19-5603; Rev 10/10
NOT RECOMMENDED FOR NEW DESIGNS
DS1225Y
64k Nonvolatile SRAM
www.maxim-ic.com
FEATURES
PIN ASSIGNMENT
. 10 years minimum data retention in the
absence of external power
VCC
WE
NC
1
28
27
NC
A12
A7
A6
A5
2
3
4
26
25
. Data is automatically protected during power
loss
. Directly replaces 2k x 8 volatile static RAM
or EEPROM
. Unlimited write cycles
. Low-power CMOS
A8
A9
5
6
24
23
A11
OE
A4
A3
A2
7
8
22
21
A10
CE
DQ7
DQ6
A1
A0
9
10
20
19
. JEDEC standard 28-pin DIP package
. Read and write access times of 150 ns
. Full ±10% operating range
. Optional industrial temperature range of
-40°C to +85°C, designated IND
DQ0
11
12
18
17
DQ1
DQ2
GND
DQ5
DQ4
DQ3
13
14
16
15
24-Pin ENCAPSULATED PACKAGE
720-mil EXTENDED
PIN DESCRIPTION
A0-A12
- Address Inputs
DQ0-DQ7
- Data In/Data Out
- Chip Enable
- Write Enable
CE
WE
- Output Enable
- Power (+5V)
- Ground
OE
VCC
GND
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 micro-
processor interfacing.
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