CAT1025

CAT1024, CAT1025 Supervisory Circuits with EEPROM Serial 2k-bit I2C and Manual Reset Description The CAT1024 and CAT1025 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 400 kHz I2C bus. The CAT1025 provides 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 CAT1025 also has a Write Protect input (WP). Write operations are disabled if WP is connected to a logic high. The CAT1024 also provides a precision VCC sense circuit, but has only a RESET output and does not have a Write Protect input. 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 CAT1024 and CAT1022, the watchdog timer monitors the SDA signal. 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 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 typ...