CAT1023

CAT1021, CAT1022, CAT1023 Supervisory Circuits with EEPROM Serial 2k-bit I2C Manual Reset and Watchdog Timer www.onsemi.com Description The CAT1021, CAT1022 and CAT1023 are complete memory and supervisory solutions for microcontroller−based systems. A EEPROM Serial 2k−bit I2C 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 I2C bus. SOIC−8 CASE 751BD TSSOP−8 CASE 948S 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 Write Protect input. The CAT1021 also has a Write Protect input (WP). Write operations are disabled if WP is connected to a logic high. MSOP−8 CASE 846AD TDFN−8 CASE 511AL 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 timer interrupt input pin, WDI. For Ordering Information details, see page 13. 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 pow...