address 0x4B46 AutoStore Enable
If the AutoStore function is disabled or re-enabled, a manual
STORE operation (hardware or software) issued to save the
AutoStore state through subsequent power down cycles. The
part comes from the factory with AutoStore enabled.
Table 2. Mode Selection
CE WE OE, BHE, BLE[3] A15 - A0[5] Mode I/O Power
H X X X Not Selected Output High Z Standby
L H L X Read SRAM Output Data Active
L L X X Write SRAM Input Data Active
L H L 0x4E38
0xB1C7
0x83E0
0x7C1F
0x703F
0x8B45
Read SRAM
Read SRAM
Read SRAM
Read SRAM
Read SRAM
AutoStore
Disable
Output Data
Output Data
Output Data
Output Data
Output Data
Output Data
Active[6]
L H L 0x4E38
0xB1C7
0x83E0
0x7C1F
0x703F
0x4B46
Read SRAM
Read SRAM
Read SRAM
Read SRAM
Read SRAM
AutoStore
Enable
Output Data
Output Data
Output Data
Output Data
Output Data
Output Data
Active[6]
L H L 0x4E38
0xB1C7
0x83E0
0x7C1F
0x703F
0x8FC0
Read SRAM
Read SRAM
Read SRAM
Read SRAM
Read SRAM
Nonvolatile
STORE
Output Data
Output Data
Output Data
Output Data
Output Data
Output High Z
Active ICC2[6]
L H L 0x4E38
0xB1C7
0x83E0
0x7C1F
0x703F
0x4C63
Read SRAM
Read SRAM
Read SRAM
Read SRAM
Read SRAM
Nonvolatile
RECALL
Output Data
Output Data
Output Data
Output Data
Output Data
Output High Z
Active[6]
Notes
5. While there are 20 address lines on the CY14B108K (19 address lines on the CY14B108M), only the 13 address lines (A14 - A2) are used to control software modes.
The remaining address lines are don’t care.
6. The six consecutive address locations must be in the order listed. WE must be HIGH during all six cycles to enable a nonvolatile cycle.
[+] Feedback
CY14B108K, CY14B108M
Document #: 001-47378 Rev. *D Page 7 of 31
Data Protection
The CY14B108K/CY14B108M protects data from corruption
during low voltage conditions by inhibiting all externally initiated
STORE and write operations. The low voltage condition is
detected when VCC is less than VSWITCH. If the
CY14B108K/CY14B108M is in a write mode (both CE and WE
are LOW) at power up, after a RECALL or STORE, the write is
inhibited until the SRAM is enabled after tLZHSB (HSB to output
active). This protects against inadvertent writes during power up
or brown out conditions.
Noise Considerations
Refer to CY application note AN1064.
Best Practices
nvSRAM products have been used effectively for over 15 years.
While ease-of-use is one of the product’s main system values,
experience gained working with hundreds of applications has
resulted in the following suggestions as best practices:
■The nonvolatile cells in this nvSRAM product are delivered from
Cypress with 0x00 written in all cells. Incoming inspection
routines at customer or contract manufacturer’s sites
sometimes reprogram these values. Final NV patterns are
typically repeating patterns of AA, 55, 00, FF, A5, or 5A. End
product’s firmware should not assume an NV array is in a set
programmed state. Routines that check memory content
values to determine first time system configuration, cold or
warm boot status, and so on should always program a unique
NV pattern (that is, complex 4-byte pattern of 46 E6 49 53 hex
or more random bytes) as part of the final system manufac-
turing test to ensure these system routines work consistently.
■Power up boot firmware routines should rewrite the nvSRAM
into the desired state (for example, autostore enabled). While
the nvSRAM is shipped in a preset state, best practice is to
again rewrite the nvSRAM into the desired state as a safeguard
against events that might flip the bit inadvertently such as
program bugs and incoming inspection routines.
■The VCAP value specified in this data sheet includes a minimum
and a maximum value size. Best practice is to meet this
requirement and not exceed the maximum VCAP value because
the nvSRAM internal algorithm calculates VCAP charge and
discharge time based on this maximum VCAP value. Customers
that want to use a larger VCAP value to make sure there is extra
store charge and store time should discuss their VCAP size
selection with Cypress to understand any impact on the VCAP
voltage level at the end of a tRECALL period.
[+] Feedback
CY14B108K, CY14B108M
Document #: 001-47378 Rev. *D Page 8 of 31
Real Time Clock Operation
nvTime Operation
The CY14B108K/CY14B108M offers internal registers that
contain clock, alarm, watchdog, interrupt, and control functions.
RTC registers use the last 16 address locations of the SRAM.
Internal double buffering of the clock and timer information
registers prevents accessing transitional internal clock data
during a read or write operation. Double buffering also
circumvents disrupting normal timing counts or the clock
accuracy of the internal clock when accessing clock data. Clock
and alarm registers store data in BCD format.
RTC functionality is described with respect to CY14B108K in the
following sections. The same description applies to
CY14B108M, except for the RTC register addresses. The RTC
register addresses for CY14B108K range from 0xFFFF0 to
0xFFFFF, while those for CY14B108M range from 0x7FFF0 to
0x7FFFF. Refer to Tab l e 4 on page 12 and Tabl e 5 on page 13
for a detailed Register Map description.
Clock Operations
The clock registers maintain time up to 9,999 years in one
second increments. The time can be set to any calendar time and
the clock automatically keeps track of days of the week and
month, leap years, and century transitions. There are eight
registers dedicated to the clock functions, which are used to set
time with a write cycle and to read time during a read cycle.
These registers contain the time of day in BCD format. Bits
defined as ‘0’ are currently not used and are reserved for future
use by Cypress.
Reading the Clock
The double buffered RTC register structure reduces the chance
of reading incorrect data from the clock. The user must stop
internal updates to the CY14B108K time keeping registers
before reading clock data, to prevent reading of data in transition.
Stopping the register updates does not affect clock accuracy.
The updating process is stopped by writing a ‘1’ to the read bit
‘R’ (in the flags register at 0xFFFF0), and does not restart until a
‘0’ is written to the read bit. The RTC registers are then read while
the internal clock continues to run. After a ‘0’ is written to the read
bit (‘R’), all RTC registers are simultaneously updated within
20 ms
Setting the Clock
Setting the write bit ‘W’ (in the flags register at 0xFFFF0) to a ‘1’
stops updates to the time keeping registers and enables the time
to be set. The correct day, date, and time is then written into the
registers and must be in 24 hour BCD format. The time written is
referred to as the “Base Time”. This value is stored in nonvolatile
registers and used in the calculation of the current time.
Resetting the write bit to ‘0’ transfers the values of timekeeping
registers to the actual clock counters, after which the clock
resumes normal operation.
