CAT823 Datasheet, PDF (1/14 Pages) Catalyst Semiconductor – System Supervisory Voltage Reset with Watchdog and Manual Reset

CAT823, CAT824, CAT825
System Supervisory Voltage Reset with
Watchdog and Manual Reset
FEATURES
„ Automatically restarts microprocessor after
Power failure
„ Monitors pushbutton for external override
„ Accurate under voltage system monitoring
„ Brownout detection system reset for use with
3.0, 3.3, and 5.0 volt systems
„ Pin and function compatible with the
MAX823/24/25 products
„ Operating Range from -40°C to +85°C
„ Available in TSOT-23 5-lead and SC-70 packages
For Ordering Information details, see page 13.
APPLICATIONS
„ Microprocessor and Microcontroller based
systems
„ Intelligent Instruments
„ Control Systems
„ Critical µP Monitors
„ Portable Equipment
DESCRIPTION
The CAT823, CAT824, and CAT825 provide basic
reset and monitoring functions for the electronic
systems. Each device monitors the system voltage
and maintains a reset output until that voltage reaches
the device’s specified trip value and then maintains
the reset output active condition until the device’s
internal timer, after a minimum timer of 140ms; to
allow the systems power supply to stabilize.
The CAT823 and CAT824 also have a watchdog input
which can be used to monitor a system signal and
cause a reset to be issued if the signal fails to change
state prior to a timeout condition.
The CAT823 and CAT825 also provide a manual
reset input which can be used to initiate reset if pulled
low. This input can be directly attached to a push-
button or a processor signal.
PIN CONFIGURATION
PIN FUNCTIONS
TSOT-23 5-Lead
SC-70 5-Lead
RESET 1
5 VCC RESET 1
5 VCC
GND 2 CAT823
GND 2 CAT824
MR 3
4 WDI RESET 3
4 WDI
RESET 1
5 VCC
GND 2 CAT825
RESET 3
4 MR
Pin Name
R¯¯E¯S¯E¯T¯
GND
¯M¯R¯
RESET
WDI
V_CC
Function
CMOS Push-Pull Active Low Reset
Output
Ground
Manual Reset input – Pulled high
Internally by a 52kΩ resistor designed
to be driven low by a mechanical
pushbutton, open drain output or CMOS
output.
CMOS Push-Pull Active High Reset
Output
Watchdog Timer Input – Designed to be
driven by a processor output or can be
disabled by tri-stating or leaving open.
Power Supply
© Catalyst Semiconductor, Inc.
1
Characteristics subject to change without notice
Doc. No. MD-3027, Rev. A