CAT1021, CAT1022, CAT1023
Supervisory Circuits with I
2
C Serial 2k-bit CMOS EEPROM, Manual Reset
and Watchdog Timer
FEATURES
■
Precision power supply voltage monitor
■
Built-in inadvertent write protection
H
GEN
FR
ALO
EE
LE
A
D
F
R
E
E
TM
— 5V, 3.3V and 3V systems
— Five threshold voltage options
■
Watchdog timer
■
Active high or low reset
— WP pin (CAT1021)
■
1,000,000 Program/Erase cycles
■
Manual reset input
■
100 year data retention
■
8-pin DIP, SOIC, TSSOP, MSOP or TDFN
— Valid reset guaranteed at V
CC
= 1 V
■
400kHz I
2
C bus
■
3.0V to 5.5V operation
■
Low power CMOS technology
■
16-Byte page write buffer
(3 x 3 mm foot-print) packages
— TDFN max height is 0.8mm
■
Industrial and extended temperature ranges
DESCRIPTION
The CAT1021, CAT1022 and CAT1023 are complete
memory and supervisory solutions for microcontroller-
based systems. A 2k-bit serial EEPROM memory and a
system power supervisor with brown-out protection are
integrated together in low power CMOS technology.
Memory interface is via a 400kHz I
2
C bus.
The power supply monitor and reset circuit protect memory
and system controllers during power up/down and against
brownout conditions. Five reset threshold voltages support
5V, 3.3V and 3V systems. If power supply voltages are out
of tolerance reset signals become active, preventing the
system microcontroller, ASIC or peripherals from operating.
Reset signals become inactive typically 200 ms after the
The CAT1021 and CAT1023 provide a precision V
CC
supply voltage exceeds the reset threshold level. With both
sense circuit and two open drain outputs: one (RESET) active high and low reset signals, interface to microcontrollers
drives high and the other (RESET) drives low whenever and other ICs is simple. In addition, the
RESET
pin or a
V
CC
falls below the reset threshold voltage. The CAT1022 separate input,
MR,
can be used as an input for push-button
has only a
RESET
output and does not have a Write manual reset capability.
Protect input. The CAT1021 also has a Write Protect
input (WP). Write operations are disabled if WP is The on-chip, 2k-bit EEPROM memory features a 16-byte
connected to a logic high.
page. In addition, hardware data protection is provided by a
V
CC
sense circuit that prevents writes to memory whenever
All supervisors have a 1.6 second watchdog timer circuit V
CC
falls below the reset threshold or until V
CC
reaches the
that resets a system to a known state if software or a reset threshold during power up.
hardware glitch halts or “hangs” the system. For the
CAT1021 and CAT1022, the watchdog timer monitors Available packages include an 8-pin DIP, 8-pin SOIC, 8-pin
the SDA signal. The CAT1023 has a separate watchdog TSSOP, 8-pin TDFN and 8-pin MSOP. The TDFN package
timer interrupt input pin, WDI.
thickness is 0.8mm maximum. TDFN footprint options are
3x3mm.
© 2004 by Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
Doc No. 3009, Rev. K
CATALYST [ CATALYST SEMICONDUCTOR ]
