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September 20, 2025
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EVLSTGAP3SXS-H circuit question

Hi,
Im analyzing the circuit of the STGAP3SXS in EVLSTGAP3SXS-.
I want to ask what's the purpose of this capacitance in the soft off pin, I thought it was filtering by why does it go to the VL instead of GND_ISO
Thank you.

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    Peter BENSCH
    Peter BENSCHBest answer
    ST Technical Moderator
    September 22, 2025

    It may be confusing, but C14 at the pin SOFTOFF is in fact a filter capacitor. However, in terms of AC, it is also connected to GNDISO_H via C9/C10, which are more than 30,000 times larger than C14, so that it performs its filter function in exactly the same way.

    However, the DC reference point for the SOFTOFF output is VL, as can be clearly seen in section 6.5 of the data sheet, for example.

    Hope that answers your question?

    Regards
    /Peter

    In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.
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    1 reply

    Peter BENSCH
    Peter BENSCHBest answer
    ST Technical Moderator
    September 22, 2025

    It may be confusing, but C14 at the pin SOFTOFF is in fact a filter capacitor. However, in terms of AC, it is also connected to GNDISO_H via C9/C10, which are more than 30,000 times larger than C14, so that it performs its filter function in exactly the same way.

    However, the DC reference point for the SOFTOFF output is VL, as can be clearly seen in section 6.5 of the data sheet, for example.

    Hope that answers your question?

    Regards
    /Peter

    In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.
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