C167CS datasheet(346/517 Pages) INFINEON

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C167CS

Derivatives

The Pulse Width Modulation Module

User’s Manual

17-5

V2.0, 2000-07

Mode 1: Symmetrical PWM Generation (Center Aligned PWM)

Mode 1 is selected by setting the respective bit PMx in register PWMCON1 to ‘1’. In this

mode the timer PTx of the respective PWM channel is counting up until it reaches the

value in the associated period shadow register. Upon the next count pulse the count

direction is reversed and the timer starts counting down now with subsequent count

pulses until it reaches the value 0000H. Upon the next count pulse the count direction is

reversed again and the count cycle is repeated with the following count pulses.

The PWM output signal is switched to a high level when the timer contents are equal to

or greater than the contents of the pulse width shadow register while the timer is counting

up. The signal is switched back to a low level when the respective timer has counted

down to a value below the contents of the pulse width shadow register. So in mode 1 this

PWM value controls both edges of the output signal.

Note that in mode 1 the period of the PWM signal is twice the period of the timer:

PWM_PeriodMode1 = 2 × ([PPx] + 1)

Figure 17-4 illustrates the operation and output waveforms of a PWM channel in mode 1

for different values in the pulse width register. This mode is referred to as Center Aligned

PWM, because the value in the pulse width (shadow) register effects both edges of the

output signal symmetrically.

C167CS Datasheet(PDF) 346 Page - Infineon Technologies AG