DS1220AB Datasheet, PDF (1/9 Pages) Dallas Semiconductor – 16k Nonvolatile SRAM

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FEATURES
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 24-pin DIP package
Read and write access times as fast as 100 ns
Lithium energy source is electrically
disconnected to retain freshness until power
is applied for the first time
Full ±10% V_CC operating range (DS1220AD)
Optional ±5% V_CC operating range
(DS1220AB)
Optional industrial temperature range of
-40°C to +85°C, designated IND
DS1220AB/AD
16k Nonvolatile SRAM
PIN ASSIGNMENT
A7 ₁
A6 ₂
A5 ₃
A4 ₄
A3 ₅
A2 ₆
A1 ₇
A0 ₈
DQ0 ₉
DQ1 ₁₀
DQ2 11
GND ¹²
24 ^VCC
23
A8
22
A9
21 WE
20
OE
19
A10
18
CE
17
DQ7
16
DQ6
15
DQ5
14 DQ4
13 _DQ3
24-Pin ENCAPSULATED PACKAGE
720-mil EXTENDED
PIN DESCRIPTION
A0-A10
DQ0-DQ7
- Address Inputs
- Data In/Data Out
CE
- Chip Enable
WE
- Write Enable
OE
V_CC
GND
- Output Enable
- Power (+5V)
- Ground
DESCRIPTION
The DS1220AB and DS1220AD 16k Nonvolatile SRAMs are 16,384-bit, fully static, nonvolatile SRAMs
organized as 2048 words by 8 bits. Each NV SRAM has a self-contained lithium energy source and
control circuitry which constantly monitors V_CC 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 SRAMs can be used in place of existing 2k x 8 SRAMs
directly conforming to the popular bytewide 24-pin DIP standard. The devices also match the pinout of
the 2716 EPROM and the 2816 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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