bq4015/Y
512Kx8 Nonvolatile SRAM
is unconditionally write-protected to
prevent an inadvertent write opera-
tion.
- Snap-on power-source for
Features
lithium battery backup
➤ Data retention for at least 10
years without power
- Replaceable power-source
At this time the integral energy
source is switched on to sustain the
memory until after VCC returns
valid.
(part number: bq40MS)
➤ Automatic write-protection during
power-up/power-down cycles
General Description
➤ Conventional SRAM operation,
including unlimited write cycles
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 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.
➤ Internal isolation of battery be-
fore power application
➤ Industry standard 32-pin DIP
pinout
➤ 34-pin LIFETIME LITHIUM™
The bq4015/Y requires no external
circuitry and is compatible with the
industry-standard 4Mb SRAM pin-
out.
module
The control circuitry constantly
monitors the single 5V supply for an
out-of-tolerance condition. When
VCC falls out of tolerance, the SRAM
- Module completely
surface-mounted
Pin Connections
Pin Names
A0–A18
Address inputs
DQ0–DQ7 Data input/output
A
32
1
V
CC
18
A
A
31
30
2
3
4
A
A
WE
16
14
15
17
NC
A15
A16
A18
1
2
34
CE
Chip enable input
Output enable input
Write enable input
No connect
33 A17
A
29
28
27
26
25
24
23
22
21
20
19
18
17
12
3
32 A14
31 A13
30 A12
29 A11
28 A10
27 A9
5
A
A
A
A
A
A
A
13
NC
4
7
6
5
4
3
2
VCC
WE
OE
5
OE
6
7
8
9
10
11
12
13
14
15
16
A
A
9
A
OE
A
CE
DQ
DQ
DQ
DQ
DQ
8
6
7
8
CE
11
WE
NC
VCC
VSS
DQ7
A8
25 A7
9
26
DQ6
DQ5
DQ4
DQ3
DQ2
DQ1
DQ0
VSS
10
11
12
24
23
22
21
20
19
A6
A5
A4
A3
A2
A1
10
A
1
0
0
1
2
13
14
15
16
17
A
DQ
DQ
DQ
7
6
5
4
3
Supply voltage input
Ground
18 A0
V
SS
34-Pin LIFETIME LITHIUM Module
PN4015Yncm.eps
32-Pin DIP Module
PN401501.eps
Selection Guide
Maximum
Access
Time (ns)
Negative
Supply
Tolerance
Maximum
Negative
Supply
Tolerance
Part
Number
Part
Number
Access
Time (ns)
bq4015x -70
bq4015x -85
70
85
-5%
-5%
bq4015Yx -70
bq4015Yx -85
70
85
-10%
-10%
Note: x = MA for PDIP or MS for LIFETIME LITHIUM module.
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