CAT823, CAT824, CAT825
System Supervisory Voltage Reset with
Watchdog and Manual Reset
FEATURES
n
Automatically restarts microprocessor after
Power failure
n
Monitors pushbutton for external override
n
Accurate under voltage system monitoring
n
Brownout detection system reset for use with
3.0, 3.3, and 5.0 volt systems
n
Pin and function compatible with the
MAX823/24/25 products
n
Operating Range from -40°C to +85°C
n
Available in TSOT-23 5-lead and SC-70 packages
For Ordering Information details, see page 13 & 14.
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
n
Microprocessor and Microcontroller based
systems
n
Intelligent Instruments
n
Control Systems
n
Critical µP Monitors
n
Portable Equipment
PIN CONFIGURATION
TSOT-23 5-Lead
SC-70 5-Lead
RESET
GND
MR
1
2
3
5
V
CC
RESET
GND
4
WDI
RESET
1
2
3
5
V
CC
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
GND
RESET
1
2
3
5
V
CC
RESET
WDI
CAT825
4
MR
V
CC
© 2010 SCILLC. All rights reserved.
Characteristics subject to change without notice
1
Doc. No. MD-3027, Rev. D
ONSEMI [ ON SEMICONDUCTOR ]
