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:
- A reset output during power-up, power-down, and brownout conditions. The threshold for this "lowline" reset is adjustable by an external voltage-divider.
- A reset pulse if the optional watchdog timer has not been toggled within a specified time.
- Individual outputs for low-line and watchdog fault conditions.
- The reset time may be left at its default value of 50ms, or may be varied with an external capacitor or clock pulses.
- 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 low-power logic.
The MAX697 lacks battery-backup switching, but has write-protection pins (active-low CE IN and active-low CE OUT) for CMOS RAM or EPROM. In addition, it consumes less than 250 microamperes.
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