L6377 datasheet(9/16 Pages) STMICROELECTRONICS

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L6377

Over current operation

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Over current operation

In order to implement a short circuit protection the output power MOS is driven in linear

mode to limit the output current to the Isc value. This Isc limit is externally settable by means

of an external 1/4 W resistor connected from Rsc pin and GND. The value of the resistor

must be chosen according to the following formula:

Isc (A) = 5/Rsc (kΩ)

with

5 < Rsc < 30 (kΩ)

For

Rsc < 5 (kΩ)

Isc is limited to Isc = 1.1 A (typical value).

This condition (current limited to the Isc value) lasts for a Ton time interval, that can be set

by means of a capacitor (CDON) connected to the ON DELAY pin according to the following

formula:

tON = 1.28 µs/pF

for

50 pF < CDON < 2 nF

After the ton interval has expired the output power MOS is switched off for the tOFF time

interval with:

tOFF = 64*tON.

Figure 5.

Short circuit operation waveforms

OUTPUT

CURRENT

tON

tOFF

Time

t<tON

DIAG

(active low)

Time

Short Circuit

Isc

Iout

D94IN105

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