TPS53355 / requirement parastic inductance of the board

Ryuji

Guru 20090 points

Other Parts Discussed in Thread: TPS53355

Hello,

Our customer has the problem of RF noise in their TPS53355 board.
Please let me know about the following question.

Could you please let me know the maximum parastic inductance of Lp3/Lp4 in the attached picture for achieving the following customer requirement?

Vin:12V

Vout:0.9V

Iout:15A

Fsw:970kHz

Spike noise by SW: under 10mVpp , 30mVpp

I have the schematicsm. However I can attach it to this due to that is confidential of our customer.

Thus, please contact to me directly.

asaka-r@clv.macnica.co.jp

Then I can send the schematics.

Best Regards,
Ryuji Asaka

over 10 years ago

0 JohnTucker over 10 years ago

TI__Guru**** 191445 points

I think you will find it difficult to meet those requirements. Let me see what I can find out.

0 Ryuji over 10 years ago in reply to JohnTucker

Guru 20090 points

Hello John san,

Thank you for the checking.I'm looking forward to your update.

Also , I have the cusomer schematics and boad layout.

If you need these, please let contact to the following address.

asaka-r@clv.macnica.co.jp

Best Regards,
Ryuji Asaka

0 Ryuji over 9 years ago in reply to Ryuji

Guru 20090 points

Hello John san,

Are the any updated for this post?

Best Regards,
Ryuji Asaka

0 JohnTucker over 9 years ago in reply to Ryuji

TI__Guru**** 191445 points

I have passed this on to the BU for support. I'll let you know.

0 Benyam over 9 years ago in reply to JohnTucker

TI__Intellectual 970 points

hi John and Ryuji,

ESL value is rarely specified by capacitor manufacturers and you should contact the manufacturer to determine the ESL specifications for the capacitors you are considering to use. When considering ESL, also include the ESL of the PCB traces that interconnect the capacitor with the other components.

Best Regards

0 Ryuji over 9 years ago in reply to Benyam

Guru 20090 points

Hello Benny san,

Thank you for the reply.
I understood that we should contact to manufacturo for getting capacitor's ESL.
I would like to know that maximum ESL value for achieving the following requirement.
There is no data of parasitic inductance , capacitance of iFET.
Thus, May I get that ESL data by simulation ?

<Customer Requirement>
Vin:12V
Vout:0.9V
Iout:15A
Fsw:970kHz
Spike noise by SW: under 10mVpp , 30mVpp

If we can't get these data, please let me know.
Then I will inform it to our customer.

Best Regards,
Ryuji Asaka

0 JohnTucker over 9 years ago in reply to Ryuji

TI__Guru**** 191445 points

Just curious, is the spec 10 mV or 30 mV? I think your beat bet is going to be with a snubber. If you consider 4 nsec rise time and 30 mV, then that is 8 pH inductance. You are not going to achieve that in any case. the best you can hope for is a few nH stray inductance. You will need to slow down the rise time.

0 Ryuji over 9 years ago in reply to JohnTucker

Guru 20090 points

Hello John san,

Yes, 10mV or 30mV. Our customer ASIC is very sensitive.
Thus our customer request these RF noise voltage.
I understood that we need few nH indectance and we need to slow down the reise time .

Best Regards,
Ryuji Asaka

0 Benyam over 9 years ago in reply to Ryuji

TI__Intellectual 970 points

hello, Ryuji,

Sorry, i dont have any ESL data that i can share with you.

Power management

Power management forum

TPS53355 / requirement parastic inductance of the board