If the time written to the timekeeping registers is not in the correct
BCD format, each invalid nibble of the RTC registers continue
counting to 0xF before rolling over to 0x0 after which RTC
resumes normal operation.
Note The values entered in the timekeeping, alarm, calibration,
and interrupt registers need a STORE operation to be saved in
nonvolatile memory. Therefore, while working in AutoStore
disabled mode, the user must perform a STORE operation after
writing into the RTC registers for the RTC to work correctly.
Backup Power
The RTC in the CY14B108K is intended for permanently
powered operation. The VRTCcap or VRTCbat pin is connected
depending on whether a capacitor or battery is chosen for the
application. When the primary power, VCC, fails and drops below
VSWITCH the device switches to the backup power supply.
The clock oscillator uses very little current, which maximizes the
backup time available from the backup source. Regardless of the
clock operation with the primary source removed, the data stored
in the nvSRAM is secure, having been stored in the nonvolatile
elements when power was lost.
During backup operation, the CY14B108K consumes 0.35
microamps (Typ) at room temperature. User must choose
capacitor or battery values according to the application.
Backup time values based on maximum current specifications
are shown in the following table. Nominal backup times are
approximately two times longer.
Using a capacitor has the obvious advantage of recharging the
backup source each time the system is powered up. If a battery
is used, a 3V lithium is recommended and the CY14B108K
sources current only from the battery when the primary power is
removed. However, the battery is not recharged at any time by
the CY14B108K. The battery capacity must be chosen for total
anticipated cumulative down time required over the life of the
system.
Stopping and Starting the Oscillator
The OSCEN bit in the calibration register at 0xFFFF8 controls
the enable and disable of the oscillator. This bit is nonvolatile and
is shipped to customers in the “enabled” (set to 0) state. To
preserve the battery life when the system is in storage, OSCEN
must be set to ‘1’. This turns off the oscillator circuit, extending
the battery life. If the OSCEN bit goes from disabled to enabled,
it takes approximately one second (two seconds maximum) for
the oscillator to start.
While system power is off, If the voltage on the backup supply
(VRTCcap or VRTCbat) falls below their respective minimum level,
the oscillator may fail.The CY14B108K has the ability to detect
oscillator failure when system power is restored. This is recorded
in the OSCF (Oscillator Failed bit) of the flags register at the
address 0xFFFF0. When the device is powered on (VCC goes
above VSWITCH) the OSCEN bit is checked for “enabled” status.
If the OSCEN bit is enabled and the oscillator is not active within
the first 5 ms, the OSCF bit is set to “1”. The system must check
for this condition and then write ‘0’ to clear the flag. Note that in
addition to setting the OSCF flag bit, the time registers are reset
to the “Base Time” (see Setting the Clock on page 8), which is
the value last written to the timekeeping registers. The control or
calibration registers and the OSCEN bit are not affected by the
‘oscillator failed’ condition.
Table 3. RTC Backup Time
Capacitor Value Backup Time
0.1F 72 hours
0.47F 14 days
1.0F 30 days
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CY14B108K, CY14B108M
Document #: 001-47378 Rev. *D Page 9 of 31
The value of OSCF must be reset to ‘0’ when the time registers
are written for the first time. This initializes the state of this bit
which may have become set when the system was first powered
on.
To reset OSCF, set the write bit “W” (in the Flags register at
0xFFFF0) to a “1” to enable writes to the Flag register. Write a
“0” to the OSCF bit and then reset the write bit to “0” to disable
writes.
Calibrating the Clock
The RTC is driven by a quartz controlled crystal with a nominal
frequency of 32.768 kHz. Clock accuracy depends on the quality
of the crystal and calibration. The crystals available in market
typically have an error of +20 ppm to +35 ppm. However,
CY14B108K employs a calibration circuit that improves the
accuracy to +1/–2 ppm at 25°C. This implies an error of +2.5
seconds to -5 seconds per month.
The calibration circuit adds or subtracts counts from the oscillator
divider circuit to achieve this accuracy. The number of pulses that
are suppressed (subtracted, negative calibration) or split (added,
positive calibration) depends upon the value loaded into the five
calibration bits found in Calibration register at 0xFFFF8. The
calibration bits occupy the five lower order bits in the Calibration
register. These bits are set to represent any value between ‘0’
and 31 in binary form. Bit D5 is a sign bit, where a ‘1’ indicates
positive calibration and a ‘0’ indicates negative calibration.
Adding counts speeds the clock up and subtracting counts slows
the clock down. If a binary ‘1’ is loaded into the register, it corre-
sponds to an adjustment of 4.068 or –2.034 ppm offset in oscil-
lator error, depending on the sign.
Calibration occurs within a 64-minute cycle. The first 62 minutes
in the cycle may, once every minute, have one second shortened
by 128 or lengthened by 256 oscillator cycles. If a binary ‘1’ is
loaded into the register, only the first two minutes of the
64-minute cycle are modified. If a binary 6 is loaded, the first 12
are affected, and so on. Therefore, each calibration step has the
effect of adding 512 or subtracting 256 oscillator cycles for every
125,829,120 actual oscillator cycles, that is, 4.068 or –2.034 ppm
of adjustment per calibration step in the Calibration register.
To determine the required calibration, the CAL bit in the Flags
register (0xFFFF0) must be set to ‘1’. This causes the INT pin to
toggle at a nominal frequency of 512 Hz. Any deviation
measured from the 512 Hz indicates the degree and direction of
the required correction. For example, a reading of 512.01024 Hz
indicates a +20 ppm error. Hence, a decimal value of –10
(001010b) must be loaded into the Calibration register to offset
this error.
Note Setting or changing the Calibration register does not affect
the test output frequency.
To set or clear CAL, set the write bit “W” (in the flags register at
0xFFFF0) to “1” to enable writes to the Flag register. Write a
value to CAL, and then reset the write bit to “0” to disable writes.
Alarm
The alarm function compares user programmed values of alarm
time and date (stored in the registers 0xFFFF1-5) with the corre-
sponding time of day and date values. When a match occurs, the
alarm internal flag (AF) is set and an interrupt is generated on
INT pin if Alarm Interrupt Enable (AIE) bit is set.
There are four alarm match fields - date, hours, minutes, and
seconds. Each of these fields has a match bit that is used to
determine if the field is used in the alarm match logic. Setting the
match bit to ‘0’ indicates that the corresponding field is used in
the match process. Depending on the match bits, the alarm
occurs as specifically as once a month or as frequently as once
every minute. Selecting none of the match bits (all 1s) indicates
that no match is required and therefore, alarm is disabled.
Selecting all match bits (all 0s) causes an exact time and date
match.
