TPS543B20: About SW pin ringing

Tsukui Yusuke

Guru 21930 points

Part Number: TPS543B20
Other Parts Discussed in Thread: TPS543C20

Hi,

Could you tell me about TPS543B20 sw pin ringing?
Please check the attached document.

About TPS543B20 SW pin ringing level.pdf

When the input voltage is high (15V),the ringing becomes small.
When the input voltage is low (10V to 14V), the ringing increases.

Please tell me the reason.
Does TPS543B20 have mode switching function depending on input voltage level?

Best Regards,
Yusuke/Japan Disty

over 6 years ago

0 JohnTucker over 6 years ago

TI__Guru**** 191445 points

Yusuke,

Actually there is special circuitry internal to TPS543B20. See details below. The ringing is dependent on current. What is the load during your test?

0 Tsukui Yusuke over 6 years ago in reply to JohnTucker

Guru 21930 points

John-san,

Thank you for your reply.
Output current conditions of all of the waveform is 7A.
When the input voltage condition is high, I think that the ringing becomes large.
However, when it is 15 V or more, ringing becomes small.
Customer wants this reason.

Could you give me your advice?

Best Regards,
Yusuke/Japan Disty

0 JohnTucker over 6 years ago in reply to Tsukui Yusuke

TI__Guru**** 191445 points

Yusuke,
I'll see what I can find out. It may be a couple days.

0 Tsukui Yusuke over 6 years ago in reply to JohnTucker

Guru 21930 points

John-san,

Thank you for you response and support.
I look forward to hearing from you.

Would you be able to confirm the following?
・Would this be a normal behavior for this device ?
・If it is, why would this happen ?

Best Regards,
Yusuke / Japan Disty

Best Regards,
Yusuke/Japan Disty

0 JohnTucker over 6 years ago in reply to Tsukui Yusuke

TI__Guru**** 191445 points

Yusuke,

Actually there is some circuitry internal to TPS543B20. Both TPS543C20/B20 have the switch mode to lower the switching ringing at Vin higher than 14.5V.

0 Tsukui Yusuke over 6 years ago in reply to JohnTucker

Guru 21930 points

John-san,

Thank you for your kind support.
" TPS543C20/B20 have the switch mode to lower the switching ringing at Vin higher than 14.5V."
→Please tell me how to implement this function.
　 When Vin higher than 14.5V, Does TPS543B20 control the FET on slew rate?
Could you tell me more detail about this function?

Best Regards,
Yusuke/Japan Disty

0 JohnTucker over 6 years ago in reply to Tsukui Yusuke

TI__Guru**** 191445 points

Yusuke,

Let me see if I can get more details. It may take a day.

0 Tsukui Yusuke over 6 years ago in reply to JohnTucker

Guru 21930 points

John-san,

Thank you for you response and support.
I look forward to hearing from you.

Best Regards,
Yusuke/Japan Disty

0 JohnTucker over 5 years ago in reply to Tsukui Yusuke

TI__Guru**** 191445 points

Yusuke,

When the Vin is higher than ~14.5V, the internal logic will change the gate driver strength to weak option to ensure the SW ringing lower.
Please see similar idea implantation in this blog that Kit Nguyen wrote.
e2e.ti.com/.../the-effects-of-gate-driver-strength-in-synchronous-buck-converters

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TPS543B20: About SW pin ringing