BQ4010 Datasheet, PDF (1/14 Pages) Texas Instruments – 8Kx8 Nonvolatile SRAM

bq4010/bq4010Y
8Kx8 Nonvolatile SRAM
Features
® Data retention in the absence of
power
® Automatic write-protection
during power-up/power-down
cycles
® Industry-standard 28-pin 8K x 8
pinout
® Conventional SRAM operation;
unlimited write cycles
® 10-year minimum data retention
in absence of power
® Battery internally isolated until
power is applied
General Description
The CMOS bq4010 is a nonvolatile
65,536-bit static RAM organized as
8,192 words by 8 bits. The integral
control circuitry and lithium energy
source provide reliable nonvolatility
coupled with the unlimited write
cycles of standard SRAM.
The control circuitry constantly
monitors the single 5V supply for an
out-of-tolerance condition. When VCC
falls out of tolerance, the SRAM is
unconditionally write-protected to
prevent inadvertent write operation.
At this time the integral energy
source is switched on to sustain the
memory until after VCC returns valid.
The bq4010 uses an extremely low
standby current CMOS SRAM,
coupled with a small lithium coin
cell to provide nonvolatility without
long write-cycle times and the write-
cycle limitations associated with
EEPROM.
The bq4010 requires no external cir-
cuitry and is socket-compatible with
industry-standard SRAMs and most
EPROMs and EEPROMs.
Pin Connections
Pin Names
A0 –A12 Address inputs
DQ0–DQ7 Data input/output
CE
Chip enable input
OE
Output enable input
WE
Write enable input
NC
No connect
VCC
+5 volt supply input
VSS
Ground
Block Diagram
Selection Guide
Part
Number
Maximum
Access
Time (ns)
bq4010 -85
85
bq4010 -150
150
bq4010 -200
200
Negative
Supply
Tolerance
-5%
-5%
-5%
Part
Number
bq4010Y -70
bq4010Y -85
bq4010Y -150
bq4010Y -200
Maximum
Access
Time (ns)
70
85
150
200
Negative
Supply
Tolerance
-10%
-10%
-10%
-10%
Sept. 1996 D
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