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DS1245Y/AB
1024k Nonvolatile SRAM
www.maxim-ic.com
FEATURES
10 years minimum data retention in the
absence of external power
Data is automatically protected during power
loss
Replaces 128k x 8 volatile static RAM,
EEPROM or Flash memory
Unlimited write cycles
Low-power CMOS
Read and write access times as fast as 70 ns
Lithium energy source is electrically
disconnected to retain freshness until power is
applied for the first time
Full 10% VCC operating range (DS1245Y)
Optional 5% VCC operating range
(DS1245AB)
Optional industrial temperature range of
-40C to +85C, designated IND
JEDEC standard 32-pin DIP package
PowerCap Module (PCM) package
- Directly surface-mountable module
- Replaceable snap-on PowerCap provides
lithium backup battery
- Standardized pinout for all nonvolatile
SRAM products
- Detachment feature on PowerCap allows
easy removal using a regular screwdriver
PIN ASSIGNMENT
PIN DESCRIPTION
A0 - A16 - Address Inputs
DQ0 - DQ7 - Data In/Data Out
CE - Chip Enable
WE - Write Enable
OE - Output Enable
VCC - Power (+5V)
GND - Ground
NC - No Connect
13
1
2
3
4
5
6
7
8
9
10
11
12
14
31
32-PIN ENCAPSULATED PACKAGE
740 MIL EXTENDED
A14
A7
A5
A4
A3
A2
A1
A0
DQ1
DQ0
V
CC
A15
NC
WE
A13
A8
A9
A11
OE
A10
CE
DQ7
DQ5
DQ6
32
30
29
28
27
26
25
24
23
22
21
19
20
A16
NC
A12
A6
DQ2 15
16
18 DQ4
17 DQ3
GND
1
NC 2
3
A15
A16
NC
VCC
WE
OE
CE
DQ7
DQ6
DQ5
DQ4
DQ3
DQ2
DQ1
DQ0
GND
4
5
6
7
8
9
10
11
12
13
14
15
16
17
NC
NC
33
34
A14
32
31 A13
30 A12
29
28
27
26
25
24
23
22
21
20
19
18
A11
A10
A9
A8
A7
A6
A5
A4
GND VBAT A3
A2
A1
A0
34-PIN POWERCAP MODULE (PCM)
(USES DS9034PC POWERCAP)
DS1245Y/AB
DESCRIPTION
The DS1245 1024k Nonvolatile SRAMs are1,048,576-bit, fully static, nonvolatile SRAMs organized as
131,072 words by 8 bits. Each complete NV SRAM has a self-contained lithium energy source and
control circuitry which constantly monitors VCC for an out-of-tolerance condition. When such a condition
occurs, the lithium energy source is automatically switched on and write protection is unconditionally
enabled to prevent data corruption. DIP-package DS1245 devices can be used in place of existing 128k x
8 static RAMs directly conforming to the popular bytewide 32-pin DIP standard. DS1245 devices in the
PowerCap Module package are directly surface mountable and are normally paired with a DS9034PC
PowerCap to form a complete Nonvolatile SRAM module. There is no limit on the number of write
cycles that can be executed and no additional support circuitry is required for microprocessor interfacing.
READ MODE
The DS1245 executes a read cycle whenever WE (Write Enable) is inactive (high) and CE (Chip Enable)
and OE (Output Enable) are active (low). The unique address specified by the 17 address inputs (A0 -
A16) defines which of the 131,072 bytes of data is to be accessed. Valid data will be available to the eight
data output drivers within tACC (Access Time) after the last address input signal is stable, providing that
CE and OE (Output Enable) access times are also satisfied. If OE and CE access times are not satisfied,
then data access must be measured from the later occurring signal (CE or OE ) and the limiting parameter
is either tCO for CE or tOE for OE rather than address access.
WRITE MODE
The DS1245 executes a write cycle whenever the WE and CE signals are active (low) after address
inputs are stable. The later occurring falling edge of CE or WE will determine the start of the write cycle.
