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Original question:

BQ25710: BQ25710 no charge current

BQ25710EVM-017: BQ25710EVM-017

saravanan krishnan`
Prodigy 140 points
Part Number: BQ25710EVM-017
Other Parts Discussed in Thread: BQ25710, CSD25402Q3A

Hi Team,

We are following the same design from BQ25710 EVM.What is the max  body diode current can  Q7 CSD25402Q3A handle?. My load capacitor ia round 220uF When  I am powering Up from battery only do  the Q7 BATFET can get damage or not  .If so pls suggest any solution for the same.

Regards,

K.Saravanan

  • 0
    TI__Mastermind 37890 points

    Hello K. Saravanan,

    Thanks for your interest in TI FETs. In theory, the body diode should have the same max current as the drain current of the FET. However, it is power limited and you can calculate the max body diode current as shown in the application brief at the link below. Is the current continuous or a one time pulse to charge up the capacitance on Vsys? Please review the application brief and let me know if you need further assistance

    https://www.ti.com/lit/pdf/SNVAA86

    Best Regards,

    John Wallace

    TI FET Applications

  • 0 in reply to John Wallace1
    Prodigy 140 points

    Hi John,

    I am  asking about one time pulse current to charge up the capactiance on VYS in our case around 220uF.

  • 0 in reply to saravanan krishnan`
    TI__Mastermind 37890 points

    Hi Saravanan,

    I don't see any thing to limit the current thru the FET body diode other than the board resistance and current sense resistor. Have you captured any waveforms showing pulse of charging current? The max continuous current calculation using typical RθJA = 45°C/W is as follows:

    PDIS = (TJmax - Tamb)/RθJA = (150°C - 25°C)/45°C/W = 2.8W

    ISD = PDIS/VSD = 2.8W/0.8V = 3.5A

    The pulsed current capability will be higher depending on the pulse width.

    Best Regards,

    John

  • 0 in reply to John Wallace1
    Prodigy 140 points

    Hi John,

    We are in schematic design phase only so didnt capture any waveform. I  need how much pulse current ISM  
    Example part no : Si7629DN given pulse diode current i need similar data for CSD25402Q3A

  • 0 in reply to saravanan krishnan`
    TI__Mastermind 37890 points

    Hi Saravanan,

    I reviewed the Si7629DN datasheet and the pulse diode current (-80A) is the same as the pulsed drain current (-80A). Using the same logic, then the pulsed diode forward current for the CSD25402Q3A should be -148A. Similarly, the package limited diode current should be -35A for the TI device. Let me know if you have additional questions.

    Thanks,

    John