DS1249W Datasheet, PDF (1/8 Pages) Dallas Semiconductor – 3.3V 2048kb Nonvolatile SRAM

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DS1249W
3.3V 2048kb Nonvolatile SRAM
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 100ns
§ Lithium energy source is electrically
disconnected to retain freshness until power is
applied for the first time
§ Optional industrial (IND) temperature range
of -40°C to +85°C
§ JEDEC standard 32-pin DIP package
PIN ASSIGNMENT
NC 1
A16 ₂
A14 3
A12 4
A7 5
A6 6
A5 7
A4 8
A3 9
A2 10
A1 11
A0 ¹²
DQ0 ¹³
DQ1 14
DQ2 15
GND 16
32
VCC
31 A15
30 A17
29 WE
28 A13
27 A8
26 A9
25 A11
24 OE
23 A10
22
CE
21 DQ7
20 DQ6
19 DQ5
18 DQ4
17 DQ3
32-Pin Encapsulated Package
740mil Extended
PIN DESCRIPTION
A0–A17
- Address Inputs
DQ0–DQ7
- Data In/Data Out
CE
- Chip Enable
WE
- Write Enable
OE
- Output Enable
V_CC
GND
- Power (+3.3V)
- Ground
NC
- No Connect
DESCRIPTION
The DS1249W 2048kb nonvolatile (NV) SRAMs are 2,097,152-bit, fully static, NV SRAMs organized as
262,144 words by 8 bits. Each NV SRAM has a self-contained lithium energy source and control circuitry
that 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. 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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