General Description
The MAX690 Family of supervisory circuits reduce the complexity and number of components required for power supply monitoring and battery control functions in microprocessor systems. These include µP reset and backup-battery switchover, watchdog timer, CMOS RAM write protection, and power-failure warning. The MAX690 Family significantly improves system rehability and accuracy compared to that obtainable with separate ICs or discrete components. The MAX690, MAX692 and MAX694 are supplied in 8-pin packages and provide four functions:
1) A Reset output during power-up, power-down and brownout conditions.
2) Battery backup switching for CMOS RAM, CMOS microprocessor or other low power logic.
3) A Reset pulse if the optional watchdog timer has not been toggled within a specified time.
4) A 1.3V threshold detector for power fail warning, low battery detection, or to monitor a power supply other than +5V.
The MAX691, MAX693 and MAX695 are supplied in 16-pin packages and perform all MAX690/692/694 functions, plus:
1.- Write protection of CMOS RAM or EEPROM.
2.- Adjustable reset and watchdog timeout periods.
3.- Separate outputs for indicating a watchdog timeout, backup-battery switchover, and low Vcc.
Applications
Computers
Controllers Intelligent Instruments Automotive Systems
Critical µP Power Monitoring
Features
- Precision Voltage Monitor
4.65V in MAX690, MAX691, MAX694 and MAX695
4.40V in MAX692 and MAX693
- Power OK/Reset Time Delay - 50, 200ms, or adjustable
- Watchdog Timer - 100ms, 1.6 sec, or adjustable
- Minimum Component Count
- 1µA Standby Current
- Battery Backup Power Switching
- Onboard Gating of Chip Enable Signals
- Voltage Monitor for Power Fail or Low Battery Warning.
