00905b

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Unformatted text preview: 1 FIGURE 7: HIGH-SIDE BDC MOTOR DRIVE CIRCUIT VCC VCC 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 Voltage 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.

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