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TPS54541: Acceptable ripple of input voltage

Johannes Hofmann
Intellectual 270 points
Other Parts Discussed in Thread: TPS54541

Hello Community,

We are using this buck converter in an application with a power demand of 15W peak and i have to find out which maximum ripple of the input voltage is acceptable.

The input voltage ranges from 7 to 42VDC and the input stage of the converter has two 10µF capacitors and transient protection.

The output voltage is set to 5V.  It would be nice if you could provide me with a value or give me some hints how to calculate that by myself.

Best regards

Hannes

  • 0
    TI__Mastermind 35115 points

    Hi Hannes,

    For a minimum input capacitance for the TPS54541 I recommend using similar to what we used in our evaluation of this part. We used 2x 2.2µF ceramic capacitors which is where the 3µF decoupling recommendation in the datasheet comes from.

    In addition to meeting this minimum value, the placement and layout is important. These capacitors should be placed very close to the VIN pin and schottky diode. Also make sure to minimize any trace inductance between the input capacitors and the VIN pin as well as between the schottky diode and the SW pin.

    Best Regards,
    Anthony

  • 0 in reply to Anthony F
    Intellectual 270 points

    Hello Anthony,

    Thanks for not responding to my question at all :)

    We are writing the hardware manual now, that's why i'm asking this question. The layout is already done.

    It is important for our device to work also in an environment, where the input voltage can be heavily swinging, for example in an automotive environment, where our devices will be used (car battery).

    So for the converter to still deliver a stable output voltage of 5V, which input ripple of the supply voltage is tolerable?

    Thank you