Texas Instruments TMS570LC4357

Duty
1/8
Duty
2/8
Duty
3/8
Duty
4/8
Duty
5/8
Duty
6/8
Duty
7/8
PSCLK
12.5%
25%
37.5%
50%
62.5%
75%
87.5%
PSCLK Period
PSCLK
period
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SPNU563A–March 2018
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Enhanced Pulse Width Modulator (ePWM) Module
35.2.6.4.2 Duty Cycle Control
Pulse transformer-based gate drive designs need to comprehend the magnetic properties or
characteristics of the transformer and associated circuitry. Saturation is one such consideration. To assist
the gate drive designer, the duty cycles of the second and subsequent pulses have been made
programmable. These sustaining pulses ensure the correct drive strength and polarity is maintained on the
power switch gate during the on period, and hence a programmable duty cycle allows a design to be
tuned or optimized via software control.
Figure 35-34 shows the duty cycle control that is possible by programming the CHPDUTY bits. One of
seven possible duty ratios can be selected ranging from 12.5% to 87.5%.
Figure 35-34. PWM-Chopper Submodule Waveforms Showing the Pulse Width (Duty Cycle) Control of
Sustaining Pulses