There are two ways to detect an alarm event: by reading the AF
flag or monitoring the INT pin. The AF flag in the flags register at
0xFFFF0 indicates that a date or time match has occurred. The
AF bit is set to “1” when a match occurs. Reading the flags
register clears the alarm flag bit (and all others). A hardware
interrupt pin may also be used to detect an alarm event.
To set, clear or enable an alarm, set the ‘W’ bit (in Flags Register
- 0xFFFF0) to ‘1’ to enable writes to Alarm Registers. After
writing the alarm value, clear the ‘W’ bit back to “0” for the
changes to take effect.
Note CY14B108K requires the alarm match bit for seconds
(0xFFFF2 - D7) to be set to ‘0’ for proper operation of Alarm Flag
and Interrupt.
Watchdog Timer
The Watchdog Timer is a free running down counter that uses
the 32 Hz clock (31.25 ms) derived from the crystal oscillator.
The oscillator must be running for the watchdog to function. It
begins counting down from the value loaded in the Watchdog
Timer register.
The timer consists of a loadable register and a free running
counter. On power up, the watchdog time out value in register
0xFFFF7 is loaded into the Counter Load register. Counting
begins on power up and restarts from the loadable value any time
the Watchdog Strobe (WDS) bit is set to ‘1’. The counter is
compared to the terminal value of ‘0’. If the counter reaches this
value, it causes an internal flag and an optional interrupt output.
You can prevent the time out interrupt by setting WDS bit to ‘1’
prior to the counter reaching ‘0’. This causes the counter to
reload with the watchdog time out value and to be restarted. As
long as the user sets the WDS bit prior to the counter reaching
the terminal value, the interrupt and WDT flag never occur.
New time out values are written by setting the watchdog write bit
to ‘0’. When the WDW is ‘0’, new writes to the watchdog time out
value bits D5-D0 are enabled to modify the time out value. When
WDW is ‘1’, writes to bits D5-D0 are ignored. The WDW function
enables a user to set the WDS bit without concern that the
watchdog timer value is modified. A logical diagram of the
watchdog timer is shown in Figure 3. Note that setting the
watchdog time out value to ‘0’ disables the watchdog function.
The output of the watchdog timer is the flag bit WDF that is set if
the watchdog is allowed to time out. If the Watchdog Interrupt
Enable (WIE) bit in the Interrupt register is set, a hardware
interrupt on INT pin is also generated on watchdog timeout. The
flag and the hardware interrupt are both cleared when user reads
the Flags registers.
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CY14B108K, CY14B108M
Document #: 001-47378 Rev. *D Page 10 of 31
Figure 3. Watchdog Timer Block Diagram
.
Power Monitor
The CY14B108K provides a power management scheme with
power fail interrupt capability. It also controls the internal switch
to backup power for the clock and protects the memory from low
VCC access. The power monitor is based on an internal band gap
reference circuit that compares the VCC voltage to VSWITCH
threshold.
As described in the section AutoStore Operation on page 4,
when VSWITCH is reached as VCC decays from power loss, a data
STORE operation is initiated from SRAM to the nonvolatile
elements, securing the last SRAM data state. Power is also
switched from VCC to the backup supply (battery or capacitor) to
operate the RTC oscillator.
When operating from the backup source, read and write opera-
tions to nvSRAM are inhibited and the clock functions are not
available to the user. The clock continues to operate in the
background. The updated clock data is available to the user
tHRECALL delay after VCC is restored to the device (see
AutoStore/Power Up RECALL on page 22)
Interrupts
The CY14B108K has Flags register, Interrupt register, and
Interrupt logic that can signal interrupt to the microcontroller.
There are three potential sources for interrupt: watchdog timer,
power monitor, and alarm timer. Each of these can be individually
enabled to drive the INT pin by appropriate setting in the Interrupt
register (0xFFFF6). In addition, each has an associated flag bit
in the Flags register (0xFFFF0) that the host processor uses to
determine the cause of the interrupt. The INT pin driver has two
bits that specify its behavior when an interrupt occurs.
An Interrupt is raised only if both a flag is raised by one of the
three sources and the respective interrupt enable bit in Interrupts
register is enabled (set to ‘1’). After an interrupt source is active,
two programmable bits, H/L and P/L, determine the behavior of
the output pin driver on INT pin. These two bits are located in the
Interrupt register and can be used to drive level or pulse mode
output from the INT pin. In pulse mode, the pulse width is
internally fixed at approximately 200 ms. This mode is intended
to reset a host microcontroller. In the level mode, the pin goes to
its active polarity until the Flags register is read by the user. This
mode is used as an interrupt to a host microcontroller. The
control bits are summarized in the following section.
Interrupts are only generated while working on normal power and
are not triggered when system is running in backup power mode.
Note CY14B108K generates valid interrupts only after the
Powerup Recall sequence is completed. All events on INT pin
must be ignored for tHRECALL duration after powerup.
Interrupt Register
Watchdog Interrupt Enable (WIE). When set to ‘1’, the
watchdog timer drives the INT pin and an internal flag when a
watchdog time out occurs. When WIE is set to ‘0’, the watchdog
timer only affects the WDF flag in Flags register.
Alarm Interrupt Enable (AIE). When set to ‘1’, the alarm match
drives the INT pin and an internal flag. When AIE is set to ‘0’, the
alarm match only affects the AF Flags register.
Power Fail Interrupt Enable (PFE). When set to ‘1’, the power
fail monitor drives the pin and an internal flag. When PFE is set
to ‘0’, the power fail monitor only affects the PF flag in Flags
register.
High/Low (H/L). When set to a ‘1’, the INT pin is active HIGH
and the driver mode is push pull. The INT pin drives high only
when VCC is greater than VSWITCH. When set to a ‘0’, the INT pin
is active LOW and the drive mode is open drain. The INT pin
must be pulled up to Vcc by a 10k resistor while using the
interrupt in active LOW mode.
Pulse/Level (P/L). When set to a ‘1’ and an interrupt occurs, the
INT pin is driven for approximately 200 ms. When P/L is set to a
‘0’, the INT pin is driven high or low (determined by H/L) until the
Flags or Control register is read.
When an enabled interrupt source activates the INT pin, an
external host reads the Flags registers to determine the cause.
