TMS320F28384D: How to synchronize ADC triggering with a variable frequency PWM in C2000?

Part Number: TMS320F28384D

Tool/software:

Hi everyone,

I’m working on a C2000-based converter where the PWM switching frequency varies dynamically during operation.
I want to synchronize my ADC conversions precisely with the PWM signal, so the ADC trigger adapts automatically as the PWM frequency changes.

Currently, I’m configuring the ADC SOC trigger source to the PWM trigger (e.g., EPWM1_SOCB) and setting up the prescaler to control the trigger frequency.
My questions are:

  1. Is this approach the recommended way to keep ADC sampling synchronized with a variable PWM frequency?

  2. Are there any known limitations or timing constraints I should be aware of when the PWM frequency changes?

  3. How can I ensure the ADC trigger timing adjusts correctly without losing accuracy or causing missed conversions?

  4. Are there examples or best practices from TI for this kind of synchronization?

Thanks in advance for your help!

  • Hi Glac,

    EPWM SOC triggering of ADC is common practice.  This will take care of dynamic PWM switching frequency.  If you are using multiple ADCs, please ensure that they are converting synchronously, meaning that if all 4 ADC modules are used, the trigger source and sampling time for the 4 ADC modules (A, B, C and D) are the same to ensure synchronous operation (vs async).  This will ensure that accuracy is not degraded.  Asynchronous mode of operation would cause unintended coupling during sampling and quantization phases which would translate to lower accuracy.

    More on synchronous operation under section 10.13 Additional Information (subsection 20.13.1 Ensuring Synchronous Operation) in the Technical Reference Manual (SPRUII0F).

    Regards,

    Joseph