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TPS1663: About selection of OUTPUT DIODE

Masanori Yachi
Prodigy 150 points
Part Number: TPS1663

Hello experts,

About the output side diode in Figure 38 of the DataSheet.
What kind of SCHOTTKY DIODE should I select when VOUT = 24V / 6A?
How should we consider the selection of DIODE?

Thanks and best regards,

Masanori Yachi

  • 0
    TI__Guru** 105361 points

    Hi Masanori Yachi,

    Due to output inductance, there will be negative voltage spikes generated at the output of eFuse during transient conditions like fast turn off. A schottky diode at the output is required to clamp –ve over voltages at OUT pin. The Schottky diode used at the output should have,

    1. A DC blocking  voltage rating much higher than the Vinmax
    2. Non-Repetitive Peak Surge Current rating > Fast trip current threshold

    For TPS1663, the fast trip current threshold is 2*current limit threshold. For 6A, it will be 12A.

    Please use equivalent Schottky diode part as used in TPS1663 EVM

    Best Regards, Rakesh

  • 0 in reply to Rakesh
    Prodigy 150 points

    Hi Rakesh,

    When I was checking past threads, there was a title "TVS and schottky diode". The contents are as follows.
    -------------------------------------------------- -------------------------------------------------- ------------
    Aug 28, 2019 5:54 AM
    Hello T Kishi,

    Diode D4 is used to prevent negative voltage when the device the turns-off the internal FET in case of overload or short circuit on output. Under normal operating conditions, the diode will not be conducting. For 24V / 4A output, 60V / 2A diode can be used at output (as D4).

    For input TVS diode, a unidirectional TVS would be required. The specifications of TVS are decided by the transients on input supply voltage.

    Please click "This resolved my issue" button if this post answers your question

    -Lokesh
    -------------------------------------------------- -------------------------------------------------- ------------
    This is inconsistent with past posts, but which is the correct answer?
    Fast trip current threshold is 2 * current limit threshold
    Fast trip current threshold is 1/2 * current limit threshold

    Thanks and best regards,

    Masanori Yachi

  • 0 in reply to Masanori Yachi
    TI__Guru** 105361 points

    Hi Masanori Yachi,

    I am mentioning about the Non-Repetitive Peak Surge Current rating of the diode. A typical 2A diode(for example b260-13-F) will have at least 20x times the Non-Repetitive Peak Surge Current rating.

    Best Regards, Rakesh

  • 0 in reply to Rakesh
    Prodigy 150 points

    Hi Rakesh,

    Thank you for answering

    I would like to implement CMS15 (VRRM = 60V IF = 3.0A IFSM = 60A) in the 24V / 6A circuit. Is this okay?

    Thanks and best regards,

    Masanori Yachi

  • 0 in reply to Masanori Yachi
    TI__Guru** 105361 points

    Hi Masanori Yachi,

    CMS15 is suitable for your use case.

    Best Regards, Rakesh