IMP692A

The IMP690A/IMP692A/IMP802L/IMP802M/IMP805L simplify power supply monitoring and control in microprocessor systems. Each circuit implements four functions: Reset control, watchdog monitoring, batterybackup switching and power-failure monitoring. In addition to microprocessor reset under powerup and power-down conditions, these devices provide battery-backup switching to maintain control in powerloss and brown-out situations. Additional monitoring capabilities can provide an early warning of unregulated power-supply loss before the voltage regulator drops out. The important features of these four functions are:
a) 1.6 second watchdog timer to keep microprocessor responsive
b) 4.40V or 4.65V VCC threshold for microprocessor reset at power-up and power-down
c) SPDT (single-pole, double-throw) PMOS switch connects backup power to RAM if VCC fails
d) 1.25V threshold detector for power loss or general purpose voltage monitoring

While these features are pincompatible with the industry standard powersupply supervisors offered by Maxim, the IMP devices are superior replacements and can reduce power requirements by 70 percent when compared to Maxim MAX690/MAX692A/MAX802L/MAX802M/ MAX805L devices. Short-circuit and thermal protection have also been added.

The IMP690A/IMP802L/IMP805L generate a reset pulse when the supply voltage drops below 4.65V, and the IMP692A/IMP802M generate a reset below 4.40V. The IMP802L/IMP802M have powerfail accuracy to ±2%. The IMP805L is the same as the IMP690A except that RESET is provided instead of RESET .