`ELECTRONIC
`CIRCUITS
`Volume2
`
`Rudolf F. Graf
`
`
`
`Encyclopedia of
`ELECTRONIC
`CIRCUITS
`Volume 2
`Rudolf F. Graf
`
`I TAB I TAB BOOKS
`
`.
`
`Blue Ridge Summit, PA
`
`
`
`FIRST EDITION
`SEVENTH PRINTING
`
`© 1988 by Rudolf F. Graf.
`Published by TAB Books.
`TAB Books is a division of McGraw-Hill, Inc.
`
`Printed in the United States of America. All rights reserved . The publisher takes no
`responsibility for the use of any of the materials or methods described in this book,
`nor for the products thereof.
`
`Library of Congress Cataloging-in-Publication Data
`
`(Revised for v. 2)
`
`Graf, Rudolf F.
`Encyclopedia of electronics circuits-Volume 2.
`
`Bibliography: v. 1, p.
`Includes indexes.
`I. Title.
`1. Electronic circuits.
`TK7867.G66 1985
`621.3815'3
`ISBN 0-8306-0938-5 (v. 1)
`ISBN 0-8306-1938-0 (pbk. : v. 1)
`ISBN 0-8306-9138-3 (v. 2)
`ISBN 0-8306-3138-0 (pbk.: v. 2)
`
`84-26772
`
`TAB Books offers software for sale. For information and a catalog, please contact
`TAB Software Department, Blue Ridge Summit, PA 17294-0850.
`
`
`
`PWM MOTOR SPEED CONTROL
`03 .
`MR854
`
`MOTOR
`ARMATURE
`
`'/3 HP
`90 Vdc
`
`R1
`
`01
`MGP20N45
`
`R2
`1 Mn
`
`VREF
`INPUT
`
`COMPARATOR
`
`MOTOROLA
`
`02
`MGP20N45
`
`RS
`47 n
`
`C1
`.1 µF
`
`120 V AC
`0 2 LINE VOLTAGE
`
`Fig. 60-3
`
`Circuit Notes
`Speed control is accomplished by pulse width modulating the gates of two MGP20N45
`TMOS devices. Therefore, motor speed is proportional to the pulse width of the incoming
`digital signal, which can be generated by a microprocessor or digital logic.
`The incoming signal is applied to comparator Ul, then to paralleled inverters U2,
`U3, and U4 that drive the two TMOS devices, which, in turn, control power applied
`to the motor armature. Bridge rectifier Dl supplies fullwave power that is filtered by
`R5 and Cl. Free-wheeling diode D3 (MR854) prevents high voltage across Ql and Q2.
`A back-to-back zener diode, D2, protects against transients and high voltage surges.
`
`STEPPING MOTOR DRIVER
`
`Circuit Notes
`Stepping motors find wide use in disk drives
`and machine control. MOSPOWER transistors
`are ideal motor drivers because of their freedom
`from second breakdown. Note that snubbing
`networks are not used because load line shaping
`is not necessary with MOSPOWER and the
`inductance of the motor is fairly low so that the
`inductive spike is small. The MOSFET gates
`are tied directly to the outputs of the CMOS
`control circuitry. The logic is arranged to
`sequence the motor in accordance with the
`needs of the application.
`
`0,-04: VN10KM OR V01000CJ
`
`SILCONIX, INC.
`
`Fig. 60-4
`
`376
`
`