The write cycle is terminated by the earlier rising edge of CE or WE . All address inputs must be kept
valid throughout the write cycle. WE must return to the high state for a minimum recovery time (tWR)
before another cycle can be initiated. The OE control signal should be kept inactive (high) during write
cycles to avoid bus contention. However, if the output drivers are enabled (CE and OE active) then WE
will disable the outputs in tODW from its falling edge.
DATA RETENTION MODE
The DS1245AB provides full functional capability for VCC greater than 4.75 volts and write protects by
4.5 volts. The DS1245Y provides full functional capability for VCC greater than 4.5 volts and write-
protects by 4.25 volts. Data is maintained in the absence of VCC without any additional support circuitry.
The nonvolatile static RAMs constantly monitor VCC. Should the supply voltage decay, the NV SRAMs
automatically write-protect themselves, all inputs become “don’t care,” and all outputs become high
impedance. As VCC falls below approximately 3.0 volts, a power switching circuit connects the lithium
energy source to RAM to retain data. During power-up, when VCC rises above approximately 3.0 volts,
the power switching circuit connects external VCC to RAM and disconnects the lithium energy source.
Normal RAM operation can resume after VCC exceeds 4.75 volts for the DS1245AB and 4.5 volts for the
DS1245Y.
FRESHNESS SEAL
Each DS1245 device is shipped from Dallas Semiconductor with its lithium energy source disconnected,
guaranteeing full energy capacity. When VCC is first applied at a level greater than 4.25 volts, the lithium
energy source is enabled for battery back-up operation.
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DS1245Y/AB
PACKAGES
The DS1245 devices are available in two packages: 32-pin DIP and 34-pin PowerCap Module (PCM).
The 32-pin DIP integrates a lithium battery, an SRAM memory and a nonvolatile control function into a
single package with a JEDEC-standard 600-mil DIP pinout. The 34-pin PowerCap Module integrates
SRAM memory and nonvolatile control along with contacts for connection to the lithium battery in the
DS9034PC PowerCap. The PowerCap Module package design allows a DS1245 PCM device to be
surface mounted without subjecting its lithium backup battery to destructive high-temperature reflow
soldering. After a DS1245 PCM is reflow soldered, a DS9034PC PowerCap is snapped on top of the
PCM to form a complete Nonvolatile SRAM module. The DS9034PC is keyed to prevent improper
attachment. DS1245 PowerCap Modules and DS9034PC PowerCaps are ordered separately and shipped
in separate containers. See the DS9034PC data sheet for further information.
ABSOLUTE MAXIMUM RATINGS*
Voltage on Any Pin Relative to Ground -0.3V to +6.0V
Operating Temperature 0°C to 70°C, -40°C to +85°C for Ind parts
Storage Temperature -40°C to +70°C, -40°C to +85°C for Ind parts
Soldering Temperature
DIP Module +260°C for 10 seconds
Caution: Do Not Reflow (Wave or Hand Solder Only)
PowerCap
Module See IPC/JEDEC J-STD-020
* This is a stress rating only and functional operation of the device at these or any other conditions
above those indicated in the operation sections of this specification is not implied. Exposure to
absolute maximum rating conditions for extended periods of time may affect reliability.