Remember that all flags are cleared when the register is read. If
the INT pin is programmed for Level mode, then the condition
clears and the INT pin returns to its inactive state. If the pin is
programmed for Pulse mode, then reading the flag also clears
the flag and the pin. The pulse does not complete its specified
duration if the Flags register is read. If the INT pin is used as a
host reset, the Flags register is not read during a reset
Flags Register
The Flag register has three flag bits: WDF, AF, and PF, which can
be used to generate an interrupt. They are set by the watchdog
timeout, alarm match, or power fail monitor respectively. The
processor can either poll this register or enable interrupts when
a flag is set. These flags are automatically reset when the
register is read. The flags register is automatically loaded with
the value 0x00 on power up (except for the OSCF bit. See
Stopping and Starting the Oscillator on page 8)
1 Hz
Oscillator Clock
Divider
Counter Zero
Compare WDF
WDS Load
Register
WDW
DQ
Q
Watchdog
Register
write to
Watchdog
Register
32 Hz
32,768 KHz
[+] Feedback
CY14B108K, CY14B108M
Document #: 001-47378 Rev. *D Page 11 of 31
Figure 4. RTC Recommended Component Configuration
Figure 5. Interrupt Block Diagram
Xout
Xin
Y1
C2
C1
Watchdog
Timer
Power
Monitor
Clock
Alarm
VINT
WDF
WIE
PF
PFE
AF
AIE
P/L
Pin
Driver
H/L
INT
V
CC
V
SS
WDF - Watchdog Timer Flag
WIE - Watchdog Interrupt
PF - Power Fail Flag
PFE - Power Fail Enable
AF - Alarm Flag
AIE - Alarm Interrupt Enable
P/L - Pulse Level
H/L - High/Low
Enable
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CY14B108K, CY14B108M
Document #: 001-47378 Rev. *D Page 12 of 31
Table 4. RTC Register Map[7]
Register BCD Format Data[8]
Function/Range
CY14B108K CY14B108M D7 D6 D5 D4 D3 D2 D1 D0
0xFFFFF 0x7FFFF 10s Years Years Years: 00–99
0xFFFFE 0x7FFFE 0 0 0 10s
Months
Months Months: 01–12
0xFFFFD 0x7FFFD 0 0 10s Day of Month Day Of Month Day of Month: 01–31
0xFFFFC 0x7FFFC 0 0 0 0 0 Day of week Day of week: 01–07
0xFFFFB 0x7FFFB 0 0 10s Hours Hours Hours: 00–23
0xFFFFA 0x7FFFA 0 10s Minutes Minutes Minutes: 00–59
0xFFFF9 0x7FFF9 0 10s Seconds Seconds Seconds: 00–59
0xFFFF8 0x7FFF8 OSCEN
(0)
0Cal Sign
(0)
Calibration (00000) Calibration Values [9]
0xFFFF7 0x7FFF7 WDS
(0)
WDW (0) WDT (000000) Watchdog [9]
0xFFFF6 0x7FFF6 WIE (0) AIE (0) PFE (0) 0 H/L
(1)
P/L (0) 0 0 Interrupts [9]
0xFFFF5 0x7FFF5 M (1) 0 10s Alarm Date Alarm Day Alarm, Day of Month:
01–31
0xFFFF4 0x7FFF4 M (1) 0 10s Alarm Hours Alarm Hours Alarm, Hours: 00–23
0xFFFF3 0x7FFF3 M (1) 10 Alarm Minutes Alarm Minutes Alarm, Minutes:
00–59
0xFFFF2 0x7FFF2 M (1) 10 Alarm Seconds Alarm, Seconds Alarm, Seconds:
00–59
0xFFFF1 0x7FFF1 10s Centuries Centuries Centuries: 00–99
0xFFFF0 0x7FFF0 WDF AF PF OSCF 0 CAL (0) W (0) R (0) Flags [9]
Notes
7. Upper Byte D15-D8 (CY14B108M) of RTC registers are reserved for future use
8. ( ) designates values shipped from the factory.
9. This is a binary value, not a BCD value.
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CY14B108K, CY14B108M
Document #: 001-47378 Rev. *D Page 13 of 31
Table 5. Register Map Detail
Register Description
CY14B108K CY14B108M
0xFFFFF 0x7FFFF Time Keeping - Years
D7 D6 D5 D4 D3 D2 D1 D0
10s Years Years
Contains the lower two BCD digits of the year. Lower nibble (four bits) contains the value for years;
upper nibble (four bits) contains the value for 10s of years. Each nibble operates from 0 to 9. The
range for the register is 0–99.
0xFFFFE 0x7FFFE
Time Keeping - Months
D7 D6 D5 D4 D3 D2 D1 D0
0 0 0 10s Month Months
Contains the BCD digits of the month. Lower nibble (four bits) contains the lower digit and operates
from 0 to 9; upper nibble (one bit) contains the upper digit and operates from 0 to 1. The range
for the register is 1–12.
0xFFFFD 0x7FFFD Time Keeping - Date
D7 D6 D5 D4 D3 D2 D1 D0
0 0 10s Day of Month Day of Month
Contains the BCD digits for the date of the month. Lower nibble (four bits) contains the lower digit
and operates from 0 to 9; upper nibble (two bits) contains the 10s digit and operates from 0 to 3.
The range for the register is 1–31. Leap years are automatically adjusted for.
0xFFFFC 0x7FFFC Time Keeping - Day
D7 D6 D5 D4 D3 D2 D1 D0
0 0 0 0 0 Day of Week
Lower nibble (three bits) contains a value that correlates to day of the week. Day of the week is a
ring counter that counts from 1 to 7 then returns to 1. The user must assign meaning to the day
value, because the day is not integrated with the date.
0xFFFFB 0x7FFFB Time Keeping - Hours
D7 D6 D5 D4 D3 D2 D1 D0
0 0 10s Hours Hours
Contains the BCD value of hours in 24 hour format. Lower nibble (four bits) contains the lower
digit and operates from 0 to 9; upper nibble (two bits) contains the upper digit and operates from
0 to 2. The range for the register is 0–23.
0xFFFFA 0x7FFFA Time Keeping - Minutes
D7 D6 D5 D4 D3 D2 D1 D0
0 10s Minutes Minutes
Contains the BCD value of minutes. Lower nibble (four bits) contains the lower digit and operates
from 0 to 9; upper nibble (three bits) contains the upper minutes digit and operates from 0 to 5.
The range for the register is 0–59.
0xFFFF9 0x7FFF9 Time Keeping - Seconds
D7 D6 D5 D4 D3 D2 D1 D0
0 10s Seconds Seconds
Contains the BCD value of seconds. Lower nibble (four bits) contains the lower digit and operates
from 0 to 9; upper nibble (three bits) contains the upper digit and operates from 0 to 5. The range
for the register is 0 to 59.
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CY14B108K, CY14B108M
Document #: 001-47378 Rev. *D Page 14 of 31
Register Description
CY14B108K CY14B108M
0xFFFF8 0x7FFF8 Calibration/Control
D7 D6 D5 D4 D3 D2 D1 D0
OSCEN 0 Calibration
Sign
Calibration
OSCEN Oscillator Enable. When set to 1, the oscillator is stopped. When set to 0, the oscillator runs.
Disabling the oscillator saves battery or capacitor power during storage.
