PSCLK
OSHT
EPWMxA in
EPWMxA out
Prog. pulse width
(OSHTWTH)
Start OSHT pulse
Sustaining pulses
PSCLK
EPWMxA
EPWMxB
EPWMxA
EPWMxB
Enhanced PWM (ePWM) Module
15.2.2.7.4 Waveforms
shows simplified waveforms of the chopping action only; one-shot and duty-cycle control are
not shown. Details of the one-shot and duty-cycle control are discussed in the following sections.
Figure 15-38. Simple PWM-Chopper Submodule Waveforms Showing Chopping Action Only
15.2.2.7.4.1
One-Shot Pulse
The width of the first pulse can be programmed to any of 16 possible pulse width values. The width or
period of the first pulse is given by:
T
1stpulse
= T
SYSCLKOUT
× 8 × OSHTWTH
Where T
SYSCLKOUT
is the period of the system clock (SYSCLKOUT) and OSHTWTH is the four control bits
(value from 1 to 16)
shows the first and subsequent sustaining pulses.
Figure 15-39. PWM-Chopper Submodule Waveforms Showing the First Pulse and
Subsequent Sustaining Pulses
1540
Pulse-Width Modulation Subsystem (PWMSS)
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated