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CAT1026, CAT1027 Dual Voltage Supervisory Circuits with IC Serial 2k-bit CMOS EEPROM supply monitor and reset circuit protects memory and FEATURES systems controllers during power up/down and Precision V Power Supply Voltage Monitor CC against brownout conditions. If power supply voltages 5 V, 3.3 V and 3 V systems are out of tolerance reset signals become active preventing the system microcontroller, ASIC, or Five threshold voltage options peripherals from operating. Additional voltage monitoring Externally adjustable down to 1.25 V The CAT1026 features two open drain reset outputs: one (RESET) drives high and the other (RESET) Watchdog timer (CAT1027 only) drives low whenever V falls below the threshold. CC Active High or Low Reset Reset outputs become inactive typically 200ms after Valid reset guaranteed at V = 1 V the supply voltage exceeds the reset threshold value. CC 2 With both active high and low reset signals, interface 400 kHz I C Bus to microcontrollers and other ICs is simple. CAT1027 2.7 V to 5.5 V Operation has only a RESET output. In addition, the RESET pin Low power CMOS technology can be used as an input for push-button manual reset capability. 16-Byte Page Write Buffer Built-in inadvertent write protection The CAT1026 and CAT1027 provide an auxiliary 1,000,000 Program/Erase cycles voltage sensor input, V , which is used to monitor a SENSE second system supply. The auxiliary high impedance Manual Reset capability comparator drives the open drain output, V , LOW 100 year data retention whenever the sense voltage is below 1.25 V threshold. Industrial and extended temperature ranges The CAT1027 is designed with a 1.6 second 8-pin DIP, SOIC, TSSOP, MSOP or TDFN watchdog timer circuit that resets a system to a known (3 x 3 mm foot-print) packages state if software or a hardware glitch halts or hangs TDFN max height is 0.8 mm the system. The CAT1027 features a watchdog timer interrupt input, WDI. For Ordering Information details, see page 19. The on-chip 2k-bit EEPROM memory features a 16-byte page. In addition, hardware data protection is provided DESCRIPTION by a V sense circuit that prevents writes to memory CC whenever V falls below the reset threshold or until V CC CC The CAT1026 and CAT1027 are complete memory reaches the reset threshold during power up. and supervisory solutions for microcontroller-based systems. A 2k-bit serial EEPROM memory and a Available packages include 8-pin DIP and surface system power supervisor with brown-out protection mount, 8-pin SO, 8-pin TSSOP, 8-pin TDFN and 8-pin are integrated together in low power CMOS techno 2 MSOP packages. The TDFN package thickness is logy. Memory interface is via a 400 kHz I C bus. 0.8 mm maximum. TDFN footprint is 3 x 3 mm. The CAT1026 and CAT1027 provide a precision V CC sense circuit with five reset threshold voltage options that support 5 V, 3.3 V and 3 V systems. The power 2009 SCILLC. All rights reserved. 1 Doc. No. MD-3010 Rev. P Characteristics subject to change without notice