RECOMMENDED DC OPERATING CONDITIONS (tA: See Note 10)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
DS1245AB Power Supply Voltage VCC 4.75 5.0 5.25 V
DS1245Y Power Supply Voltage VCC 4.5 5.0 5.5 V
Logic 1 VIH 2.2 VCC V
Logic 0 VIL 0.0 0.8 V
DC ELECTRICAL (VCC=5V 5% for DS1245AB)
CHARACTERISTICS (tA: See Note 10) (VCC=5V 10% for DS1245Y)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Input Leakage Current IIL -1.0 +1.0 A
I/O Leakage Current CE VIH VCC IIO -1.0 +1.0 A
Output Current @ 2.4V IOH -1.0 mA
Output Current @ 0.4V IOL 2.0 mA
Standby Current CE =2.2V ICCS1 200 600 A
Standby Current CE =VCC-0.5V ICCS2 50 150 A
Operating Current ICCO1 85 mA
Write Protection Voltage (DS1245AB) VTP 4.50 4.62 4.75 V
Write Protection Voltage (DS1245Y) VTP 4.25 4.37 4.5 V
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DS1245Y/AB
CAPACITANCE (tA=25C)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Input Capacitance CIN 5 10 pF
Input/Output Capacitance CI/O 5 10 pF
AC ELECTRICAL (VCC=5V 5% for DS1245AB)
CHARACTERISTICS (tA: See Note 10) (VCC=5V 10% for DS1245Y)
DS1245AB-70
DS1245Y-70 DS1245AB-85
DS1245Y-85
PARAMETER SYMBOL MIN MAX MIN MAX UNITS NOTES
Read Cycle Time tRC 70 85 ns
Access Time tACC 70 85 ns
OE to Output Valid tOE 35 45 ns
CE to Output Valid tCO 70 85 ns
OE or CE to Output Active tCOE 5 5 ns 5
Output High Z from Deselection tOD 25 30 ns 5
Output Hold from Address Change tOH 5 5 ns
Write Cycle Time tWC 70 85 ns
Write Pulse Width tWP 55 65 ns 3
Address Setup Time tAW 0 0 ns
Write Recovery Time tWR1
tWR2
5
15 5
15 ns
ns 12
13
Output High Z from WE tODW 25 30 ns 5
Output Active from WE tOEW 5 5 ns 5
Data Setup Time tDS 30 35 ns 4
Data Hold Time tDH1
tDH2
0
10 0
10 ns
ns 12
13
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DS1245Y/AB
AC ELECTRICAL (VCC=5V 5% for DS1245AB)
CHARACTERISTICS (tA: See Note 10) (VCC=5V 10% for DS1245Y)
DS1245AB-100
DS1245Y-100 DS1245AB-120
DS1245Y-120
PARAMETER SYMBOL MIN MAX MIN MAX UNITS NOTES
Read Cycle Time tRC 100 120 ns
Access Time tACC 100 120 ns
OE to Output Valid tOE 50 60 ns
CE to Output Valid tCO 100 120 ns
OE or CE to Output Active tCOE 5 5 ns 5
Output High Z from Deselection tOD 35 35 ns 5
Output Hold from Address Change tOH 5 5 ns
Write Cycle Time tWC 100 120 ns
Write Pulse Width tWP 75 90 ns 3
Address Setup Time tAW 0 0 ns
Write Recovery Time tWR1
tWR2
5
15 5
15 ns
ns 12
13
Output High Z from WE tODW 35 35 ns 5
Output Active from WE tOEW 5 5 ns 5
Data Setup Time tDS 40 50 ns 4
Data Hold Time tDH1
tDH2
0
10 0
10 ns
ns 12
13
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DS1245Y/AB
READ CYCLE
SEE NOTE 1
WRITE CYCLE 1
SEE NOTES 2, 3, 4, 6, 7, 8, and 12
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DS1245Y/AB
WRITE CYCLE 2
SEE NOTES 2, 3, 4, 6, 7, 8, and 13
POWER-DOWN/POWER-UP CONDITION
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DS1245Y/AB
POWER-DOWN/POWER-UP TIMING (tA: See Note 10)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
VCC Fail Detect to CE and WE Inactive tPD 1.5
s 11
VCC slew from VTP to 0V tF 150 s
VCC slew from 0V to VTP t
R 150 s
VCC Valid to CE and WE Inactive tPU 2 ms
VCC Valid to End of Write Protection tREC 125 ms
(tA=25C)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Expected Data Retention Time tDR 10 years 9
WARNING:
Under no circumstance are negative undershoots, of any amplitude, allowed when device is in battery
backup mode.
NOTES:
1. WE is high for a Read Cycle.
2. OE = VIH or VIL. If OE = VIH during write cycle, the output buffers remain in a high impedance state.
3. tWP is specified as the logical AND of CE and WE . tWP is measured from the latter of CE or WE
going low to the earlier of CE or WE going high.
4. tDH, tDS are measured from the earlier of CE or WE going high.
5. These parameters are sampled with a 5 pF load and are not 100% tested.
6. If the CE low transition occurs simultaneously with or latter than the WE low transition, the output
buffers remain in a high impedance state during this period.
