query about difference between PWM channels in F28335.

ashish ahir

i am using f28335 experiment kit. i have configured ePWM2 for which voltage level is (3.4V for high), but when i configure ePWM1, voltage level for high is (3V). why this? Is there any difference between this two PWM channels? can voltage level drops due to frequent use of PWM pins of board?

over 9 years ago

0 ashish ahir over 9 years ago

Expert 1020 points

please reply.

0 Gautam Iyer over 9 years ago in reply to ashish ahir

Guru 192875 points

Hi Ashish,

There's no way this should happen. 3.3V should be the max you should observe. Nothing more or less.
Other way to verify this is, output the pulse with 100% duty and measure with a multimeter.

Regards,
Gautam

0 ashish ahir over 9 years ago in reply to Gautam Iyer

Expert 1020 points

ok,gautam. i made more observations.
i am controlling IGBT using this PWM pulses.
(1) when ePWM1A is not connected anywhere, then voltage level is 3.3V. But, when i connect it to IGBT gate, it drops to 3V.
(2) I doubted loading effect, and tried this thing with ePWM2A. In this case, it is not dropping.
How is this possible when each and every configurations of these two PWMs' are same?

0 Aditya BG over 9 years ago in reply to ashish ahir

Expert 1825 points

Hi Ashish,

If you are using TI's control card, please make sure that ePWM1A is behaving same in multiple cards. If so, please check your ePWM1A configuration and the pin is multiplexed to any other functionality at SW side.

-Aditya

0 ashish ahir over 9 years ago in reply to Aditya BG

Expert 1020 points

Hi, Aditya
i have checked this issue on another control card and it is working fine. Thanks.

0 Aditya BG over 9 years ago in reply to ashish ahir

Expert 1825 points

Great :)
-Aditya

0 Brett Larimore over 9 years ago in reply to Aditya BG

TI__Guru 57255 points

My feeling is that the pin that you configured to output ePWM2 was, sometime during evaluation, stressed outside of the datasheet limits for the pin. That stess weakened the pin.

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query about difference between PWM channels in F28335.