UCC21530: Synchronous Buck Converter

Neeshitha Sudhakar

Part Number: UCC21530

I'm using UCC21530 to drive a synchronous buck converter (500V to 200V). Considering the parasitic inductances and to keep the gate-source voltage below the threshold voltage level, I'm using Zener diode to provide negative bias. There is no specific guidance on choosing the current limiting resistor connected in series with the Zener. I'm using 51ohm resistor. For some reason, I'm facing convergence problem while simulating it under transient mode. It stops at 56%. Will you be able to guide me on this? I have attached screenshots of my circuit and the output.

over 4 years ago

0 Zachary Wellen over 4 years ago

TI__Prodigy 650 points

Hi Neeshitha,

Thank you for your question. I work on the applications team in the high power drivers group.

Sometimes there is some high frequency noise in these simulations that can cause the convergence error. You should start by altering the TR minimum Time Step parameter to a larger value, around 1ps. If you still get the convergence error after changing this value, ignore it and let the simulation continue. It may take longer to simulate in this case.

If this answered your question, could you please press the green button? If not, feel free to ask more questions.

Thank you and best regards,
Zachary

0 Neeshitha Sudhakar over 4 years ago in reply to Zachary Wellen

Prodigy 80 points

Hi Zachary,

The TR minimum time set-up was at 10ps and even after ignoring the convergence issue it stops at 56%. I tried increasing the TR minimum time setup as you suggested. But its very slow compared to the previous one. Do I have to change any other parameter. I'm simulating it on TINA. Or does it have to do anything with circuit itself?

Thank you.

Neeshitha Sudhakar.

0 Zachary Wellen over 4 years ago in reply to Neeshitha Sudhakar

TI__Prodigy 650 points

Hi Neeshitha,

Could you send me the TINA files so I can take a look at them?

Thank you and best regards,

Zachary Wellen

0 Neeshitha Sudhakar over 4 years ago in reply to Zachary Wellen

Prodigy 80 points

Hi Zachary,

Sure, I'll upload it here.

Thank you.

Neeshitha SudhakarUCC21530_rev_3.TSC

0 Zachary Wellen over 4 years ago in reply to Neeshitha Sudhakar

TI__Prodigy 650 points

Hi Neeshitha,

I increased the minimum conductance and got the model to simulate.

Here is the updated file: UCC21530_rev_4.TSC

If this answered your question, could you please press the green button? If not, feel free to ask more questions.

Thank you and best regards,
Zachary

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UCC21530: Synchronous Buck Converter