Calibration
Sign
Determines if the calibration adjustment is applied as an addition (1) to or as a subtraction (0) from
the time-base.
Calibration These five bits control the calibration of the clock.
0xFFFF7 0x7FFF7 WatchDog Timer
D7 D6 D5 D4 D3 D2 D1 D0
WDS WDW WDT
WDS Watchdog Strobe. Setting this bit to 1 reloads and restarts the watchdog timer. Setting the bit to
0 has no effect. The bit is cleared automatically after the watchdog timer is reset. The WDS bit is
write only. Reading it always returns a 0.
WDW Watchdog Write Enable. Setting this bit to 1 disables any WRITE to the watchdog timeout value
(D5–D0). This allows the user to set the watchdog strobe bit without disturbing the timeout value.
Setting this bit to 0 allows bits D5–D0 to be written to the watchdog register when the next write
cycle is complete. This function is explained in more detail in Watchdog Timer on page 9.
WDT Watchdog timeout selection. The watchdog timer interval is selected by the 6-bit value in this
register. It represents a multiplier of the 32 Hz count (31.25 ms). The range of timeout value is
31.25 ms (a setting of 1) to 2 seconds (setting of 3 Fh). Setting the watchdog timer register to 0
disables the timer. These bits can be written only if the WDW bit was set to 0 on a previous cycle.
0xFFFF6 0x7FFF6
Interrupt Status/Control
D7 D6 D5 D4 D3 D2 D1 D0
WIE AIE PFE 0 H/L P/L 0 0
WIE Watchdog Interrupt Enable. When set to 1 and a watchdog timeout occurs, the watchdog timer
drives the INT pin and the WDF flag. When set to 0, the watchdog timeout affects only the WDF
flag.
AIE Alarm Interrupt Enable. When set to 1, the alarm match drives the INT pin and the AF flag. When
set to 0, the alarm match only affects the AF flag.
PFE Power Fail Enable. When set to 1, the power fail monitor drives the INT pin and the PF flag. When
set to 0, the power fail monitor affects only the PF flag.
0 Reserved for future use
H/L High/Low. When set to 1, the INT pin is driven active HIGH. When set to 0, the INT pin is open
drain, active LOW.
P/L Pulse/Level. When set to 1, the INT pin is driven active (determined by H/L) by an interrupt source
for approximately 200 ms. When set to 0, the INT pin is driven to an active level (as set by H/L)
until the flags register is read.
0xFFFF5 0x7FFF5 Alarm - Day
D7 D6 D5 D4 D3 D2 D1 D0
M 0 10s Alarm Date Alarm Date
Contains the alarm value for the date of the month and the mask bit to select or deselect the date
value.
M Match. When this bit is set to 0, the date value is used in the alarm match. Setting this bit to 1
causes the match circuit to ignore the date value.
Table 5. Register Map Detail (continued)
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CY14B108K, CY14B108M
Document #: 001-47378 Rev. *D Page 15 of 31
Register Description
CY14B108K CY14B108M
0xFFFF4 0x7FFF4 Alarm - Hours
D7 D6 D5 D4 D3 D2 D1 D0
M 0 10s Alarm Hours Alarm Hours
Contains the alarm value for the hours and the mask bit to select or deselect the hours value.
M Match. When this bit is set to 0, the hours value is used in the alarm match. Setting this bit to 1
causes the match circuit to ignore the hours value.
0xFFFF3 0x7FFF3 Alarm - Minutes
D7 D6 D5 D4 D3 D2 D1 D0
M 10s Alarm Minutes Alarm Minutes
Contains the alarm value for the minutes and the mask bit to select or deselect the minutes value.
M Match. When this bit is set to 0, the minutes value is used in the alarm match. Setting this bit to 1
causes the match circuit to ignore the minutes value.
0xFFFF2 0x7FFF2 Alarm - Seconds
D7 D6 D5 D4 D3 D2 D1 D0
M 10s Alarm Seconds Alarm Seconds
Contains the alarm value for the seconds and the mask bit to select or deselect the seconds’ value.
M Match. When this bit is set to 0, the seconds value is used in the alarm match. Setting this bit to
1 causes the match circuit to ignore the seconds value.
0xFFFF1 0x7FFF1 Time Keeping - Centuries
D7 D6 D5 D4 D3 D2 D1 D0
10s Centuries Centuries
Contains the BCD value of centuries. Lower nibble contains the lower digit and operates from 0
to 9; upper nibble contains the upper digit and operates from 0 to 9. The range for the register is
0-99 centuries.
0xFFFF0 0x7FFF0 Flags
D7 D6 D5 D4 D3 D2 D1 D0
WDF AF PF OSCF 0 CAL W R
WDF Watchdog Timer Flag. This read only bit is set to 1 when the watchdog timer is allowed to reach
0 without being reset by the user. It is cleared to 0 when the Flags register is read or on power up
AF Alarm Flag. This read only bit is set to 1 when the time and date match the values stored in the
alarm registers with the match bits = 0. It is cleared when the Flags register is read or on power up.
PF Power Fail Flag. This read only bit is set to 1 when power falls below the power fail threshold
VSWITCH. It is cleared to 0 when the Flags register is read or on power up.
OSCF Oscillator Fail Flag. Set to 1 on power up if the oscillator is enabled and not running in the first 5
ms of operation. This indicates that RTC backup power failed and clock value is no longer valid.
This bit survives power cycle and is never cleared internally by the chip. The user must check for
this condition and write '0' to clear this flag.
CAL Calibration Mode. When set to 1, a 512 Hz square wave is output on the INT pin. When set to 0,
the INT pin resumes normal operation. This bit defaults to 0 (disabled) on power up.
W Write Enable: Setting the W bit to 1 freezes updates of the RTC registers. The user can then write
to RTC registers, Alarm registers, Calibration register, Interrupt register and Flags register. Setting
the W bit to 0 causes the contents of the RTC registers to be transferred to the time keeping
counters if the time is changed (a new base time is loaded). This bit defaults to 0 on power up.
R Read Enable: Setting R bit to 1, stops clock updates to user RTC registers so that clock updates
are not seen during the reading process. Set R bit to 0 to resume clock updates to the holding
register. Setting this bit does not require W bit to be set to 1. This bit defaults to 0 on power up.
Table 5. Register Map Detail (continued)
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CY14B108K, CY14B108M
Document #: 001-47378 Rev. *D Page 16 of 31
Maximum Ratings
Exceeding maximum ratings may impair the useful life of the
device. These user guidelines are not tested.
