SG1544_1 Datasheet, PDF (1/4 Pages) Microsemi Corporation – LOW-VOLTAGE SUPERVISORY CIRCUIT

SG1544/SG2544/SG3544
LOW-VOLTAGE SUPERVISORY CIRCUIT
DESCRIPTION
This device was designed to provide all the operational features of the SG1543/
2543/3543 devices but with the added advantage of uncommitted inputs to the
voltage sensing comparators. This allows monitoring of voltage levels less than
2.5 volts by dividing down the internal reference supply.
In all other respects, the SG1544 series is identical to the SG1543 series. These
monolithic devices contain all the functions necessary to monitor and control the
output of a sophisticated power supply system. Over-voltage sensing with
provision to trigger an external SCR “crowbar” shutdown; an under-voltage circuit
which can be used to monitor either the output or sample the input line voltage;
and a third op amp/comparator usable for current sensing are all included in this
IC, together with an independent, accurate reference generator.
The voltage-sensing input comparators are identical and can be used with
threshold levels from zero volts to (V_IN - 3V). Each has approximately 25mv of
hysteresis which is offset so the switching differential threshold is zero on the non-
inverting input for rising levels and zero on the inverting input for falling signals.
All other operating characteristics are as described in the SG1543 data sheet and
application note.
FEATURES
• Uncommitted comparator inputs for
wide input flexibility
• Common-Mode range from zero to near
supply voltage
• Reference voltage trimmed to 1%
accuracy
• Over-voltage, under-voltage, and current
sensing circuits all included
• SCR "Crowbar" drive of 300mA
• Programmable time delays
• Open-collector outputs and remote
activation capability
• Total standby current less than 10mA
HIGH RELIABILITY FEATURES
- SG1544
♦ Available to MIL-STD-883 and DESC
SMD
♦ LMI level "S" processing available
BLOCK DIAGRAM
Rev 1.1a 3.19.2005
Copyright © 1994
Microsemi Inc.
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