CAT1232LP/CAT1832
5V and 3.3V Supply Monitor, Watchdog Timer,
Manual Reset, with Active High & Low Resets
FEATURES
DESCRIPTION
ꢀ Selectable reset voltage tolerance
— CAT1232LP for 5V supply
— CAT1832 for 3.3V supply
The CAT1232LP and CAT1832 microprocessor
supervisors can halt and restart a “hung-up” or “stalled”
microprocessor, restart a microprocessor after a power
failure, and debounce a manual/push-button micro-
processor reset switch. The devices are drop in
replacements for the Maxim/Dallas Semiconductor
DS1232LP and DS1832 supervisors
ꢀ Selectable watchdog period:
150ms, 600ms or 1.2 sec
ꢀ Two reset outputs
Precision reference and comparator circuits monitor the
5V or 3.3V system power supply voltage, VCC. During
power-up or when the power supply falls outside
selectabletolerancelimits, boththeRESETandRESET
become active. After the power supply voltage rises
above the RESET threshold voltage, the reset signals
remain active for a minimum of 250ms, allowing the
power supply and system processor to stabilize. The
trip-point tolerance input, TOL, selects the trip level
tolerance to be either 5% or 10% for the CAT1232LP 5V
supply and 10% or 20% for the CAT1832 3.3V supply.
— Active high, push-pull reset output
— Active low, open-drain reset output
(CAT1232LP)
— Active low, push-pull reset output (CAT1832)
ꢀ Debounced manual push-button reset
ꢀ Compact SOIC and MSOP packages
APPLICATIONS
ꢀ Microprocessor Systems
ꢀ Portable Equipment
ꢀ Controllers
Each device has a push-pull, active HIGH reset output.
The CAT1232LP also has an open drain, active LOW
reset output while the CAT1832 also has a push-pull,
active LOW reset output.
ꢀ Single Board Computers
ꢀꢀ Instrumentations
A debounced manual reset input activates the reset
outputs and holds them active for a minimum period of
250ms after being released.
ꢀ Telecommunications
Also included is a watchdog timer to reset a
microprocessor that has stopped due to a software or
hardware failure. Three watchdog time-out periods are
selectable: 150ms, 600ms and 1.2sec. If the ST input is
not strobed low before the watchdog time out period
expires, the reset signals become active for a minimum
of 250ms.
For Ordering Information details, see page 11.
FUNCTIONAL DIAGRAM
VCC
(CAT1232LP)
RESET
TOL
Tolerance Selection
Reference
+
VCC
–
40kΩ
RESET
RESET
PBRST
TD
Push Button Debounce
Watchdog Timebase Selection
Watchdog Transition Detector
Reset &
Watchdog Timer
(CAT1832)
ST
© 2006 by Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
Doc. No. 25089, Rev. 0C
1