Datasheet

L6376 Short circuit operation
11/18
8 Short circuit operation
In order to allow normal operation of the other inputs when one channel is in short cirtuit, an
innovative non dissipative over current protection (patent pending) is implemented in the
device.
In this way, the temperature of the device is kept enough low to prevent the intervention of
the thermal protection (in most of the cases) and so to avoid the shut down of the whole
device.
If a short circuit condition is present on one output, the current limiting circuit puts that
channel in linear mode — sourcing the ISC current (typically 800 mA) — for a time period
(t
ON
) defined by an external capacitor (C
DON
connected to the ON DELAY pin).
After that period, if the short circuit condition is still present the output is turned off for
another time period (t
OFF
) defined by a second external capacitor (C
DOFF
connected to the
OFF DELAY pin).
When also this period is expired:
● if the short circuit condition is still present the output stays on for the tON period and the
sequence starts again;
● if the short circuit condition is not present anymore the normal operation of the output is
resumed.
The t
ON
and t
OFF
periods are completely independent and can be set from 64 µs to 15 µs,
using external capacitors ranging from 50 pF to 15 nF (1.28 µs/pF).
If the OFF DELAY pin is tied to ground (i.e. the C
DOFF
capacitor is not used) the t
OFF
time
period is 64 times the t
ON
period.
The diagnostic output (DIAG) is active when the output is switched off, while it is not active
when the output is on (i.e. during the t
ON
period) even if in that period a short circuit
condition is present.
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