TC1232
Microprocessor Monitor
Features
• Precision Voltage Monitor
- Adjustable +4.5V or +4.75V
• Reset Pulse Width – 250 msec minimum
• No External Components
• Adjustable Watchdog Timer
- 150 msec, 600 msec or 1.2 sec
• Operating Voltage 4.0V to 5.5V
• Debounced Manual Reset Input for External
Override
General Description
The TC1232 is a fully-integrated processor supervisor
that provides three important functions to safeguard
processor sanity: precision power on/off reset control,
watchdog timer and external reset override.
On power-up, the TC1232 holds the processor in the
reset state for a minimum of 250 msec after V
CC
is
within tolerance to ensure a stable system start-up.
Microprocessor sanity is monitored by the onboard
watchdog circuit. The microprocessor must provide a
periodic low-going signal on the ST input. Should the
processor fail to supply this signal within the selected
time-out period (150 msec, 600 msec or 1200 msec),
an out-of-control processor is indicated and the
TC1232 issues a processor reset as a result.
The outputs of the TC1232 are immediately driven
active when the PB input is brought low by an external
push button switch or other electronic signal. When
connected to a push button switch, the TC1232
provides contact debounce.
The TC1232 is packaged in a space-saving 8-Pin PDIP
or SOIC package, a 16-Pin SOIC (wide) package and
requires no external components.
ST
Block Diagram
V
CC
Tolerance
Select
(5% or 10%)
+
V
REF
–
Reset
Generator
Watchdog
Timer
+
RST
+
–
RST
TOL
PB RST
Debounce
Watchdog
Timebase
Select
TD
Package Types
8-Pin PDIP
PB RST 1
TD 2
TOL 3
GND 4
8 V
CC
PB RST
TD
TOL
GND
1
2
3
4
7 ST
6 RST
5
RST
8-Pin SOIC
8
V
CC
ST
RST
RST
7
6
5
NC
PB RST
NC
TD
NC
TOL
NC
GND
16-Pin SOIC (Wide)
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
NC
VCC
NC
ST
NC
RST
NC
RST
TC1232
TC1232
TC1232
TC1232
Device Features
RST pin
Device
Type
TC1232
Open-drain
Pull-up Active
Resistor Level
External
Low
RST pin
Type
Push-pull
Minimum
WDI Input
Trip Points
Reset
MR
Typical
Active
(Max)
Active Time
Input
Timeouts (ms)
Level
(ms)
High
4.75V
or 4.5V
250
150, 600 or
1200
Yes
2002-2012 Microchip Technology Inc.
Preliminary
DS21370D-page 1
MICROCHIP [ MICROCHIP TECHNOLOGY ]
