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PWM dead-band control and HRPWM in Piccolo

John J Wu
Genius 3870 points

We would like to utilize the HRPWM output from something like a TMS320F2802x (e.g. LaunchPad XL) to generate a sine wave. The output of the PWM will be complementary drive signals connected to a half bridge driver. I was hoping to use the dead-band submodule in the DSP, however, it appears that will not work if the PWMA output is fed through the HRPWM section.

Our options as I understand it are:

1. Use an additional PWMA channel with HRPWM but configured with the opposite polarity and adjust the CMPA thresholds to achieve dead-band protection

2. Use a half-bridge driver with built-in shoot-through protection

Did I miss anything?

Thanks,

John

  • 0
    TI__Genius 10820 points

    Hi John,

    Your understanding is correct for the most part. On 2802x devices, xB PWM outputs are not hi-res. If you want HRPWMs to drive both high-side and low-side switches of the half bridge, you will need to use the xA output of a second PWM module and adjust the CMP value to provide dead-band.

    There is another option. If the two PWM waveforms are always complementary to each other, you may generate a signal that is inverted version of xA PWM on xB output by using HRCNFG[SELOUTB] register bit. In this case, you will need to add dead-band externally.

    I hope this helps.

    Hrishi