BQ4015_07 Datasheet, PDF (1/15 Pages) Texas Instruments – 512Kx8 Nonvolatile SRAM

bq4015/Y
512Kx8 Nonvolatile SRAM
Features
➤ Data retention for at least 10
years without power
➤ Automatic write-protection during
power-up/power-down cycles
➤ Conventional SRAM operation,
including unlimited write cycles
➤ Internal isolation of battery be-
fore power application
➤ Industry standard 32-pin DIP
pinout
➤ 34-pin LIFETIME LITHIUM™
module
- Module completely
surface-mounted
Pin Connections
- Snap-on power-source for
lithium battery backup
- Replaceable power-source
(part number: bq40MS)
General Description
The CMOS bq4015/Y is a nonvola-
tile 4,194,304-bit static RAM organ-
ized as 524,288 words by 8 bits. The
integral control circuitry and lith-
ium energy source provide reliable
nonvolatility coupled with the un-
limited 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 an inadvertent write opera-
tion.
At this time the integral energy
source is switched on to sustain the
memory until after VCC returns
valid.
The bq4015/Y uses extremely low
standby current CMOS SRAMs, cou-
pled with small lithium coin cells to
provide nonvolatility without long
write-cycle times and the write-cycle
limitations associated with EE-
PROM.
The bq4015/Y requires no external
circuitry and is compatible with the
industry-standard 4Mb SRAM pin-
out.
Pin Names
A0–A18 Address inputs
A18 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
VSS 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 DIP Module
PN401501.eps
NC 1
A15 2
A16 3
NC 4
V_{CC 5}
WE 6
OE 7
CE 8
DQ₇ 9
DQ₆ 10
DQ₅ 11
DQ₄ 12
DQ₃ 13
DQ2 14
DQ₁ 15
DQ₀ 16
VSS 17
34 A18
33 A17
32 A14
31 A13
30 A12
29 A11
28 A10
27 A9
26 A8
25 A7
24 A6
23 A5
22 A4
21 A3
20 A2
19 A1
18 A0
34-Pin LIFETIME LITHIUM Module
PN4015Yncm.eps
DQ0–DQ7 Data input/output
CE
Chip enable input
OE
Output enable input
WE
Write enable input
NC
No connect
VCC
Supply voltage input
VSS
Ground
Selection Guide
Part
Number
bq4015x -70
bq4015x -85
Maximum
Access
Time (ns)
70
85
Negative
Supply
Tolerance
-5%
-5%
Part
Number
bq4015Yx -70
bq4015Yx -85
Note: x = MA for PDIP or MS for LIFETIME LITHIUM module.
Maximum
Access
Time (ns)
70
85
Negative
Supply
Tolerance
-10%
-10%
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