Preliminary Information
CAT1026, CAT1027
Dual Voltage Supervisory Circuits with I2C Serial 2K CMOS EEPROM
FEATURES
■ Precision VCC power supply voltage monitor
— 5V, 3.3V and 3V systems
■ 16-Byte page write buffer
■ Built-in inadvertent write protection
■ 1,000,000 Program/Erase cycles
■ Manual reset capability
— Five threshold voltage options
■ Additional voltage monitoring
— Externally adjustable down to 1.25V
■ 100 year data retention
■ Watchdog timer (CAT1027 only)
■ Active high or low reset
— Valid reset guaranteed to VCC=1V
■ 400kHz I2C bus
■ 8-pin DIP, SOIC, TSSOP, TDFN (MSOP
(3x4.9mm) & 3x3mm foot prints) or MSOP
packages
— TDFN max height is 0.8mm
■ Automotive, extended automotive and
■ 2.7V to 5.5V operation
industrial temperature ranges
■ Low power CMOS technology
DESCRIPTION
The CAT1026 and CAT1027 are complete memory and used as an input for push-button manual reset capability.
supervisorysolutionsformicrocontroller-basedsystems.
The CAT1026 and CAT1027 provide an auxiliary voltage
A 2kbit serial EEPROM memory and a system power
sensor input, VSENSE, which is used to monitor a second
supervisor with brown-out protection are integrated
system supply. The auxiliary high impedance comparator
together in low power CMOS technology. Memory
drives the open drain output, VLOW, whenever the sense
interface is via a 400kHz I2C bus.
voltage is below 1.25V threshold.
The CAT1026 and CAT1027 provide a precision VCC
TheCAT1027isdesignedwitha1.6secondwatchdogtimer
sense circuit with five reset threshold voltage options
circuit that resets a system to a known state if software or a
that support 5V, 3.3V and 3V systems. The power
hardware glitch halts or “hangs” the system. The CAT1027
supply monitor and reset circuit protects memory and
features a watchdog timer interrupt input, WDI.
systems controllers during power up/down and against
brownout conditions. If power supply voltages are out of
EEPROM memory features a 16-byte page. In addition,
tolerance reset signals become active preventing the
hardware data protection is provided by a VCC sense circuit
system microcontroller, ASIC, or peripherals from
that prevents writes to memory whenever VCC falls below
the reset threshold or until VCC reaches the reset threshold
operating.
during power up.
The CAT1026 features two open drain reset outputs:
one (RESET) drives high and the other (RESET) drives
low whenever VCC falls below the threshold. Reset
Available packages include 8-pin DIP and surface mount,
8-pin SO, 8-pin TSSOP, 8-pin TDFN and 8-pin MSOP
outputs become inactive typically 200 ms after the
packages. The TDFN package thickness is 0.8mm
supply voltage exceeds the reset threshold value. With
maximum. TDFN footprint options are 3x3mm or 3x4.9mm
both active high and low reset signals, interface to
(MSOP pad layout).
microcontrollers and other ICs is simple. CAT1027 has
onlyaRESET output. Inaddition, the RESET pincanbe
© 2003 by Catalyst Semiconductor, Inc.
Doc No. 3010, Rev. E
Characteristics subject to change without notice
CATALYST [ CATALYST SEMICONDUCTOR ]
