L6219DSA datasheet(5/8 Pages) STMICROELECTRONICS

5 / 8 page

Single-pulse Generator

The pulse generator is a monostable triggered on

the positive going edge of the comparator output.

The monostable output is high during the pulse

time, toff , which is determined by the time compo-

nents Rt and Ct.

toff = 1.1

• RtCt

The single pulse switches off the power feed to

the motor winding, causing the winding current to

decrease during toff.

If a new trigger signal should occur during toff,it is

ignored.

Output Stage

The output stage contains four Darlington transis-

tors (source drivers) four saturated transistors

(sink drivers) and eight diodes, connected in two

H bridge.

The source transistors are used to switch the

power supplied to the motor winding, thus driving

a constant current through the winding.

It should be noted however, that is not permitted

to short circuit the outputs.

Internal circuitry is added in order to increase the

accuracy of the motor current particularly with low

current levels.

Figure 2: Principle Operating Sequence

L6219DSA

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