Storage Temperature ................................. –65°C to +150°C
Maximum Accumulated Storage Time
At 150°C Ambient Temperature................................... 1000h
At 85°C Ambient Temperature..................... ........... 20 Years
Ambient Temperature with
Power Applied ............................................ –55°C to +150°C
Supply Voltage on VCC Relative to GND ..........–0.5V to 4.1V
Voltage Applied to Outputs
in High Z State ....................................... –0.5V to VCC + 0.5V
Input Voltage...........................................–0.5V to Vcc + 0.5V
Transient Voltage (<20 ns) on
Any Pin to Ground Potential .................. –2.0V to VCC + 2.0V
Package Power Dissipation
Capability (TA = 25°C) ................................................... 1.0W
Surface Mount Pb Soldering
Temperature (3 Seconds) .......................................... +260°C
DC Output Current (1 output at a time, 1s duration).....15 mA
Static Discharge Voltage.......................................... > 2001V
(per MIL-STD-883, Method 3015)
Latch Up Current ................................................... > 200 mA
Operating Range
Range Ambient Temperature VCC
Industrial –40°C to +85°C 2.7V to 3.6V
DC Electrical Characteristics
Over the Operating Range (VCC = 2.7V to 3.6V)
Parameter Description Test Conditions Min Typ[10] Max Unit
VCC Power Supply 2.7 3.0 3.6 V
ICC1 Average VCC Current tRC = 25 ns
tRC = 45 ns
Values obtained without output loads (IOUT = 0 mA)
75
57
mA
mA
ICC2 Average VCC Current
during STORE
All Inputs Don’t Care, VCC = Max.
Average current for duration tSTORE
20 mA
ICC3 Average VCC Current
at tRC = 200 ns,
VCC (Typ), 25°C
All Inputs Cycling at CMOS Levels.
Values obtained without output loads (IOUT = 0 mA).
40 mA
ICC4 Average VCAP
Current during
AutoStore Cycle
All Inputs Don’t Care. Average current for duration tSTORE 10 mA
ISB VCC Standby Current CE > (VCC – 0.2V). VIN < 0.2V or > (VCC – 0.2V). W bit set
to ‘0’. Standby current level after nonvolatile cycle is
complete. Inputs are static. f = 0 MHz.
10 mA
IIX[11] Input Leakage
Current (except
HSB)
VCC = Max, VSS < VIN < VCC –2 +2 μA
Input Leakage
Current (for HSB)
VCC = Max, VSS < VIN < VCC –200 +2 μA
IOZ Off State Output
Leakage Current
VCC = Max, VSS < VOUT < VCC, CE or OE > VIH or BHE/BLE
> VIH or WE < VIL
–2 +2 μA
VIH Input HIGH Voltage 2.0 VCC + 0.5 V
VIL Input LOW Voltage Vss – 0.5 0.8 V
VOH Output HIGH Voltage IOUT = –2 mA 2.4 V
VOL Output LOW Voltage IOUT = 4 mA 0.4 V
VCAP Storage Capacitor Between VCAP pin and VSS, 5V Rated 122 150 360 μF
Notes
10. Typical values are at 25°C, VCC= VCC (Typ). Not 100% tested.
11. The HSB pin has IOUT = -2 uA for VOH of 2.4V when both active HIGH and LOW drivers are disabled. When they are enabled standard VOH and VOL are valid. This
parameter is characterized but not tested.
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Document #: 001-47378 Rev. *D Page 17 of 31
AC Test Conditions
Input Pulse Levels ....................................................0V to 3V
Input Rise and Fall Times (10% - 90%) ........................ <3 ns
Input and Output Timing Reference Levels .................... 1.5V
Data Retention and Endurance
Parameter Description Min Unit
DATARData Retention 20 Years
NVCNonvolatile STORE Operations 1,000 K
Capacitance
In the following table, the capacitance parameters are listed. [12]
Parameter Description Test Conditions Max Unit
CIN Input Capacitance TA = 25°C, f = 1 MHz,
VCC = VCC (Typ)
14 pF
COUT Output Capacitance 14 pF
Thermal Resistance
In the following table, the thermal resistance parameters are listed.[12]
Parameter Description Test Conditions 44 TSOP II 54 TSOP II Unit
ΘJA Thermal Resistance
(Junction to Ambient)
Test conditions follow standard test
methods and procedures for
measuring thermal impedance, in
accordance with EIA/JESD51.
31.11 30.73 °C/W
ΘJC Thermal Resistance
(Junction to Case)
5.56 6.08 °C/W
Figure 6. AC Test Loads
3.0V
OUTPUT
5 pF
R1
R2
789Ω
3.0V
OUTPUT
30 pF
R1
R2
789Ω
577Ω577Ω
Note
12. These parameters are only guaranteed by design and are not tested.
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Document #: 001-47378 Rev. *D Page 18 of 31
RTC Characteristics
Parameters Description Min Typ[10] Max Units
VRTCbat RTC Battery Pin Voltage 1.8 3.0 3.6 V
IBAK[13] RTC Backup Current TA (Min) 0.35 μA
25°C 0.35 μA
TA (Max) 0.5 μA
VRTCcap[14] RTC Capacitor Pin Voltage TA (Min) 1.6 3.6 V
25°C 1.5 3.0 3.6 V
TA (Max) 1.4 3.6 V
tOCS RTC Oscillator Time to Start 1 2 sec
RBKCHG RTC Backup Capacitor Charge Current -Limiting
Resistor
350 850 Ω
Notes
13. From either VRTCcap or VRTCbat.
14. If VRTCcap > 0.5V or if no capacitor is connected to VRTCcap pin, the oscillator starts in tOCS time. If a backup capacitor is connected and VRTCcap < 0.5V, the capacitor
must be allowed to charge to 0.5V for oscillator to start.
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Document #: 001-47378 Rev. *D Page 19 of 31
AC Switching Characteristics
Parameters
Description
25 ns 45 ns
Unit
Cypress
Parameters
Alt
Parameters Min Max Min Max
SRAM Read Cycle
tACE tACS Chip Enable Access Time 25 45 ns
tRC [15] tRC Read Cycle Time 25 45 ns
tAA [16] tAA Address Access Time 25 45 ns
tDOE tOE Output Enable to Data Valid 12 20 ns
tOHA[16] tOH Output Hold After Address Change 3 3 ns
tLZCE [12, 17] tLZ Chip Enable to Output Active 3 3 ns
tHZCE [12, 17] tHZ Chip Disable to Output Inactive 10 15 ns
tLZOE [12, 17] tOLZ Output Enable to Output Active 0 0 ns
tHZOE [12, 17] tOHZ Output Disable to Output Inactive 10 15 ns
tPU [12] tPA Chip Enable to Power Active 0 0 ns
tPD [12] tPS Chip Disable to Power Standby 25 45 ns
tDBE - Byte Enable to Data Valid 12 20 ns
tLZBE[12] - Byte Enable to Output Active 0 0 ns
tHZBE[12] - Byte Disable to Output Inactive 10 15 ns
SRAM Write Cycle
tWC tWC Write Cycle Time 25 45 ns
tPWE tWP Write Pulse Width 20 30 ns
tSCE tCW Chip Enable To End of Write 20 30 ns
tSD tDW Data Setup to End of Write 10 15 ns
tHD tDH Data Hold After End of Write 0 0 ns
tAW tAW Address Setup to End of Write 20 30 ns
tSA tAS Address Setup to Start of Write 0 0 ns
tHA tWR Address Hold After End of Write 0 0 ns
tHZWE [12, 17,18] tWZ Write Enable to Output Disable 10 15 ns
tLZWE [12, 17] tOW Output Active after End of Write 3 3 ns
tBW - Byte Enable to End of Write 20 30 ns
Switching Waveforms
Figure 7. SRAM Read Cycle 1: Address Controlled[15, 16, 19]
