DS1236A Datasheet, PDF (1/20 Pages) Dallas Semiconductor – MicroManager Chip

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DS1236A
MicroManager Chip
FEATURES
Holds microprocessor in check during power
transients
Halts and restarts an out-of-control
microprocessor
Monitors pushbutton for external override
Warns microprocessor of an impending power
failure
Converts CMOS SRAM into nonvolatile
memory
Unconditionally write protects memory when
power supply is out of tolerance
Consumes less than 100 nA of battery current
at 25°C
Controls external power switch for high
current applications
Accurate 10% power supply monitoring
Optional 5% power supply monitoring
designated DS1236A-5
Provides orderly shutdown in nonvolatile
microprocessor applications
Supplies necessary control for low-power
“stop mode” in battery operated hand-held
applications
Standard 16-pin DIP or space-saving 16-pin
SOIC
Optional industrial temperature range -40°C
to +85°C
PIN ASSIGNMENT
VBAT 1 16 RST
VCCO 2 15 RST
VCC 3
GND 4
PF 5
PF 6
WC/SC 7
RC 8
14 PBRST
13 CEI
VBAT
VCCO
12 CEO
VCC
11 ST
10 NMI
GND
PF
PF
9 IN
WC/SC
RC
1 16
2 15
3 14
4 13
5 12
6 11
7 10
8
9
RST
RST
PBRST
CEI
CEO
ST
NMI
IN
16-Pin DIP (300-mil)
See Mech. Drawings Section
16-Pin SOIC (300-mil)
See Mech. Drawings Section
PIN DESCRIPTION
V_BAT
V_CCO
V_CC
GND
- +3-Volt Battery Input
- Switched SRAM Supply Output
- +5-Volt Power Supply Input
- Ground
PF
- Power-Fail (Active High)
PF
- Power-Fail (Active Low)
WC/ SC
- Wake-Up Control (Sleep)
RC
- Reset Control
IN
- Early Warning Input
NMI
- Non-Maskable Interrupt
ST
- Strobe Input
CEO
- Chip Enable Output
CEI
- Chip Enable Input
PBRST
- Pushbutton Reset Input
RST
- Reset Output (Active Low)
RST
- Reset Output (Active High)
DESCRIPTION
The DS1236A MicroManager Chip provides all the necessary functions for power supply monitoring,
reset control, and memory backup in microprocessor-based systems. A precise internal voltage reference
and comparator circuit monitor power supply status. When an out-of-tolerance condition occurs, the
microprocessor reset and power-fail outputs are forced active, and static RAM control unconditionally
write protects external memory. The DS1236A also provides early warning detection of a user-defined
threshold by driving a non-maskable interrupt. External reset control is provided by a pushbutton reset
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