6

with

level is set to 9V. If the pin is grounded the func-

tion is inhibited (i.e. no intermediate step during

the firing).

Third step

order to ensure an appropriate drive to minimize

the power losses. The external power device is

considered in overload whenever the voltage on

setting at a certain level, by means of a resistive

divider, the ON_LEV_PROG pin according to the

following formula:

with

and

level is set to 7.5V.

The overload status is signalled via the ALARM

THERMAL PROCEDURE

As the junction temperature raises, two different

events will take place. When the Over Tempera-

°C is reached, the

ALARM output is activated (low level). If the tem-

perature keeps on raising, up to the Over Tem-

°C Typ) the output

power device is turned off until the temperature

decrease. To prevent an oscillating behaviour

both the thresholds have a built-in hysteresis of

20

°C.

UNDERVOLTAGE LOCK OUT

To avoid operation with non optimal drive of the

external power device, an Undervoltage Lockout

function is implemented. The OUT1 pin is forced

reached the

Undervoltage Upper Threshold

built-in hysteresis will thus avoid intermittent func-

tioning of the device at low supply voltage that

may have a superimposed ripple.

Vs

D94IN126B

Vccth

Vcchys

Undervoltage Comparator Hysteresis

L6353

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