DS1312 Datasheet, PDF (1/11 Pages) Dallas Semiconductor – Nonvolatile Controller with Lithium Battery Monitor

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DS1312
Nonvolatile Controller with Lithium
Battery Monitor
FEATURES
Converts CMOS SRAM into nonvolatile
memory
Unconditionally write-protects SRAM when
V_CC is out of tolerance
Automatically switches to battery backup
supply when V_CC power failure occurs
Monitors voltage of a lithium cell and
provides advanced warning of impending
battery failure
Signals low-battery condition on active low
Battery Warning output signal
Optional -5% or -10% power-fail detection
Space-saving 8-pin DIP and SOIC packages
Optional 16-pin SOIC and 20-pin TSSOP
versions reset processor when power failure
occurs and hold processor in reset during
system power-up
Industrial temperature range of -40°C to
+85°C
PIN ASSIGNMENT
VCCO
1
VBAT
2
TOL 3
GND 4
8
VCCI
7 BW
6 CEO
5 CEI
DS1312 8-Pin DIP
(300-mil)
VCCO
1
VBAT
2
TOL 3
GND 4
8
VCCI
7 BW
6 CEO
5 CEI
DS1312S-2 8-Pin SOIC
(150-mil)
NC 1
VCCO
2
NC 3
VBAT
4
NC 5
TOL 6
NC 7
GND 8
16 NC
15
VCCI
14 RST
13 NC
12 BW
11 CEO
10 NC
9 CEI
DS1312S 16-Pin SOIC
(300-mil)
NC 1
VCCO
2
NC 3
VBAT
4
NC 5
NC 6
TOL 7
NC 8
NC 9
GND 10
20 NC
19
VCCI
18 RST
17 NC
16 NC
15 BW
14 NC
13 CEO
12 NC
11 CEI
DS1312E 20-Pin TSSOP
PIN DESCRIPTION
V_CCI
V_CCO
V_BAT
- +5V Power Supply Input
- SRAM Power Supply Output
- Backup Battery Input
CEI
- Chip Enable Input
CEO
TOL
- Chip Enable Output
- V_CC Tolerance Select
BW
- Battery Warning Output
(Open Drain)
RST
GND
NC
- Reset Output (Open Drain)
- Ground
- No Connection
DESCRIPTION
The DS1312 Nonvolatile Controller with Battery Monitor is a CMOS circuit which solves the application
problem of converting CMOS RAM into nonvolatile memory. Incoming power is monitored for an out-
of-tolerance condition. When such a condition is detected, chip enable is inhibited to accomplish write
protection and the battery is switched on to supply the RAM with uninterrupted power. Special circuitry
uses a low-leakage CMOS process which affords precise voltage detection at extremely low battery
consumption.
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