Voltage Supervisor with I²C Serial 2k-bit CMOS EEPROM, Manual Reset and Watchdog Timer

The CAT1023 is a complete memory and supervisory solution 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 CAT1023 provides a precision V_CC sense circuit and two open drain outputs: one (RESET) drives high and the other (RESET) drives low whenever V_CC falls below the reset threshold voltage. Write operations are disabled if WP is connected to a logic high.

The supervisor has 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. 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 5V, 3.3V and 3V 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 V_CC sense circuit that prevents writes to memory whenever V_CC falls below the reset threshold or until V_CC reaches the reset threshold during power up.

Available packages include an 8-pin DIP, 8-pin SOIC, 8-pin TSSOP, 8-pin TDFN and 8-pin MSOP. The TDFN package thickness is 0.8mm maximum. TDFN footprint options are 3x3mm.