L6285S datasheet(8/16 Pages) STMICROELECTRONICS

Part #	L6285S

Description	3 CHANNELS MULTIPOWER SYSTEM

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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These two channels drive two unipolar stepper

motors in chopping mode. The basic channel con-

figuration is shown in Fig 4. by considering well

known the PWM Current Control Loop behaviour

here below only particular trick are underlined.

During DM3 off period the low side DMOS DM1

and DM2 are switched on to reduce the power

dissipation.

The drain overvoltages generated because of the

stray inductance of the motor windings are limited

by connecting the DZ1 external zener diode to the

clamp pin.. The diodes CL1 and CL2 are inte-

grated as far as the CL3 diode which limits the

negative voltage at pin COM1.2. An internal RC

network (1

µs) is realized to filter the sensing re-

sistor signal.

Figure.4: Unipolar motor driver CHA (or CHB)

L6285

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L6285S Datasheet(PDF) 8 Page - STMicroelectronics