LTC1235 Datasheet | Linear Technology

Microprocessor Supervisory Circuit Features n Guaranteed Reset Assertion at VCC = 1V n 1.5m A Maximum Supply Current n Fast (35ns Max.) Onboard Gating of RAM Chip Enable Signals n Conditional Battery Backup Extends Battery Life n 4.65V Precision Voltage Monitor n Power OK/Reset Time Delay: 200ms n External Reset Control n Minimum External ponent Count n 1μA Maximum Standby Current n Voltage Monitor for Power Fail or Low Battery Warning n Thermal Limiting n Performance Specified Over Temperature n All the LTC695 Features Plus Conditional Battery Backup and External Reset Control APPLICATIONS n Critical μP Power Monitoring n Intelligent Instruments n Battery-Powered puters and Controllers n Automotive Systems L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. DESCRIPTION The LTC®1235 provides plete power supply monitoring and battery control functions for microprocessor reset, battery backup, RAM write protection, power failure warning and watchdog timing. The LTC1235 has all the LTC695 Features plus conditional battery backup and external reset control. When an out-of-tolerance power supply condition occurs, the reset outputs are forced to active states and the Chip Enable output write-protects external memory. The RESET output is guaranteed to remain logic low with VCC as low as 1V. External reset control is provided by a debounced pushbutton reset input. The LTC1235 powers the active CMOS RAMs with a charge pumped NMOS power switch to achieve low dropout and low supply current. When primary power is lost, auxiliary power, connected to the battery input pin, provides backup power to the RAMs. The LTC1235 can be programmed by a P signal to either back up the RAMs or not. This extends the battery life in situations where RAM data need not always be saved when power goes down. For an early warning of impending power failure, the LTC1235 provides an internal...