BQ4050: SMBC and SMBD issue

Cherry Zhou

Part Number: BQ4050

Hi team,

Here's an issue from the customer may need your help:

Regarding SMBC and SMBD, a typical circuit does not have parallel capacitors at both ends of the regulator, but the customer want to pass high ESD requirements.

They've added capacitors at both ends of the regulator. The question is 100pF capacitance is OK, but 100nF capacitance cannot communicate. What's the reason for that?

Could you help check this case? Thanks.

Best Regards,

Cherry

over 3 years ago

0 Shirish over 3 years ago

TI__Guru 57697 points

Hello Cherry,

Maximum capacitance including PCB and wire capacitance on each line cannot exceed 400pF per spec. Customer should use low capacitance ESD protector instead of capacitor.

0 Cherry Zhou over 3 years ago in reply to Shirish

TI__Mastermind 22235 points

Hello Shirish,

Thanks for your help. The customer would like to know where can check the spec. the each line cannot exceed 400pF, they check the bq4050 DS/EVM/TR, but didn't find that.

And you said the ' each line', dose it mean the BQ4050 32 pin?

Thanks and regards,

Cherry

0 Shirish over 3 years ago in reply to Cherry Zhou

TI__Guru 57697 points

Each line refers to SMBD and SMBC only. The higher the capacitance, the lower the reliability, so i would not recommend designing based on the maximum value even if it was specified in a document.

0 Cherry Zhou over 3 years ago in reply to Shirish

TI__Mastermind 22235 points

Hi Shirish,

Could you help provide the document you mentioned before that elaborating on the maximum value 400pF?

Thanks and regards,

Cherry

+1 Shirish over 3 years ago in reply to Cherry Zhou

TI__Guru 57697 points

Hello Cherry,

This document has that information www.ti.com/.../scpa054.pdf

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BQ4050: SMBC and SMBD issue