TIDA-01568: C2 value

Chong Yu

Intellectual 1435 points

Part Number: TIDA-01568
Other Parts Discussed in Thread: LM3881

Hi,

My customer need assistance.

I understand the relationship between the capacitor C2 and delay of LM3881.

But C2 in schematic is 10nF, in BOM is 2.2nF. Which one is correct in this reference design?

https://www.ti.com/lit/df/tidrwc0/tidrwc0.pdf

https://www.ti.com/lit/df/tidrwc4/tidrwc4.pdf

Please help. Thanks.

over 2 years ago

0 Jenson over 2 years ago

TI__Intellectual 2105 points

Hi,

Sorry for late.

Please refer to the Bom table, the design uses 2.2nf.

Jenson

0 Chong Yu over 2 years ago in reply to Jenson

TI__Intellectual 1435 points

Hi, Jenson

Thanks for the reply.

Actually this answer surprised me a little. Since I had read the design guide:

https://www.ti.com/lit/ug/tidudt4/tidudt4.pdf

On page 13, chapter 2.4.2.2, it mentioned that the capacitor is 10nF to adjust the delay to 9.6ms. The capacitor is the same as the schematic. I thought the mistake is in BOM.

I will have to ask you to review it and make sure.

It will be appreciated.

Best regards.

0 Jenson over 2 years ago in reply to Chong Yu

TI__Intellectual 2105 points

Hi,

Yes, I have checked the Reference Design Guide.The cap(C2) is use 10nf to calculate the delay.

But in the PCB and BOM, the C2 is use 2.2nf. So I think maybe the final application is changed to 10nf.

Sorry for the misunderstanding！

B.R.

Jenson

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TIDA-01568: C2 value