IMP1 832
P
OWER
M
ANAGEMENT
3.3V µP Power Supply
Monitor and Reset Circuit
Key Features
x
Pin compatible with the Dallas Semiconductor
DS1832
— Over 40% lower supply current
x
3.3V supply monitor
x
Push-pull output
x
Selectable watchdog period
x
Debounce manual push-button reset input
x
Precision temperature-compensated voltage
reference and comparator
x
Power-up, power-down and brownout detection
x
250ms minimum reset time
x
Active LOW and HIGH reset signal
x
Selectable trip point tolerance: 10% or 20%
x
Low-cost 8-pin DIP/SO and 8-pin MicroSO
packages
x
Wide operating temperature – 40°C to +85°C
– Selectable Trip -Point Tolerance and
Watchdog Period
– Push-Button Reset
– Push-Pull Reset Outputs
The IMP1832 microprocessor supervisor can halt and restart a “hung-
up” or “stalled” microprocessor, restart a microprocessor after a power
failure, and debounce a manual push-button microprocessor reset
switch. The IMP1832 features over 40% lower supply current than the
pin compatible Dallas Semiconductor DS1832.
Precision temperature compensated reference and comparator circuits
monitor the 3.3V, V
CC
input voltage. 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 Also included is a watchdog timer to stop and restart a
tolerance signal, TOL, selects the trip level tolerance to be either 10- or microprocessor that is “hung-up”. Three watchdog time-
20-percent.
out periods are selectable: 150ms, 610ms and 1,200ms. If the
ST input is not strobed LOW before the time-out period
RESET and RESET outputs are push-pull.
expires, a reset is issued.
A debounced manual reset input, PBRST, activates the reset outputs for
Devices are available in 8-pin DIP, 8-pin SO and compact
a minimum period of 250ms.
8-pin MicroSO packages.
Block Diagram
V
CC
8
IMP1832
10%/20% Tolerance
Selection
V
CC
TOL
3
6
RESET
+
V
CC
V
CC
40k
9
PBRST
1
Push Button
Debounce
Watchdog
Timebase Selection
Watchdog
Transition Detector
4
1832_02.eps
Reference
–
5
RESET
TD
2
Reset &
Watchdog Timer
ST
7
GND
©
1999 IMP, Inc.
408-432-9100/www.impweb.com
1
IMP [ IMP, INC ]
