DS1225Y
64k Nonvolatile SRAM
www.maxim-ic.com
FEATURES
PIN ASSIGNMENT
10 years minimum data retention in the
absence of external power
Data is automatically protected during power
loss
Directly replaces 2k x 8 volatile static RAM
or EEPROM
Unlimited write cycles
Low-power CMOS
JEDEC standard 28-pin DIP package
Read and write access times as fast as 150 ns
Full ±10% operating range
Optional industrial temperature range of
-40°C to +85°C, designated IND
28
27
26
25
24
23
22
21
20
19
18
17
VCC
WE
NC
A8
A9
A11
OE
A10
CE
DQ7
DQ6
DQ1
1
2
3
4
5
6
7
8
9
10
11
12
DQ2
13
16
DQ4
GND
14
15
DQ3
NC
A12
A7
A6
A5
A4
A3
A2
A1
A0
DQ0
DQ5
24-Pin ENCAPSULATED PACKAGE
720-mil EXTENDED
PIN DESCRIPTION
A0-A12
DQ0-DQ7
CE
WE
OE
VCC
GND
- Address Inputs
- Data In/Data Out
- Chip Enable
- Write Enable
- Output Enable
- Power (+5V)
- Ground
DESCRIPTION
The DS1225Y 64k Nonvolatile SRAM is a 65,536-bit, fully static, nonvolatile RAM organized as 8192
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. The NV SRAM can be used in place of existing 8k x 8 SRAMs directly conforming to
the popular bytewide 28-pin DIP standard. The DS1225Y also matches the pinout of the 2764 EPROM or
the 2864 EEPROM, allowing direct substitution while enhancing performance. There is no limit on the
number of write cycles that can be executed and no additional support circuitry is required for microprocessor interfacing.
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