The MAX807 microprocessor (µP) supervisory circuit reduces the complexity and number of components needed to monitor power-supply and battery-control functions in µP systems. A 70µA supply current makes the MAX807 ideal for use in portable equipment, while a 2ns chip-enable propagation delay and 250mA output current capability (20mA in battery-backup mode) make it suitable for larger, higher-performance equipment.
The MAX807 comes in 16-pin DIP, SO, and TSSOP packages, and provides the following functions:
µP reset. The active-low RESET output is asserted during power-up, power-down, and brownout conditions, and is guaranteed to be in the correct state for VCC down to 1V.
Active-high RESET output.
Manual-reset input.
Two-stage power-fail warning. A separate low-line comparator compares VCC to a threshold 52mV above the reset threshold. This low-line comparator is more accurate than those in previous µP supervisors.
Backup-battery switchover for CMOS RAM, real-time clocks, µPs, or other low-power logic.
Write protection of CMOS RAM or EEPROM.
2.275V threshold detector provides for power-fail warning and low-battery detection, or monitors a power supply other than +5V.
BATT OK status flag indicates that the backup-battery voltage is above +2.275V.
Watchdog-fault output—asserted if the watchdog input has not been toggled within a preset timeout period.
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