UCC28742: PMP31193 three phase power supply output abnormal

xiaoyu jia

Prodigy 10 points

Part Number: UCC28742
Other Parts Discussed in Thread: PMP31193

Tool/software:

i'm implementing UCC28742 by reference of PMP31193 in a three phase 380VAC design.

the circuit diagram is shown as below, i found that the output of 24V is only around 6V.

I detect the voltage wave form of VDD, it's very similar to the UVLO protection waveform: a saw tooth waveform.

So I measured the following wavefrom as below, but didn't find any issue. Please kindly help me to figure out what's wrong or potential problem in the design, thanks in advance!

5 months ago

0 Mike O' 5 months ago

TI__Guru* 86286 points

Do to high volume this will be look into in the order it was recieved.

0 xiaoyu jia 5 months ago in reply to Mike O'

Prodigy 10 points

thanks for reply, add more details:

change back R109 and R113 to what's defined in PMP31193， R109:261k; R113:56.2k

chanel number:

1.vdd
2.ic drv
3.ic cs
4.vaux

three times retry can be seen in the signals.

zoom in:

change gate resistance 10R to 5R, add 511k and 1nf/1kV in parallel with TVS and add 18pf at CS pin

0 Mike O' 5 months ago in reply to xiaoyu jia

TI__Guru* 86286 points

Hello,

It looks like you are triggering an OVP or OCP fault with the VDD cycling.

The following link will bring you to an application note that describes primary fault sensing that the UCC28742 uses, the issues with it and how to resolve them with proper filtering, snubbing and clamping. I believe this information will help resolve your issue.

https://www.ti.com/lit/pdf/sluaac5

Regards,

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UCC28742: PMP31193 three phase power supply output abnormal