Address
Data Output
Address Valid
Previous Data Valid Output Data Valid
tRC
tAA
tOHA
Notes
15. WE must be HIGH during SRAM read cycles.
16. Device is continuously selected with CE, OE and BHE / BLE LOW.
17. Measured ±200 mV from steady state output voltage.
18. If WE is LOW when CE goes LOW, the outputs remain in the high impedance state.
19. HSB must remain HIGH during Read and Write cycles.
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Document #: 001-47378 Rev. *D Page 20 of 31
Switching Waveforms
Figure 8. SRAM Read Cycle 2: CE and OE Controlled[3, 15, 19]
Figure 9. SRAM Write Cycle 1: WE Controlled[3, 18, 19, 20]
Address ValidAddress
Data Output Output Data Valid
Standby Active
High Impedance
CE
OE
BHE, BLE
ICC
tHZCE
tRC
tACE
tAA
tLZCE
tDOE
tLZOE
tDBE
tLZBE
tPU tPD
tHZBE
tHZOE
Data Output
Data Input Input Data Valid
High Impedance
Address ValidAddress
Previous Data
tWC
tSCE tHA
tBW
tAW
tPWE
tSA
tSD tHD
tHZWE tLZWE
WE
BHE, BLE
CE
Note
20. CE or WE must be >VIH during address transitions.
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Document #: 001-47378 Rev. *D Page 21 of 31
Switching Waveforms
Figure 10. SRAM Write Cycle 2: CE Controlled[3, 18, 19, 20]
Figure 11. SRAM Write Cycle 3: BHE and BLE Controlled[5, 18, 19, 20, 21]
Data Output
Data Input Input Data Valid
High Impedance
Address Valid
Address
tWC
tSD tHD
BHE, BLE
WE
CE
tSA tSCE tHA
tBW
tPWE
Data Output
Data Input Input Data Valid
High Impedance
Address ValidAddress
tWC
tSD tHD
BHE, BLE
WE
CE
tSCE
tSA tBW tHA
tAW
tPWE
(Not applicable for RTC register writes)
Note
21. Only CE and WE controlled writes to RTC registers are allowed. BLE pin must be held LOW before CE or WE pin goes LOW for writes to RTC register.
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CY14B108K, CY14B108M
Document #: 001-47378 Rev. *D Page 22 of 31
AutoStore/Power Up RECALL
Parameters Description CY14B108K/CY14B108M Unit
Min Max
tHRECALL [22] Power Up RECALL Duration 20 ms
tSTORE [23] STORE Cycle Duration 8 ms
tDELAY [24] Time Allowed to Complete SRAM Write Cycle 25 ns
VSWITCH Low Voltage Trigger Level 2.65 V
tVCCRISE[12] VCC Rise Time 150 μs
VHDIS[12] HSB Output Disable Voltage 1.9 V
tLZHSB[12] HSB To Output Active Time 5 μs
tHHHD[12] HSB High Active Time 500 ns
Switching Waveforms
Figure 12. AutoStore or Power Up RECALL[25]
VSWITCH
VHDIS
VVCCRISE tSTORE tSTORE
tHHHD tHHHD
tDELAY
tDELAY
tLZHSB tLZHSB
tHRECALL
tHRECALL
HSB OUT
AutoStore
POWER-
UP
RECALL
Read & Write
Inhibited
(RWI)
POWER-UP
RECALL
Read & Write BROWN
OUT
AutoStore
POWER-UP
RECALL
Read & Write POWER
DOWN
AutoStore
Note Note
Note
VCC
23 23
26
Notes
22. tHRECALL starts from the time VCC rises above VSWITCH.
23. If an SRAM write has not taken place since the last nonvolatile cycle, no AutoStore or Hardware STORE takes place.
24. On a Hardware Store and AutoStore initiation, SRAM write operation continues to be enabled for time tDELAY
.
25. Read and Write cycles are ignored during STORE, RECALL, and while VCC is below VSWITCH.
26. HSB pin is driven HIGH to VCC only by internal 100 kΩ resistor, HSB driver is disabled.
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CY14B108K, CY14B108M
Document #: 001-47378 Rev. *D Page 23 of 31
Software Controlled STORE and RECALL Cycle
In the following table, the software controlled STORE and RECALL cycle parameters are listed. [27, 28]
Parameters Description 25 ns 45 ns Unit
Min Max Min Max
tRC STORE/RECALL Initiation Cycle Time 25 45 ns
tSA Address Setup Time 0 0 ns
tCW Clock Pulse Width 20 30 ns
tHA Address Hold Time 0 0 ns
tRECALL RECALL Duration 200 200 μs
tSS [29, 30] Soft Sequence Processing Time 100 100 μs
Switching Waveforms
Figure 13. CE and OE Controlled Software STORE and RECALL Cycle[28]
Figure 14. AutoStore Enable and Disable Cycle
tRC tRC
tSA tCW
tCW
tSA
tHA
tLZCE
tHZCE
tHA
tHA
tHA
tSTORE/tRECALL
tHHHD
tLZHSB
High Impedance
Address #1 Address #6Address
CE
OE
HSB(STOREonly)
DQ (DATA)
RWI
tDELAY Note
31
tRC tRC
tSA tCW
tCW
tSA
tHA
tLZCE
tHZCE
tHA
tHA
tHA
tDELAY
Address #1 Address #6Address
CE
OE
DQ (DATA)
tSS
Note
31
Notes
27. The software sequence is clocked with CE controlled or OE controlled reads.
28. The six consecutive addresses must be read in the order listed in Table 2. WE must be HIGH during all six consecutive cycles.
29. This is the amount of time it takes to take action on a soft sequence command. Vcc power must remain HIGH to effectively register command.
30. Commands such as STORE and RECALL lock out I/O until operation is complete which further increases this time. See the specific command.
