L9611 datasheet(5/12 Pages) STMICROELECTRONICS

5 / 12 page

After the overcurrent protection time is reached, the

powerMOS is switched-off ; this condition is latched

by setting an internal flip-flop and is externallymoni-

tored by the low state of the MON pin.

To resetthe latch the supply voltage hasto fall below

VSL or the device must be switched off.

UNDER AND OVERVOLTAGE SENSE WITH

LOAD DUMP PROTECTION

The undervoltage detection feature resets the timer

and switches off the output driving signal when the

supply voltage is less than VSL.

If the supply voltage exceeds the max operating

supply voltage value, an internal comparator dis-

ables the charge pump, the oscillator and the exter-

nal powerMOS.

In both cases the thresholds are provided with suit-

able hysteresis values.

The load dump protection function allows the device

to withstand - for a limited time - high overvoltages.

It consists of an active clamping diode which limits

the circuit supply voltage to VCLAMP and an external

current limiting resistor R1. The maximum pulse

supply current (see abs. max. ratings is equal to

0.3A. Therefore the maximum load dump voltage is

given by :

VDUMP =VSC + 0.3R1

In this condition the gate of the powerMOS is held

at the GND pin potential and thus the load voltage

is :

VL =Vs - VCLAMP -VGS

Figure 1 : Typical Transfer Curve.

L9610C - L9611C

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