SUMMIT
MICROELECTRONICS, Inc.
SMS1242
2.5V, 3V, 3.3V & 5V Dual Voltage, Dual Reset
Microprocessor Supervisory Circuits
FEATURES
• Supply voltage monitor
- Nominal V
RST
of 2.45V, 2.65V, 2.95V, 4.45V,
4.55V or 4.65V
- RESET# Outputs Guaranteed true at V
CC
= 1V
- 150ms Reset Delay Time
• Second voltage monitor
- V
SENSE
Input
- 1.25V threshold ±1%
• Manual Reset Input
• Includes 16k-bits nonvolatile memory
- Industry standard 2-wire serial interface
OVERVIEW
The SMS1242 microprocessor supervisory circuit re-
duces the complexity and number of components required
to monitor the supply voltage in +5V, +3V and +2.5V
systems. The SMS1242 will significantly improve system
reliability and accuracy when compared to implementing
the same functions with discrete components.
The SMS1242 provides reset output during power-up,
power-down, and brown-out conditions. It has a 1.25V
threshold input detector for power-fail warning, low battery
detection, or monitoring a secondary power supply. The
part also integrates a separate active low manual reset
input.
It also has 16k-bits of nonvolatile memory accessible over
an industry standard 2-wire serial interface.
FUNCTIONAL BLOCK DIAGRAM
VCC
8
SCL
SDA
6
5
NONVOLATILE
MEMORY
ARRAY
VSENSE 3
+
–
7 MR#
2 RESET1#
+
–
VTRIP
RESET
GENERATOR
1
RESET2#
1.25V
4
GND
2038 BD 2.0
© SUMMIT MICROELECTRONICS, Inc. 2000 • 300 Orchard City Drive, Suite 131 • Campbell, CA 95008 • Phone 408-378-6461 • Fax 408-378-6586 • www.summitmicro.com
2038 2.0 6/8/00
Characteristics subject to change without notice
1
SUMMIT [ SUMMIT MICROELECTRONICS, INC. ]
