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 technology. Memory interface is via a 400kHz I2C bus. The CAT1026 and CAT1027 provide a precision VCC sense circuit with five reset threshold voltage options that support 5V, 3.3V and 3V systems. The power 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.