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