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LM5146-Q1-EVM12V: Soft Start External Control from Micro-controller using J2 Pins on EVM

Kartavya Agarwal
Intellectual 500 points
Part Number: LM5146-Q1-EVM12V

Hi,

I want to enable a soft start to the EVM output voltage and not a hard start directly to 12V. The user guide is this:

www.ti.com/.../snvu591.pdf

How can I do this while using an external MCU (MSP432 Launchpad) and J2 header on the EVM. Can I use the SS pin on J2 header in any way?

Also, how can I use the TRIm pin on the J2 header to det the otput votlage from an external MCU (MSP432 Launchpad)?

  • +1
    TI__Mastermind 49587 points

    Hi Kartavya,

    The TRIM pin is just to adjust the output voltage by injecting a current into FB. It will be equal to the FB voltage of 0.8V in steady state (with no external voltage applied).

    You can use the EN/UVLO pin to enable or disable the output voltage. There will be a soft-start upon enable. Just use a pulldown FET on EN (at header J2 on the EVM) and release this when startup is required. See the datasheet for more detail. Also, Figure 8 in the EVM user's guide shows the ENABLE ON waveforms with Vout soft-start time of ~3ms.

    Regards,

    Tim