STPIC44L02 datasheet(17/21 Pages) STMICROELECTRONICS

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STPIC44L02

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been corrected. An under-battery-voltage fault is

flagged to the controller through FLT. The

under-battery voltage fault is not reported in the

serial fault word. When an under-battery-voltage

condition occurs, the device reports the battery

fault but disables fault reporting for open and

shorted load conditions. When the fault condition

is removed before the CS signal transitates low,

the fault condition is not captured in the serial fault

transition of CS providing that no other faults are

present in the device. Figure 21 illustrates the

operation of the under voltage detection circuit.

Figure 21 : Over Battery Shutdown

INDUCTIVE VOLTAGE TRANSIENTS

A typical application for the pre driver/power FET

circuit is to switch inductive loads. When an

inductive load is switched off, a large voltage spike

can

occur.

These

spikes

can

exceed

the

maximum VDS rating for the external FET and

damage the device when the proper protection is

not in place. The FET can be protected from these

transients through a variety of methods using

external components.

The STPIC44L02 offers that protection in the form

of a zener diode stack connected between the

DRAIN input and GATE output (see figure 22).

Zener diode Z1 turns the FET on to dissipate the

transient energy. GATE diode Z2 is provided to

prevent the gate voltage from exceeding 13V

during normal operation and transient protection.

Figure 22 : Switching Time

EXTERNAL FAULT REFERENCE INPUT

The STPIC44L02 compares each channel drain

voltage to a fault reference to detect shorted-load

and open-load conditions. The user has the option

of using the internal generated 1.25V fault

reference or providing an external reference

voltage through VCOMP. The internal reference is

selected by connecting VCOMPEN to GND and

VCOMP is selected by connecting VCOMPEN to VCC

(see Figure 23). Proper layout techniques should

be used in the grounding network for the VCOMP

circuit on the STPIC44L02. The ground for the

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