L6377 datasheet(11/16 Pages) STMICROELECTRONICS

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L6377

Demagnetisation of inductive loads

11/16

Demagnetisation of inductive loads

The L6377 has an internal clamping zener diode able to demagnetise inductive loads. Note

that the limitation comes from the peak power that the package can handle. Attention must

be paid to a proper thermal design of the board. If, for whatever reason (load current or

inductive value too big) the peak power dissipation is too high, an external Zener plus Diode

arrangement, can perform a demagnetisation versus Ground or versus Vs (see fig 5 and 6).

The breakdown voltage of the external Zener Diode must be chosen considering the internal

clamping voltage (Vcl) and the supply voltage (Vs) according to:

Vz < Vcl(min)-Vs(max)

for demagnetisation versus ground or

Vs(max)<Vz<Vcl(min)

for demagnetisation versus Vs.

Figure 7.

External demagnetisation circuit (versus ground)

Figure 6.

Input comparator hysteresis

Vi+

Vout

100mV

D94IN079

Vi-

100mV

DRIVER

OVC

OUT

SHORT CIRCUIT

CONTROL

CURRENT

LIMIT

D94IN112

VZ < Vcl (min) - VS (max)

L6377 Datasheet(PDF) 11 Page - STMicroelectronics