Datasheet

L6377 Over current operation
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7 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 I
sc
limit is externally settable by means
of an external 1/4 W resistor connected from R
sc
pin and GND. The value of the resistor
must be chosen according to the following formula:
I
sc
(A) = 5/R
sc
(kΩ)
with
5 < R
sc
< 30 (kΩ)
For
R
sc
< 5 (kΩ)
I
sc
is limited to I
sc
= 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 (C
DON
) connected to the ON DELAY pin according to the following
formula:
t
ON
= 1.28 µs/pF
for
50 pF < C
DON
< 2 nF
After the t
on
interval has expired the output power MOS is switched off for the t
OFF
time
interval with:
t
OFF
= 64*t
ON
.
Figure 5. Short circuit operation waveforms
OUTPUT
CURRENT
t
ON
t
ON
t
OFF
t
OFF
Time
t<t
ON
DIAG
(active low)
Time
Short CircuitShort Circuit
I
sc
I
out
D94IN105