31. DQ output data at the sixth read may be invalid since the output is disabled at tDELAY time.
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Document #: 001-47378 Rev. *D Page 24 of 31
Hardware STORE Cycle
Parameters Description CY14B108K/CY14B108M Unit
Min Max
tDHSB HSB To Output Active Time when write latch not set 25 ns
tPHSB Hardware STORE Pulse Width 15 ns
Switching Waveforms
Figure 15. Hardware STORE Cycle[23]
Figure 16. Soft Sequence Processing[29, 30]
tPHSB
tPHSB
tDELAY tDHSB
tDELAY
tSTORE
tHHHD
tLZHSB
Write latch set
Write latch not set
HSB (IN)
HSB (OUT)
DQ (Data Out)
RWI
HSB (IN)
HSB (OUT)
RWI
HSB pin is driven high to VCC only by Internal
SRAM is disabled as long as HSB (IN) is driven low
.
HSB driver is disabled
tDHSB
100kOhm resistor,
Address #1 Address #6 Address #1 Address #6
Soft Sequence
Command
tSS tSS
CE
Address
VCC
tSA tCW
Soft Sequence
Command
tCW
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Document #: 001-47378 Rev. *D Page 25 of 31
Truth Table For SRAM Operations
HSB should remain HIGH for SRAM Operations.
For x8 Configuration
CE WE OE Inputs and Outputs[2] Mode Power
H X X High Z Deselect/Power Down Standby
L H L Data Out (DQ0–DQ7); Read Active
L H H High Z Output Disabled Active
L L X Data in (DQ0–DQ7); Write Active
For x16 Configuration
CE WE OE BHE[3] BLE[3] Inputs and Outputs[2] Mode Power
H X X X X High Z Deselect/Power Down Standby
L X X H H High Z Output Disabled Active
L H L L L Data Out (DQ0–DQ15) Read Active
L H L H L Data Out (DQ0–DQ7);
DQ8–DQ15 in High Z
Read Active
L H L L H Data Out (DQ8–DQ15);
DQ0–DQ7 in High Z
Read Active
L H H L L High Z Output Disabled Active
L H H H L High Z Output Disabled Active
L H H L H High Z Output Disabled Active
L L X L L Data In (DQ0–DQ15) Write Active
L L X H L Data In (DQ0–DQ7);
DQ8–DQ15 in High Z
Write Active
L L X L H Data In (DQ8–DQ15);
DQ0–DQ7 in High Z
Write Active
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Document #: 001-47378 Rev. *D Page 26 of 31
Part Numbering Nomenclature
Option:
T - Tape & Reel
Blank - Std.
Speed:
25 - 25 ns
Data Bus:
K - x8 + RTC
M - x16 + RTC
Density:
108 - 8 Mb
Voltage:
B - 3.0V
Cypress
CY14 B 108 K - ZSP 25 X I T
NVSRAM
14 -
Temperature:
I - Industrial (–40 to 85°C)
Pb-Free
Package:
ZSP - 44 TSOP II
45 - 45 ns
ZSP - 54 TSOP II
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Document #: 001-47378 Rev. *D Page 27 of 31
Ordering Information
Speed
(ns) Ordering Code Package
Diagram Package Type Operating
Range
25 CY14B108K-ZS25XIT 51-85087 44-pin TSOPII Industrial
CY14B108K-ZS25XI 51-85187 44-pin TSOPII
CY14B108M-ZSP25XIT 51-85160 54-pin TSOPII
CY14B108M-ZSP25XI 51-85160 54-pin TSOPII
45 CY14B108K-ZS45XIT 51-85087 44-pin TSOPII
CY14B108K-ZS45XI 51-85187 44-pin TSOPII
CY14B108M-ZSP45XIT 51-85160 54-pin TSOPII
CY14B108M-ZSP45XI 51-85160 54-pin TSOPII
All the above parts are Pb-free.
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Document #: 001-47378 Rev. *D Page 28 of 31
Package Diagrams
Figure 17. 44-Pin TSOP II (51-85087)
51-85087 *B
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CY14B108K, CY14B108M
Document #: 001-47378 Rev. *D Page 29 of 31
Figure 18. 54-Pin TSOP II (51-85160)
Package Diagrams (continued)
51-85160 **
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Document #: 001-47378 Rev. *D Page 30 of 31
Document History Page
Document Title: CY14B108K, CY14B108M 8 Mbit (1024K x 8/512K x 16) nvSRAM with Real Time Clock
Document Number: 001-47378
Rev. ECN No. Orig. of
Change
Submission
Date Description of Change
** 2681767 GVCH/PYRS 04/01/09 New Data Sheet
*A 2712462 GVCH/PYRS 05/29/2009 Moved data sheet status from Preliminary to Final
Updated AutoStore operation
Updated C1, C2 values to 12pF, 69pF from 21pF, 21pF respectively
Updated ISB test condition
Updated footnote 10
Updated IBAK and VRTCcap parameter values
Added RBKCHG parameter to RTC characteristics table
Added footnote 14
Referenced footnote 12 to VCCRISE, tHHHD and tLZHSB parameters
Updated VHDIS parameter description
*B 2746310 GVCH 07/29/2009 Page 4: Updated Hardware STORE (HSB) operation description
page 4: Updated Software STORE description
Updated tDELAY parameter description
Updated footnote 24 and added footnote 31
Referenced footnote 31 to Figure 11 and Figure 12
*C 2759948 GVCH 09/04/2009 Removed commercial temperature related specs
Removed 20 ns access speed related specs
Changed VRTCbat max value from 3.3V to 3.6V
Changed RBKCHG min value from 450Ω to 350Ω
Updated footnote 14
*D 2828257 GVCH 12/15/2009 Changed STORE cycles to QuantumTrap from 200K to 1 Million
Updated IBAK RTC backup current spec unit from nA to μA
Added Contents on page 2
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Document #: 001-47378 Rev. *D Revised December 15, 2009 Page 31 of 31
All products and company names mentioned in this document are the trademarks of their respective holders.
CY14B108K, CY14B108M
© Cypress Semiconductor Corporation, 2009. The information contained herein is subject to change without notice. Cypress Semiconductor Corporation assumes no responsibility for the use of any
circuitry other than circuitry embodied in a Cypress product. Nor does it convey or imply any license under patent or other rights. Cypress products are not warranted nor intended to be used for medical,
life support, life saving, critical control or safety applications, unless pursuant to an express written agreement with Cypress. Furthermore, Cypress does not authorize its products for use as critical
components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress products in life-support systems
application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress against all charges.
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and compile the Cypress Source Code and derivative works for the sole purpose of creating custom software and or firmware in support of licensee product to be used only in conjunction with a Cypress
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the express written permission of Cypress.
Disclaimer: CYPRESS MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARD TO THIS MATERIAL, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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