CAT1021, CAT1022,
CAT1023
Supervisory Circuits with
2
EEPROM Serial 2k-bit I C
Manual Reset and
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Watchdog Timer
Description
The CAT1021, CAT1022 and CAT1023 are complete memory and
supervisory solutions for microcontrollerbased systems. A EEPROM
2
Serial 2kbit I C memory and a system power supervisor with
SOIC8 TSSOP8
brownout protection are integrated together in low power CMOS
2 CASE 751BD CASE 948S
technology. Memory interface is via a 400 kHz I C bus.
The CAT1021 and CAT1023 provide a precision VCC 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
MSOP8 TDFN8
Write Protect input. The CAT1021 also has a Write Protect input
CASE 846AD CASE 511AL
(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
ORDERING INFORMATION
timer monitors the SDA signal. The CAT1023 has a separate watchdog
For Ordering Information details, see page 13.
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 pushbutton manual reset capability.
The onchip, 2kbit EEPROM memory features a 16byte 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 surface mount 8pin SOIC, 8 pin TSSOP, 8 pin TDFN and 8pin 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 Builtin Inadvertent Write Protection
5 V, 3.3 V and 3 V Systems WP Pin (CAT1021)
Five Threshold Voltage Options
1,000,000 Program/Erase Cycles
Watchdog Timer
Manual Reset Input
Active High or Low Reset
100 Year Data Retention
Valid Reset Guaranteed at VCC = 1 V
Industrial and Extended Temperature Ranges
2
400 kHz I C Bus
8pin SOIC, TSSOP, MSOP or TDFN (3 x 3 mm
2.7 V to 5.5 V Operation
Footprint) Packages
Low Power CMOS Technology TDFN Max Height is 0.8 mm
16Byte Page Write Buffer These Devices are PbFree, Halogen Free/BFR Free
and are RoHS Compliant
Semiconductor Components Industries, LLC, 2011
1 Publication Order Number:
May, 2018 Rev. 19 CAT1021/DCAT1021, CAT1022, CAT1023
Table 1. THRESHOLD VOLTAGE OPTION
Part Dash Minimum Maximum
Number Threshold Threshold
45 4.50 4.75
42 4.25 4.50
30 3.00 3.15
28 2.85 3.00
25 2.55 2.70
BLOCK DIAGRAM
EXTERNAL LOAD
SENSEAMPS
D
OUT
SHIFT REGISTERS
ACK
V
CC
WORDADDRESS COLUMN
V
SS
BUFFERS DECODERS
START/STOP
SDA
LOGIC
2kbit
EEPROM
XDEC
CONTROL
WP LOGIC
( AT1021)C
DATA IN STORAGE
HIGHVOLTAGE/
TIMING CONTROL
RESET Controller
STATE COUNTERS
SCL
Precision SLAVE
MR ADDRESS
Vcc Monitor
COMPARATORS
WDI
RESET
(CAT1023)
(CAT1021/23) RESET
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