© Semiconductor Components Industries, LLC, 2011
November, 2011 − Rev. 18
1 Publication Order Number:
CAT1021/D
CAT1021, CAT1022,
CAT1023
Supervisory Circuits with
I
2
C Serial 2k-bit CMOS
EEPROM, Manual Reset and
Watchdog Timer
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 400 kHz I
2
C 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 VCC 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 5 V, 3.3 V and 3 V
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 VCC
sense circuit that prevents writes to memory whenever VCC falls below the reset threshold or until VCC reaches the reset
threshold during power up.
Available packages include an 8−pin PDIP and surface mount 8−pin SO, 8−pin TSSOP, 8−pin TDFN and 8−pin MSOP
packages. The TDFN package thickness is 0.8 mm maximum. TDFN footprint options are 3 x 3 mm.
Features
• Precision Power Supply Voltage Monitor
♦ 5 V, 3.3 V and 3 V Systems
♦ Five Threshold Voltage Options
• Watchdog Timer
• Active High or Low Reset
♦ Valid Reset Guaranteed at VCC = 1 V
• 400 kHz I
2
C Bus
• 2.7 V to 5.5 V 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
• Industrial and Extended Temperature Ranges
• 8−pin DIP, SOIC, TSSOP, MSOP or TDFN (3 x 3 mm
Foot−print) Packages
♦ TDFN Max Height is 0.8 mm
• These Devices are Pb−Free, Halogen Free/BFR Free
and are RoHS Compliant
ORDERING INFORMATION
http://onsemi.com
PDIP−8
CASE 646AA
SOIC−8
CASE 751BD
TSSOP−8
CASE 948S
MSOP−8
CASE 846AD
TDFN−8
CASE 511AL
For Ordering Information details, see page 13.
