General Description

The MAX793/MAX794/MAX795 microprocessor (μP) supervisory circuits monitor and control the activities of +3.0V/+3.3V μPs by providing backup-battery switchover, among other features such as low-line indication, μP reset, write protection for CMOS RAM, and a watchdog (see the Selector Guide below). The backup-battery volt age can exceed VCC, permitting the use of 3.6V lithium batteries in systems using 3.0V to 3.3V for VCC.

The MAX793/MAX795 offer a choice of reset threshold voltage range (denoted by suffix letter): 3.00V to 3.15V (T), 2.85V to 3.00V (S), and 2.55V to 2.70V (R). The MAX794’s reset threshold is set externally with a resistor divider. The MAX793/MAX794 are available in 16-pin DIP and narrow SO packages, and the MAX795 comes in 8-pin DIP and SO packages.

Features

MAX793/MAX794/MAX795

? Precision Supply-Voltage Monitor:

?? Fixed Reset Trip Voltage (MAX793/MAX795)

?? Adjustable Reset Trip Voltage (MAX794)

? Guaranteed Reset Assertion to VCC = 1V

? Backup-Battery Power Switching—Battery

?? Voltage Can Exceed VCC

? On-Board Gating of Chip-Enable Signals—7ns

?? Max Propagation Delay

?? MAX793/MAX794 Only

? Battery Freshness Seal

? Battery OK Output (MAX793)

? Uncommitted Voltage Monitor for Power-Fail or

?? Low-Battery Warning

? Independent Watchdog Timer (1.6s timeout)

? Manual Reset Input

Applications

?? Battery-Powered Computers and Controllers

?? Embedded Controllers

?? Intelligent Controllers

?? Critical μP Power Monitoring

?? Portable Equipment