1FEATURES

· Inputs for Monitoring up to Four Separate

Supply Voltage Levels

· Internal Inverter for Sensing a Negative Supply

Voltage

· Line/Switch Sense Input for Early Power

Source Failure Warning

· Programmable Under- and Over-Voltage Fault

Thresholds with Proportional Hysteresis

· A Precision 2.5-V Reference

· General Purpose Op-Amp for Auxiliary Use

· Three High Current, >3 0mA, Open-Collector

Outputs Indicate Over-Voltage, Under-Voltage

and Power OK Conditions

· 8-V to 40-V Supply Operation with 7-mA

Stand-By Current

DESCRIPTION

The UC1903 family of quad supply and line monitor

integrated circuits will respond to under- and

over-voltage conditions on up to four continuously

monitored voltage levels. An internal op-amp inverter

allows at least one of these levels to be negative. A separate line/switcher sense input is available to

provide early warning of line or other power source

failures.

The fault window adjustment circuit on these devices

provides easy programming of under- and

over-voltage thresholds. The thresholds, centered

around a precision 2.5-V reference, have an input

hysteresis that scales with the window width for precise, glitch-free operation. A reference output pin

allows the sense input fault windows to be scaled

independently using simple resistive dividers.

The three open collector outputs on these devices

sink in excess of 30 mA of load current when active.

The under- and over-voltage outputs respond after

separate, user defined, delays to respective fault

conditions. The third output is active during any fault

condition including under- and over-voltage,

line/switcher faults, and input supply under-voltage.

The off state of this output indicates a power OK

situation.