CAT1026, CAT1027
Dual Voltage Supervisory Circuits with
2
I C Serial 2k-bit CMOS EEPROM
FEATURES
Precision V
CC
Power Supply Voltage Monitor
—
5V, 3.3V and 3V systems
—
Five threshold voltage options
Additional voltage monitoring
—
Externally adjustable down to 1.25V
Watchdog timer (CAT1027 only)
Active High or Low Reset
—
Valid reset guaranteed at V
CC
= 1V
400kHz I
2
C Bus
2.7V to 5.5V Operation
Low power CMOS technology
16-Byte Page Write Buffer
Built-in inadvertent write protection
1,000,000 Program/Erase cycles
Manual Reset capability
100 year data retention
Industrial and extended temperature ranges
8-pin DIP, SOIC, TSSOP, MSOP or TDFN
(3 x 3mm foot-print) packages
—
TDFN max height is 0.8mm
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.
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 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 is 3 x 3mm.
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 impe-
dance comparator drives the open drain output, V
LOW
,
whenever the sense voltage is below 1.25V threshold.
DESCRIPTION
The CAT1026 and CAT1027 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 techno–
logy. 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
© 2007 Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
1
Doc. No. 3010 Rev. L
CATALYST [ CATALYST SEMICONDUCTOR ]
