TMS320F280041: Comparators

Jochen Krieger

Dear all,

currently we are evaluating the TMS320F280041 for a new project and need information, if the analog comparator meet our requirements.

The project is a 4x interleaved PFC which has 4 times the below signal to switch off the PWMs. In total 8 comparator channels are needed to avoid reconfiguration during runtime.

The negative Input of the Comparators shall be set to 1.5V via the DAC's.

The PWM's are always running. Turn off shall be either due to timer (duty cycle) or if the comparator triggers.

Switching frequency is like 130kHz (full cycle e.g. between two red lines)

The transition pos->neg should switch off PWMxA

The transition neg->pos should switch off PWMxB

Is this possible without reconfiguration, if the comparators COMPH/COMPL are used?

How shall we connect the Analog signals to reach 8 PWMs, e.g. Pin9(CMP_HP0) & Pin12(CMP_LP1)?

over 8 years ago

0 Frank Ankapong over 8 years ago

TI__Mastermind 28275 points

Hi Jochen,

Yes, this is possible. No reconfiguration should be needed. There is an inverter on the comparator output to invert the trip so you can use this for the pos->neg transition. The 130KHz switching frequency can be easily met by the comparator.

0 Jochen Krieger over 8 years ago in reply to Frank Ankapong

Prodigy 30 points

Hi Frank,
thanks for your comment. Good to hear that it works like that.
My assumption that the analog signal needs to be routed to two Pins, e.g. Pin9 & Pin12 is also right, or is there a way for the mux to route the Signal on Pin9 to both Comparators together?

regards
Jochen

0 Frank Ankapong over 8 years ago in reply to Jochen Krieger

TI__Mastermind 28275 points

Jochen,

Multiple pins can be routed to the comparator positive and negative inputs. Please look at the Analog Subsystem Chapter in the TRM for the full list of possible configurations.

0 Jochen Krieger over 8 years ago in reply to Frank Ankapong

Prodigy 30 points

Hi Frank,

I know that document, my question was more like: Is it possible to only use one pin and route this to multiple comparator inputs? Or do I need to use n pins for n comparators?

From my understanding this is not possible, but would give some more degrees of freedom.

best regards

Jochen

0 Frank Ankapong over 8 years ago in reply to Jochen Krieger

TI__Mastermind 28275 points

Jochen,

Yes, your understanding is correct. The only input options available for a comparator in a group are the analog pins in that group.

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TMS320F280041: Comparators