UCC28019: PIN5-Vcomp fail issue!

Hi Jothur,

Is it easy to reproduce the failure phenomenon during on/off when changing to a new UCC28019 sample?

If you can reproduce the failure, can you test the voltage on the Vcomp  and VCC to see whether the voltages on these pins meet UCC28019 absolutely  voltage rating?

Hi, David:

                Please refer attached photo, CH1 is Vcomp，CH4 is Vcc

Vcc voltage is normal, but Vcomp haven't voltage

Hi Yang,

Is the waveform happens at the moment UCC28019 failure?

I do not see any unexpected signal from your waveform. the Vcomp and VCC all under the absolute maximum rating. the Vcomp depends on the output power, so if the vcomp keeps near zero, the output power is at very light load.

please offer me more information, for example, at what condition you find UCC28019 failure(input voltage, output voltage, load ), can offer me the schematic .

thanks.

Hi, David:

                 The input Vcc form power board about 15.5V, application is 2.5KW fan control, please refer attached schematics,

PFC chock TP2, TP5 connect PFC TP1，TP2

Add the other schematics!

Hi Yang：

I look through the schematic and I do not see anything unexpected.

VCC=15.5V is an expected voltage, no problem.

I ask so many question from beginning, but receive no reply. please help answer it one by one.

thanks,

for example:

can you reproduce the failure?

At what condition you trigger the failure?

Hi, David:

                 It's hard to reproduce the failure, customer test the product and turn off it, and restart again, found the function fail, 

and the fail rate only 5 pcs til now, but end customer want to know what root cause is? Why only PIN 5 fail?

so we need your help to analysis this issue, thanks a lot!

Hi Yang,

Does the failure of UCC28019 accompany with other devices, for example PFC mos?

I do not think UCC28019 pin Vcomp can be failed excepted ESD. Please take attention to ESD.

By the way, it is suggested from Cree that Sic Mosfet have a negative voltage on the Driving, and I see you do not have negative voltage here.

Actually, you can only offer me some waveform when working in normal mode, and you can not reproduce the failure, so from your information, I can not imagine what happen during the failure process.

I would suggest you do more FA analysis, maybe you can have some useful information from FA analysis.

Hi David,

Customer want to know what kind of conditions that could cause pin 5 got damaged? Could you list the possibility of causes then customer can check it one by one. 

Besides, if VINS, VSENSE have voltage early than VCC that would damage this device?

Thanks a lot.

VIncent Chen

Hi David,

If RC parts which connected on Vcomp pin is floating, would it has chance to cause part damaged?

Thanks a lot.

VIncent Chen

Hi David,

It's a urgent case, do you have any comment?

Thank you.

Vincent