7. If the CE high transition occurs prior to or simultaneously with the WE high transition, the output
buffers remain in high impedance state during this period.
8. If WE is low or the WE low transition occurs prior to or simultaneously with the CE low transition,
the output buffers remain in a high impedance state during this period.
9. Each DS1245 has a built-in switch that disconnects the lithium source until the user first applies VCC.
The expected tDR is defined as accumulative time in the absence of VCC starting from the time power
is first applied by the user. This parameter is assured by component selection, process control, and
design. It is not measured directly during production testing.
10. Each DS1245 has a built-in switch that disconnects the lithium source until VCC is first applied by the
user. The expected tDR is defined as accumulative time in the absence of VCC starting from the time
power is first applied by the user.
11. All AC and DC electrical characteristics are valid over the full operating temperature range. For
commercial products, this range is 0C to 70C. For industrial products (IND), this range is -40C to
+85C.
12. In a power-down condition the voltage on any pin may not exceed the voltage on VCC.
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DS1245Y/AB
13. tWR1 and tDH1 are measured from WE going high.
14. tWR2 and tDH2 are measured from CE going high.
15. DS1245 modules are recognized by Underwriters Laboratory (U.L.) under file E99151.
DC TEST CONDITIONS AC TEST CONDITIONS
Outputs Open Output Load: 100 pF + 1TTL Gate
Cycle = 200 ns for operating current Input Pulse Levels: 0 - 3.0V
All voltages are referenced to ground Timing Measurement Reference Levels
Input: 1.5V
Output: 1.5V
Input pulse Rise and Fall Times: 5 ns
ORDERING INFORMATION
Part Number Temperature Range Supply
Tolerance Pin/Package Speed Grade
DS1245AB-70 0°C to +70°C
5V 5% 32 / 740 EMOD 70ns
DS1245AB-70+ 0°C to +70°C
5V 5% 32 / 740 EMOD 70ns
DS1245ABP-70 0°C to +70°C
5V 5% 34 / PowerCap* 70ns
DS1245ABP-70+ 0°C to +70°C
5V 5% 34 / PowerCap* 70ns
DS1245AB-70IND -40°C to +85°C
5V 5% 32 / 740 EMOD 70ns
DS1245AB-70IND+ -40°C to +85°C
5V 5% 32 / 740 EMOD 70ns
DS1245ABP-70IND -40°C to +85°C
5V 5% 34 / PowerCap* 70ns
DS1245ABP-70IND+ -40°C to +85°C
5V 5% 34 / PowerCap* 70ns
DS1245AB-85 0°C to +70°C
5V 5% 32 / 740 EMOD 85ns
DS1245AB-85+ 0°C to +70°C
5V 5% 32 / 740 EMOD 85ns
DS1245AB-100 0°C to +70°C
5V 5% 32 / 740 EMOD 100ns
DS1245AB-100+ 0°C to +70°C
5V 5% 32 / 740 EMOD 100ns
DS1245ABP-100 0°C to +70°C
5V 5% 34 / PowerCap* 100ns
DS1245ABP-100+ 0°C to +70°C
5V 5% 34 / PowerCap* 100ns
DS1245AB-120 0°C to +70°C
5V 5% 32 / 740 EMOD 120ns
DS1245AB-120+ 0°C to +70°C
5V 5% 32 / 740 EMOD 120ns
DS1245AB-120IND -40°C to +85°C
5V 5% 32 / 740 EMOD 120ns
DS1245AB-120IND+ -40°C to +85°C
5V 5% 32 / 740 EMOD 120ns
DS1245Y-70 0°C to +70°C
5V 10% 32 / 740 EMOD 70ns
DS1245Y-70+ 0°C to +70°C
5V 10% 32 / 740 EMOD 70ns
DS1245YP-70 0°C to +70°C
5V 10% 34 / PowerCap* 70ns
DS1245YP-70+ 0°C to +70°C
5V 10% 34 / PowerCap* 70ns
DS1245Y-70IND -40°C to +85°C
5V 10% 32 / 740 EMOD 70ns
