PWM Controller Pulse Width Modulation Simple Circuits Diagram
This circuit shows a PWM Controller schematic diagram.
Complementary half-H peripheral drivers SN75603 and SN75604 with outputs rated at 40 V and 2.0 A. Capacitor C1 is charged linearly with a constant current of 1 mA from the 1N5297, which is an FET current-regulator diode.
These drivers has the ability to provide bidirectional control which will place the motor in a full-bridge configuration. Motor speed is controlled by feeding a dc voltage of 0 to 10 V to control input pin 5 of U2. As the control voltage increases, the width of the output pulse pin 3 also increases. These pulses control the on/off time of the two motor drivers.
Timer U1 operates in the astable mode at a frequency of 80 Hz. The 100-Ω discharge resistor results in an 8-μs trigger pulse which is coupm led to the trigger input of timer U2. Timer U2 serves as the PWM generator. The trigger pulse width of timer U1 limits the minimum possible duty cycle from U2.