DESCRIPTION

The DS1705/DS1706 3.3- or 5.0-Volt MicroMonitor monitors three vital conditions for a microprocessor:

power supply, software execution, and external override. A precision temperature compensated reference and comparator circuit monitor the status of VCC at the device and at an upstream point for maximum protection. When the sense input detects an out-of-tolerance condition, a non-maskable interrupt is generated. As the voltage at the device degrades, an internal power fail signal is generated which forces the reset to an active state. When VCC returns to an in-tolerance condition, the reset signal is kept in the active state for a minimum of 130 ms to allow the power supply and processor to stabilize.

The second function the DS1705/DS1706 performs is pushbutton reset control. The DS1705/DS1706 debounces the pushbutton input and guarantees an active reset pulse width of 130 ms minimum.

The third function is a watchdog timer. The DS1705/DS1706 has an internal timer that forces the WDS output signal to the active state if the strobe input is not driven low prior to time-out.

FEATURES

■ Halts and restarts an out-of-control microprocessor

■ Holds microprocessor in check during power transients

■ Automatically restarts microprocessor after power failure

■ Monitors pushbutton for external override

■ Accurate 5, 10 or 20 resets for 3.3V systems and 5 or 10 resets for 5.0V systems

■ Eliminates the need for discrete components

■ 3.3V 20 tolerance for use with 3.0V systems

■ Pin-compatible with the MAXIM MAX705/MAX706 in 8-pin DIP, 8-pin SOIC, and μ-SOP

■ 8-pin DIP, 8-pin SOIC and 8-pin μ-SOP packages

■ Industrial temperature range -40C to +85C