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SN6505B: In case of using external clock

Hirotaka Matsumoto
Guru 27525 points
Part Number: SN6505B

Hi all

Would you mind if we ask SN6505B?

<Question1>
Do you have any application in case of using external clock?
As the background of the this question, our customer would like to configure high frequency to reduce trans size with external clock.

<Question2>
If you have the formula which to calculate the value of inductance, could you give us the reference?
We would like to know relational expression between L and Fsw.

And then, the customer's condition are follows;
-Input voltage : 3.3V
-Output voltage : 3.3V
-Output current : more than 400mA 

Kind regards,

Hirotaka Matsumoto

  • 0
    TI__Expert 6955 points

    Matsumoto-san,

    1. The application of using the external clock is to allow the designer to shift EMI into a more desired spectrum. The max frequency allowed for the SN6505B is 1600kHz. One simply connects the external clock signal to the the CLK pin of the device.The SN6505B automatically detects the external clock and uses that instead of the internal clock.

    2. Unfortunately there are many variables involved for relating Fsw and the inductance of the transformer. It is not as simple as the calculations for other DC/DC power converters, like switch-mode converters, that utilize LC components. The designer will have to contact the manufacturer of the transformers in order to understand the relation between Fsw and the particular transformer desired.

    Respectfully,

    Lucas Schulte