SI4779CY Datasheet, PDF (8/8 Pages) Vishay Siliconix – High-Side N-Channel Switch with Current Limit

Si4779CY
Vishay Siliconix
New Product
DETAILED DESCRIPTION
The SI4779CY limits the output current to a user-defined level.
When the output current passes through the main switch a
fraction of this current passes through a replica switch and
R_SET.
R_SET is an external sense resistor used to set the level of the
over current limit; the over current limit should be set between
0.4 A and 2.4 A (see graph for R_SET value vs. current limit).
The circuit shuts down the switch when the current flowing
through the switch exceeds Ilimit. After a short period of time,
the circuit will slowly turn on the switch again. The length of
time off is based on average power consumption, which is
designed to be kept under 500 mW.
If the output is shorted , the circuit will go into an on-off cycle
to protect the switch and to prevent the battery from draining
down.
The fault output (FAULT) goes low when the circuit is in over
current limit or short circuit protection mode. A 100-kW pull-up
resistor from FAULT to IN provides a logic-control signal.
APPLICATIONS DIAGRAM
Line Input
100 mF
100 kW
ON
IN
OUT
100 kW
FAULT
Si4779CY
ON
R_SET
SET
GND
FIGURE 13.
Line Output
100 mF
11 W
www.vishay.com
8
Document Number: 71664
S-04276—Rev. A, 16-Jul-01