TPS55340: tps55340

Hojin Sung

Prodigy 110 points

Part Number: TPS55340

Hi, guys

I can't find what does this capacitor work in datasheets.

I know another one would charge energy and give back to inductor during turn off

However, I have no idea of this capacitor, why don't use just one of 110uF (100+10)uF??

Please let me know.

Thanks a lot! have a nice day!

over 4 years ago

0 Zack Liu over 4 years ago

TI__Mastermind 34201 points

Hi Hojin,

The input capacitor C2 in required to meet ripple and the transient requirements. You can take a look at page 17 in datasheet.

0 Hojin Sung over 4 years ago in reply to Zack Liu

TI__Prodigy 110 points

Dear, Zack Liu

Thanks for replying my question about C2.

I think C2 is same feature as C7.

1. I read the paper, howerver still I can't understand why don't use just one capacitor(100+10uF).

2. Also I need to test changing switching frequency, how to control the Switch frequency in TINA?

Regards,

Hojin

0 Zack Liu over 4 years ago in reply to Hojin Sung

TI__Mastermind 34201 points

Hi Hojin,

1. What do you mean one capacitor(100+10uf)? The schematic you shown uses one 10uF cap + one 100nF cap.

2. By changing resistor R4 ( connecting to FREQ pin), the switching frequency could be adjusted between 100kHz to 1.2MHz. Place another node to see SW pin waveform. For me details, please see part 7.3.2 in datasheet.

0 Hojin Sung over 4 years ago in reply to Zack Liu

TI__Prodigy 110 points

Hi, Zack

I solve many issues thanks to you.

but Question.1 It was a typo.

So, what is the benefits for using parallel capacitor not using one capacitor(100nF+10uF).

Regards,

Hojin

0 Zack Liu over 4 years ago in reply to Hojin Sung

TI__Mastermind 34201 points

Hi Hojin,

Smaller value ceramic capacitor has less ESL and ESR than 10uF cap, which is good for absorbing high frequency noise.

Place the 100nF cap close to IC Vin pin.

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TPS55340: tps55340