BQ4011 Datasheet, PDF (1/13 Pages) Texas Instruments – 32Kx8 Nonvolatile SRAM

bq4011/bq4011Y
32Kx8 Nonvolatile SRAM
Features
® Data retention in the absence of
power
® Automatic write-protection
during power-up/power-down
cycles
® Industry-standard 28-pin 32K 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 bq4011 is a nonvolatile
262,144-bit static RAM organized as
32,768 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 bq4011 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 bq4011 requires no external cir-
cuitry and is socket-compatible with
industry-standard SRAMs and most
EPROMs and EEPROMs.
Pin Connections
Pin Names
A0 –A14 Address inputs
DQ0–DQ7 Data input/output
CE
Chip enable input
OE
Output enable input
WE
Write enable input
VCC
+5 volt supply input
VSS
Ground
Block Diagram
Selection Guide
Part
Number
Maximum
Access
Time (ns)
bq4011 -100
100
bq4011 -150
150
bq4011 -200
200
Aug. 1993 C
Negative
Supply
Tolerance
-5%
-5%
-5%
Part
Number
bq4011Y-70
bq4011Y -100
bq4011Y -150
bq4011Y -200
1
Maximum
Access
Time (ns)
70
100
150
200
Negative
Supply
Tolerance
-10%
-10%
-10%
-10%