SG1549 Datasheet, PDF (1/4 Pages) Microsemi Corporation – CURRENT SENSE LATCH

SG1549/SG2549/SG3549
CURRENT SENSE LATCH
DESCRIPTION
This monolithic integrated circuit is an analog latch device with digital reset. It was
specifically designed to provide pulse-by-pulse current limiting for switch-mode power
supply systems, but many other application are also feasible. Its function is to provide
a latching switch action upon sensing an input threshold voltage, with reset accom-
plished by an external clock signal. This device can be interfaced directly with many
kinds of pulse width modulating control IC's, including the SG1524, SG1525A and
SG1527A.
The input threshold for the latch circuit is 100mV, which can be referenced either to
ground or to a wide-ranging positive voltage. There are high and low-going output
signals available, and both the supply voltage and clock signal can be taken directly
from an associated PWM control chip.
With delays in the range of 200 nanoseconds, this latch circuit is ideal for fast reaction
sensing to provide overall current limiting, short circuit protection, or transformer
saturation control.
FEATURES
• Current sensing with 100mV
threshold
• Common-mode input at ground or
to 40V
• Complementary outputs
• Automatic reset from PWM clock
• 180ns delay
• Interface direct to SG1524,
SG1525A, SG1527A
HIGH RELIABILITY FEATURES
- SG1549
♦ Available to MIL-STD-883
♦ LMI level "S" processing available
♦ Radiation data available
BLOCK DIAGRAM
SCHEMATIC
4/90 Rev 1.1 2/94
Copyright © 1994
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