TPS65235: Inductance calculation

Hermes Lin1

Intellectual 420 points

Part Number: TPS65235

hi sir:

our LNB loading is Max 400mA. Do we have chance to replace LN106 with small one ?

how to calculate the inductor value?

over 8 years ago

0 Vental Mao over 8 years ago

TI__Expert 5745 points

The VLNB is as the SW node of the BUCK，so the value of the L ,you can use the equation like this.

0 Zhao Ma over 8 years ago

TI__Genius 15135 points

Hi, Hermes

In application, the TPS65235-1 supplys power for LNB circuit, there will be a lot of noise signal from antenna on LNB_PWR.

LN106 and CN106 forms a LC filter which will filter these noise signal and pass cleared tone signal(22kHz).

When LN106=220uH, CN106=0.1uF, the bandwidth is 1/2*pi*(sqrt(LC))=34kHz > 22kHz tone signal, which will filter >34KHz noise signal.

Besides, I also had checked several schematic of LNB application, all of them used 220uH, so recommend to not change LN106 value.

0 Zhao Ma over 8 years ago in reply to Vental Mao

TI__Genius 15135 points

Hi, Vental

TPS65235-1 is BOOST + LDO topology, not BUCK.

The customer is asking the inductor(LN106) at LNB output, not the BOOST filter inductor (LN107).

0 Vental Mao over 8 years ago in reply to Zhao Ma

TI__Expert 5745 points

OK ， thank you very much, i learn some new knowledge

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TPS65235: Inductance calculation