TIDA-010015: Not working with LLC Mosfets IPA60R120P7XKSA1

Hi Vivek,

    Can I have more info from the issue? Like, what is the failure symptoms on the FETs? What is the test condition?

Regards,

Richard

Issues are below :-

1) UUT off on below 2A current after 2 to 5 Minutes.

2) After UUT off need to do manual restart. ( Self recover not working).

3) After some Power ON-OFF trials LLC IC Pin no 12 RVCC pin get damaged.

Test Condition is - Input voltage 230VAC, Output voltage during properly working condition 24VDC, Output current setting with resistive load.

We are tested upto 480W using LLC Mosfets Q2, Q3 Part No :- IPB65R150CFDATMA1.

But if we are try to test with recommended as per TIDA-010015 LLC Mosfets Q2, Q3 Part No :- IPA60R120P7XKSA1 UUT Not working.

Regards,

Vivek

Hi Sir,

We are waiting for your technical guidance...

Regards,

Vivek

Hi Vivek,

What do you mean by "UUT"?

It looks your circuits works good with CFD MOS, but abnormal with P7. While our reference design show P7 should be good. Are you sure your P7 MOSFET is good?

Hi sir,

UUT :- Unit under test or Board or EUT (Equipment Under Test).

Are you sure your P7 MOSFET is good?

:- Yes, P7 MOSFET good, no issues.

Regards,

Vivek

1, Which part are you using, UCC256301?

2, can you catch the waveform of I_Lr, V_Vcc and V_Rvcc in one picture?

Hi,

1, Which part are you using, UCC256301?

- Yes. We are using UCC256301.

2, can you catch the waveform of I_Lr, V_Vcc and V_Rvcc in one picture?

- V_Vcc and V_Rvcc attached below. To catch I_Lr we don't have current probe. Any other way to catch I_Lr?

CH 1 Yellow is VCC. CH 2 Green is RVCC.

Regards,

Vivek

Hi Sir,

We are waiting for your technical guidance...

Regards,

Vivek

Hi Vivek,

The waveform you attached is good, I haven't seen any problem in it. Current waveform canbe tested by an current transformer, and suggest you include the 'sw'  waveform with diff probe for better analysis.

I recommend you to try UCC256401 in first. If it still have problem, please resubmit your question with UCC256401 tag, our product line will help you on that thread.

Hi Desheng

Thanks for the suggestions.

I was started with UCC256402A. But LLC Mosfet used IPB65R150CFDATMA1. And only LLC stage tested upto 20A.

Now can i use LLC Mosfet IPA60R120P7XKSA1??

But with UCC256402A HO & LO pulses around 34 present.. It is ok?? As per datasheet 16 required.

Regards,

Vivek

hi Vivek,

It looks your switching freq is very high, is it?

and, as your llc works well with CFD mosfet, why not keep using it? 

Hi,

We are looking IPB65R150CFDATMA1 but there are no stock and Not recommended for new designs mentioned.

And there are now dependency because of not working with recommended mosfet and same alternate not available.

What are the reasons of board not working with IPA60R120P7XKSA1 ??

Regards,

Vivek

It should be workable. Have you check the UCC256402 with IPA60R120P7XKSA1?

Have you check the UCC256402 with IPA60R120P7XKSA1? :- I have checked the UCC256402A with IPA60R120P7XKSA1. But same issue behaviour observed. Now we are finalise for our design UCC256402A.

Compared this two MOSFET, I think you can try to parallel an 100pF high voltage cap to the IPA60R120P7XKSA1. 

Ok. I will check and let you know.

And, you can try to increase the Isens resistor value. This may enlarge the current signal to avoid some mis action.

Ok. Thanks for the informations.

Can you help me for output feedback compensation. As per suggested compensation values if suddenly applied 100VAC to 200VAC with 10Amp (Half Load) board goes in hiccup mode. May be due to transient response (not confirm).

Any design calculator for the compensation values?? 

Hi vivek,

It seems your circuits works with the IPA60R120P7XKSA1, can put your finial solution in this thread. This will help the following pepole for reference. Thanks!

For the hiccup problem, I think it should triggered OVP by some reason, we need to see the waveform of bias winding, and output voltage.

And, I suggest you initiate a new E2e thread with details, it will be easier to followup as this is another new issue.