GENERAL DESCRIPTION

The TC70/71 is a fully-integrated power supply monitor, watchdog and battery backup circuit in a space-saving 8-pin package.

When power is initially applied, the TC70/71 holds the processor in its reset state for a minimum of 500msec after VCC is in tolerance to ensure stable system start-up. After start-up, processor sanity is monitored by the on-board watchdog circuit. The processor must provide periodic high-to-low level transitions to the TC70/71 to verify proper execution. Should the processor fail to supply this signal within the specified timeout period, an out-of-control processor is indicated and the TC70/71 issues a momentary processor reset as a result. The TC70 also features a watchdog disable pin to facilitate system test and debug.

FEATURES

■ Maximum Functional Integration: Precision Power

Supply Monitor, Watchdog Timer, External RESET

Override, Threshold Detector and Battery Backup

Controller in an 8-Pin Package

■ Generates Power-on RESET and Guards Against

Unstable Processor Operation Resulting from

Power Brown-out

■ Automatically Halts and Restarts an Out-of

Control Microprocessor

■ Output Can be Wire-ORed, or Hooked to Manual

RESET Pushbutton Switch

■ Watchdog Disable Pin for Easier Prototyping (TC70)

■ Voltage Monitor for Power Fail or Low Battery

Warning (TC71)

■ Available in 8-Pin Plastic DIP or 8-Pin SOIC Packages

■ Cost Effective

TYPICAL APPLICATIONS

■ All Microprocessor-based Systems

■ Test Equipment

■ Instrumentation

■ Set-Top Boxes