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FEATURES
§ 10 years minimum data retention in the
absence of external power
§ Data is automatically protected during power
loss
§ Unlimited write cycles
§ Low-power CMOS operation
§ 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 (DS1265Y)
§ Optional ±5% VCC operating range
(DS1265AB)
§ Optional industrial temperature range of
-40°C to +85°C, designated IND
PIN ASSIGNMENT
PIN DESCRIPTION
A0 - A19 - 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
DESCRIPTION
The DS1265 8M Nonvolatile SRAMs are 8,388,608-bit, fully static nonvolatile SRAMs organized as
1,048,576 words by 8 bits. Each 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. There is no limit on the number of write cycles which can be executed and no
additional support circuitry is required for microprocessor interfacing.
DS1265Y/AB
8M Nonvolatile SRAM
www.maxim-ic.com
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3
4
5
6
7
8
9
10
11
12
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35
36-Pin ENCAPSULATED PACKAGE
740-mil EXTENDED
A18
A14
A7
A6
A5
A4
A3
A2
A0
A1
V
CC
A
19
NC
A
15
A
17
WE
A
13
A
8
A
9
A
11
OE
A
10
DQ7
CE
36
34
33
32
31
30
29
28
27
26
25
23
24
NC
A16
A12
NC
DQ0
DQ1
15
16
22
21
DQ6
DQ5
17
18
GND
DQ2
DQ3
DQ4
19
20
DS1265Y/AB
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READ MODE
The DS1265 devices execute 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 20 address inputs
(A0 - A19) defines which of the 1,048,576 bytes of data is 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 tACC.
WRITE MODE
The DS1265 devices execute a write cycle whenever 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 DS1265AB provides full functional capability for VCC greater than 4.75 volts and write protects by
4.5 volts. The DS1265Y 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 DS1265AB and 4.5 volts for the
DS1265Y.
FRESHNESS SEAL
Each DS1265 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 VTP, the lithium
energy source is enabled for battery backup operation.
DS1265Y/AB
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ABSOLUTE MAXIMUM RATINGS*
Voltage on Any Pin Relative to Ground -0.3V to +7.0V
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 260°C for 10 seconds
* 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
DS1265AB Power Supply Voltage VCC 4.75 5.0 5.25 V
DS1265Y Power Supply Voltage VCC 4.5 5.0 5.5 V
Logic 1 Input Voltage VIH 2.2 VCC V
Logic 0 Input Voltage VIL 0 +0.8 V
DC ELECTRICAL (VCC=5V ± 5% for DS1265AB)
CHARACTERISTICS (tA: See Note 10) (VCC=5V ± 10% for DS1265Y)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Input Leakage Current IIL -2.0 +2.0 mA
I/O Leakage Current IIO -2.0 +2.0 mA
Output Current @ 2.4V IOH -1.0 mA
Output Current @ 0.4V IOL 2.0 mA
Standby Current CE =2.2V ICCS1 1.0 1.5 mA
Standby Current CE =VCC-0.5V ICCS2 100 200 mA
Operating Current ICCO1 85 mA
Write Protection Voltage (DS1265AB) VTP 4.50 4.62 4.75 V
Write Protection Voltage (DS1265Y) VTP 4.25 4.37 4.5 V
CAPACITANCE (tA=25°C)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Input Capacitance CIN 10 20 pF
Output Capacitance CI/O 10 20 pF
DS1265Y/AB
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AC ELECTRICAL (VCC=5V ± 5% for DS1265AB)
CHARACTERISTICS (tA: See Note 10) (VCC=5V ± 10% for DS1265Y)
DS1265AB-70
DS1265Y-70
DS1265AB-100
DS1265Y-100
PARAMETER SYMBOL MIN MAX MIN MAX UNITS NOTES
Read Cycle Time tRC 70 100 ns
Access Time tACC 70 100 ns
OE to Output Valid tOE 35 50 ns
CE to Output Valid tCO 70 100 ns
OE or CE to Output Active tCOE 5 5 ns 5
Output High Z from Deselection tOD 25 35 ns 5
Output Hold from Address Change tOH 55 ns
Write Cycle Time tWC 70 100 ns
Write Pulse Width tWP 55 75 ns 3
Address Setup Time tAW 00 ns
Write Recovery Time tWR1
tWR2
5
15
5
15
ns
ns
12
13
Output High Z from WE tODW 25 35 ns 5
Output Active from WE tOEW 5 5 ns 5
Data Setup Time tDS 30 40 ns 4
Data Hold Time tDH1
tDH2
0
10
0
10
ns
ns
12
13
TIMING DIAGRAM: READ CYCLE
SEE NOTE 1
DS1265Y/AB
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TIMING DIAGRAM: WRITE CYCLE 1
TIMING DIAGRAM: WRITE CYCLE 2
SEE NOTES 2, 3, 4, 6, 7, 8 AND 13
DS1265Y/AB
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POWER-DOWN/POWER-UP CONDITION
SEE NOTE 11
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 ms11
VCC slew from VTP to 0V tF150 ms
VCC slew from 0V to VTP tR150 ms
VCC Valid to CE and WE Inactive tPU 2ms
VCC Valid to End of Write Protection tREC 125 ms
(tA=25°C)
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 or WE . tWP is measured from the latter of CE or WE going
low to the earlier of CE or WE going high.
4. tDS is 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.
DS1265Y/AB
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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 DS1265 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.
10. All AC and DC electrical characteristics are valid over the full operating temperature range. For
commercial products, this range is 0°C to 70°C. For industrial products (IND), this range is -40°C to
+85°C.
11. In a power-down condition the voltage on any pin may not exceed the voltage on VCC.
12. tWR1 and tDH1 are measured from WE going high.
13. tWR2 and tDH2 are measured from CE going high.
14. DS1265 modules are recognized by Underwriters Laboratory (U.L.Ò) under file E99151.
DC TEST CONDITIONS AC TEST CONDITIONS
Outputs Open Output Load: 100 pF + 1TTL Gate
Cycle = 200ns for operating current Input Pulse Levels: 0V to 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
DS1265 TTP - SSS - III
Operating Temperature Range
blank: 0° to 70°
IND: -40° to +85°C
Access Speed
70: 70 ns
100: 100 ns
Package Type
blank: 36-pin 600-mil DIP
VCC Tolerance
AB: ±5%
Y: ±10%
DS1265Y/AB
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DS1265Y/AB NONVOLATILE SRAM 36-PIN 740-MIL EXTENDED MODULE, LONG
PKG 36-PIN
DIM MIN MAX
A IN.
MM
2.080
52.83
2.100
53.34
B IN.
MM
0.720
18.29
0.740
18.80
C IN.
MM
0.355
9.02
0.405
10.29
D IN.
MM
0.180
4.57
0.210
5.33
E IN.
MM
0.015
0.38
0.025
0.63
F IN.
MM
0.120
3.05
0.150
4.06
G IN.
MM
0.090
2.29
0.110
2.79
H IN.
MM
0.590
14.99
0.630
16.00
J IN.
MM
0.008
0.20
0.012
0.30
K IN.
MM
0.015
0.38
0.025
0.58
