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Unformatted text preview: 1 FIGURE 7: HIGH-SIDE BDC MOTOR
R1 BDC D1 Armature BDC D1 Brush BASIC DRIVE CIRCUITS 1. VCC R2 Shunt
Field LOW-SIDE BDC MOTOR
DRIVE CIRCUIT R2 Series
Field FIGURE 6: To Controller DC
Supply COMPOUND-WOUND DC
MOTORS To Controller FIGURE 5: Note that in each circuit there is a diode across the
motor. This diode is there to prevent Back Electromagnetic Flux (BEMF) voltage from harming the MOSFET.
BEMF is generated when the motor is spinning. When
the MOSFET is turned off, the winding in the motor is
still charged at this point and will produce reverse
current flow. D1 must be rated appropriately so that it
will dissipate this current. Motor Resistors R1 and R2 in Figure 6 and Figure 7 are important to the operation of each circuit. R1 protects the
microcontroller from current spikes while R2 ensures
that Q1 is turned off when the input pin is tri-stated. DS00905B-page 3 AN905
Note the diodes across each of the MOSFETs (D1-D4).
These diodes protect the MOSFETs from current spikes
generated by BEMF...
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This note was uploaded on 01/29/2014 for the course AA AA taught by Professor Aa during the Winter '10 term at ENS Cachan.
- Winter '10