MAX697 Datasheet

• Adjustable Low-Line Monitor and Power-Down Reset
• Power-OK/Reset Time Delay
• Watchdog Timer—100ms, 1.6s, or Adjustable
• Minimum Component Count
• 1µA Standby Current
• On-Board Gating of Chip-Enable Signals (MAX697)
• Separate Monitor for Power-Fail or Low-Battery Warning

• Computers
• Controllers
• Critical µP Power Monitoring
• Intelligent Instruments

The 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 MAX697 significantly improve system reliability and accuracy compared to that obtained with separate ICs or discrete components.

The 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 voltage-divider.
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 V_CC.

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.