1 Pulse-Width Modulation (PWM)

PWM modules generate pulse-width modulated digital signals. In a typical PWM signal, the base frequency is fixed, while the pulse-width is variable (see Figure 1-1). The pulse-width, also referred to as duty cycle, is directly proportional to the amplitude of the original unmodulated signal as shown in Equation 1-1. For example, if a 2.5V output signal is desired, and the PWM signal has a logic high voltage of 5V and a logic low of 0V, a PWM signal with a duty cycle of 50% will suffice. A 50% duty cycle means that for half of the period, the PWM outputs 5V and the average output per period is 2.5V.

$V_{OUT}=A\times DutyCycle$

$where:$

$A=Logic\prime high\prime voltageamplitude$