CAT1021 Datasheet, PDF (1/20 Pages) Catalyst Semiconductor – Supervisory Circuits with I2C Serial 2k-bit CMOS EEPROM, Manual Reset and Watchdog Timer

CAT1021, CAT1022, CAT1023
Supervisory Circuits with I²C Serial 2k-bit CMOS EEPROM, Manual Reset
and Watchdog Timer
FEATURES
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■ Precision power supply voltage monitor
— 5V, 3.3V and 3V systems
— Five threshold voltage options
■ Watchdog timer
■ Active high or low reset
— Valid reset guaranteed at V_CC = 1 V
■ 400kHz I²C bus
■ 3.0V to 5.5V operation
■ Low power CMOS technology
■ 16-Byte page write buffer
■ Built-in inadvertent write protection
— WP pin (CAT1021)
■ 1,000,000 Program/Erase cycles
■ Manual reset input
■ 100 year data retention
■ 8-pin DIP, SOIC, TSSOP, MSOP or TDFN
(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 I²C bus.
The CAT1021 and CAT1023 provide a precision V_CC
sense circuit and two open drain outputs: one (RESET)
drives high and the other (RESET) drives low whenever
V_CC falls below the reset threshold voltage. The CAT1022
has only a RESET output and does not have a Write
Protect input. The CAT1021 also has a Write Protect
input (WP). Write operations are disabled if WP is
connected to a logic high.
All supervisors have a 1.6 second watchdog timer circuit
that resets a system to a known state if software or a
hardware glitch halts or “hangs” the system. For the
CAT1021 and CAT1022, the watchdog timer monitors
the SDA signal. The CAT1023 has a separate watchdog
timer interrupt input pin, WDI.
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
supply voltage exceeds the reset threshold level. With both
active high and low reset signals, interface to microcontrollers
and other ICs is simple. In addition, the RESET pin or a
separate input, MR, can be used as an input for push-button
manual reset capability.
The on-chip, 2k-bit EEPROM memory features a 16-byte
page. In addition, hardware data protection is provided by a
V_CC sense circuit that prevents writes to memory whenever
V_CC falls below the reset threshold or until V_CC reaches the
reset threshold during power up.
Available packages include an 8-pin DIP, 8-pin SOIC, 8-pin
TSSOP, 8-pin TDFN and 8-pin MSOP. The TDFN package
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