MAX697

MAX696/MAX697 Microprocessor Supervisory Circuits General Description The MAX696/MAX697 supervisory circuits reduce the complexity and number of components required for power-supply monitoring and battery-control functions in microprocessor (μP) systems. These include μP reset and backup-battery switchover, watchdog timer, CMOS RAM write protection, and power-failure warning. The MAX696/MAX697 significantly improve system reliability and accuracy compared to that obtained with separate ICs or discrete components. The MAX696 and MAX697 are supplied in 16-pin packages and perform six functions: 1) A reset output during power-up, power-down, and brownout conditions. The threshold for this “lowline” reset is adjustable by an external voltagedivider. 2) A reset pulse if the optional watchdog timer has not been toggled within a specified time. 3) Individual outputs for low-line and watchdog fault conditions. 4) The reset time may be left at its default value of 50ms, or may be varied with an external capacitor or clock pulses. 5) A separate 1.3V threshold detector for power-fail warning, low-battery detection, or to monitor a power supply other than VCC. The MAX696 also has battery-backup switching for CMOS RAM, CMOS microprocessor, or other lowpower logic. The MAX697 lacks battery-backup switching, but has write-protection pins (CE IN and CE OUT) for CMOS RAM or EPROM. In addition, it consumes less than 250 microamperes. Applications ●● Computers ●● Controllers ●● Intellige...