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
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.
APPLICATIONS
Microprocessor and Microcontroller based
systems
Intelligent Instruments
Control Systems
Critical µP Monitors
Portable Equipment
PIN CONFIGURATION
TSOT-23 5-Lead
SC-70 5-Lead
RESET
GND
MR
1
2
3
5
VCC
RESET
GND
4
WDI
RESET
1
2
3
5
VCC
PIN FUNCTIONS
Pin Name
¯¯¯¯¯¯
RESET
GND
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
CAT823
CAT824
4
WDI
¯¯¯
MR
RESET
RESET
GND
RESET
1
2
3
5
VCC
CAT825
4
MR
WDI
V
CC
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
1
Doc. No. MD-3027, Rev. B
CATALYST [ CATALYST SEMICONDUCTOR ]
