October 2006
rev 1.6
ASM1832
3.3V µP Power Supply Monitor and Reset Circuit
Devices are available in 8-pin PDIP, 8-pin SO and compact 8-
pin MicroSO packages.
General Description
The ASM1832 is a fully integrated microprocessor supervisor. It
can halt and restart a “hung-up” microprocessor, restart a
microprocessor after a power failure. It has a watchdog timer
and external reset override. RESET and RESET outputs are
push-pull.
A
precision
temperature-compensated
reference
and
Key Features
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3.3V supply monitor
Push-pull output
Selectable watchdog period
Debounce manual push-button reset input
Precision temperature-compensated voltage reference
and comparator.
Power-up, power-down and brown out detection
250ms minimum reset time
Active LOW and HIGH reset signal
Selectable trip point tolerance: 10% or 20%
Low-cost 8-pin DIP/SO and 8-pin Micro SO packages
Wide operating temperature -40°C to +85°C
comparator circuits monitor the 3.3V, V
CC
input voltage status.
During power-up or when the V
CC
power supply falls outside
selectable tolerance limits, both RESET and RESET become
active. When V
CC
rises above the threshold voltage, the reset
signals remain active for an additional 250ms minimum,
allowing the power supply and system microprocessor to
stabilize. The trip point tolerance signal, TOL, selects the trip
level tolerance to be either 10% or 20%.
A debounced manual reset input, PBRST, activates the reset
outputs for a minimum period of 250ms. There is a watchdog
timer to stop and restart a microprocessor that is “hung-up”.
The watchdog timeouts periods are selectable: 150ms, 610ms,
and 1200ms. If the ST input is not strobed LOW before the
time-out period expires, a reset is generated.
Applications
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Microprocessor systems
Computers
Controllers
Portable instruments
Automotive systems
Typical Operating Circuit
3.3V
Block Diagram
ASM1832
Tolerance Selection
+
V
CC
40KΩ
Reference
V
CC
Push Button
Debounce
Voltage Sense
Comparator
Watchdog
Transition Detector
Reset &
Watchdog Timer
RESET
RESET
V
CC
V
CC
TOL
ASM1832
ST
I/O
µP
-
RESET
GND
TD
TOL
RESET
PBRST
TD
ST
GND
PulseCore Semiconductor Corporation
1715 S, Boscom Ave Suit 200,Campbell, CA 95008. Tel:408-879-9077. Fax:408-879-9018.
www.pulsecoresemi.com
Notice: The information in this document is subject to change without notice
PULSECORE [ PulseCore Semiconductor ]