DS1245Y-70IND+ -40°C to +85°C
5V 10% 32 / 740 EMOD 70ns
DS1245YP-70IND -40°C to +85°C
5V 10% 34 / PowerCap* 70ns
DS1245YP-70IND+ -40°C to +85°C
5V 10% 34 / PowerCap* 70ns
DS1245Y-85 0°C to +70°C
5V 10% 32 / 740 EMOD 85ns
DS1245Y-85+ 0°C to +70°C
5V 10% 32 / 740 EMOD 85ns
DS1245Y-100 0°C to +70°C
5V 10% 32 / 740 EMOD 100ns
DS1245Y-100+ 0°C to +70°C
5V 10% 32 / 740 EMOD 100ns
DS1245YP-100 0°C to +70°C
5V 10% 34 / PowerCap* 100ns
DS1245YP-100+ 0°C to +70°C
5V 10% 34 / PowerCap* 100ns
DS1245Y-120 0°C to +70°C
5V 10% 32 / 740 EMOD 120ns
DS1245Y-120+ 0°C to +70°C
5V 10% 32 / 740 EMOD 120ns
DS1245Y-120IND -40°C to +85°C
5V 10% 32 / 740 EMOD 120ns
DS1245Y-120IND+ -40°C to +85°C
5V 10% 32 / 740 EMOD 120ns
+ Denotes lead(Pb)-free/RoHS-compliant product.
* DS9034PC or DS9034PCI (PowerCap) required. Must be ordered separately.
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DS1245Y/AB NONVOLATILE SRAM, 34-PIN POWERCAP MODULE
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INCHES
PKG
DIM MIN NOM MAX
A 0.920 0.925 0.930
B 0.980 0.985 0.990
C - - 0.080
D 0.052 0.055 0.058
E 0.048 0.050 0.052
F 0.015 0.020 0.025
G 0.020 0.025 0.030
DS1245Y/AB
DS1245Y/AB NONVOLATILE SRAM, 34-PIN POWERCAP MODULE WITH
POWERCAP
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INCHES
PKG
DIM MIN NOM MAX
A 0.920 0.925 0.930
B 0.955 0.960 0.965
C 0.240 0.245 0.250
D 0.052 0.055 0.058
E 0.048 0.050 0.052
F 0.015 0.020 0.025
G 0.020 0.025 0.030
ASSEMBLY AND USE
Reflow soldering
Dallas Semiconductor recommends that PowerCap Module bases experience one pass through solder
reflow oriented label-side up (live-bug).
Hand soldering and touch-up
Do not touch soldering iron to leads for more than 3 seconds. To solder, apply flux to the pad, heat the
lead frame pad and apply solder. To remove part, apply flux, heat pad until solder reflows, and use a
solder wick.
LPM replacement in a socket
To replace a Low Profile Module in a 68-pin PLCC socket, attach a DS9034PC PowerCap to a module
base then insert the complete module into the socket one row of leads at a time, pushing only on the
corners of the cap. Never apply force to the center of the device. To remove from a socket, use a PLCC
extraction tool and ensure that it does not hit or damage any of the module IC components. Do not use
any other tool for extraction.
DS1245Y/AB
RECOMMENDED POWERCAP MODULE LAND PATTERN
INCHES
PKG
DIM MIN NOM MAX
A - 1.050 -
B - 0.826 -
C - 0.050 -
D - 0.030 -
E - 0.112 -
RECOMMENDED POWERCAP MODULE SOLDER STENCIL
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INCHES
PKG
DIM MIN NOM MAX
A - 1.050 -
B - 0.890 -
C - 0.050 -
D - 0.030 -
E - 0.080 -
PACKAGE INFORMATION
For the latest package outline info rmation and land patterns, go to http://www.maxim-ic.com/packages.
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
32 MOD MDT32-6 21-0245
34 PWRCP PC2+3 21-0246
DS1245Y/AB
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REVISION HISTORY
REVISION
DATE DESCRIPTION PAGES CHANGED
121907
Added package information table.
Removed the DIP module package drawing and
dimension table.
10, 11, 12
