TMS570LS1114: EPWM4A and EPWM4B has two different output level

Hi Marvin,

Both PWM4A and PWM4B should have the same output level (3.3V). Is there an external pull-down resistor on ePWM4A or ePWM4B signal?

Hi QJ,

Thanks for the response. I will ask the customer about this and will let you know.

Regards,

Marvin

Thanks Marvin

Hi QJ,

The customer has included the screenshot of the circuit for the EPWM4A and EPWM4B and EPWM7A. Behind the 1kOhm Resistor, an amplifier(UCC27517A-Q1) is connected. In+ should have a pull-down resistance.

This does not explain that EPWM4A works.

In addition, they removed R2100, but there was no change in the signal. it was still only half as high as the signal from EPWM4A.

Here are the screenshot;

I hope this helps.

Thank you.

Regards,

Marvin

Hi Marvin,

Which package (ZWT or PGE) of LS1114 is used? I'd like to check it

Hi Qj,

The customer is using TMS5701114ZWTQQ1. 

Is there additional information you needed from the customer? Please let me know.

Thank you.

Regards,

Marvin

Hi Marvin,

I don't have TMS570LS1114ZWT silicon for test. I just measured ePWM4A and ePWM4B on TMS570LC43x LP, both are ok. 

LS1114ZWT and LC43x ZWT are pin-2-pin compatible, and they use the same ePWM IP.

Hi QJ,

Thank you. What do you think is the reason for this issue?

The customer informed me that line from EPWM_4B is also connected to A12(ECLK) which has a pulldown inside. Should they set it to a high impedance via software?

Regards,

Marvin

Hi Marvin,

Thanks for providing more info. Please config ECLK as GIO input without pull, then try again.