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USB-PD-CHG-EVM-01: No "Ship Mode" because no Ship FET is populated?

Andreas Bachmann
Prodigy 50 points
Part Number: USB-PD-CHG-EVM-01
Other Parts Discussed in Thread: BQ25792EVM, TPS25750, BQ25792

I would like to test the "Ship Mode" on the USB-PD-CHG-EVM-01. In the datasheet it’s not clearly written if the Ship FET must be present. The datasheet says:

My understanding is that a Ship FET is not necessary but preferred because the leakage current is lower with a Ship FET.

So I set the registers from

reg=0x0F name=Charger Control         size=6 data=0xA2 0x85 0x40 0x00 0x01 0x16
    SDRV_CTRL             = 0
    SDRV_DLY              = 0
    SFET_PRESENT          = 0

to

reg=0x0F name=Charger Control         size=6 data=0xA2 0x85 0x45 0x00 0x01 0x96
    SDRV_CTRL             = 2
    SDRV_DLY              = 1
    SFET_PRESENT          = 1

as in the datasheet

But the system voltage doesn’t drop, so the BATFET is still on.

I checked the forum and found two interesting posts:

As I understand now, I cannot test the "Ship Mode" on the USB-PD-CHG-EVM-01 because there is no Ship FET populated?

So I need to design an own PCB to test it?

  • 0
    Prodigy 50 points

    Oh, here is a part of the schematic of the USB-PD-CHG-EVM-01:

  • +1 in reply to Andreas Bachmann
    TI__Mastermind 40455 points

    Hello,

    If you would like to test the ShipFet capability you have two options:

    1. Try out the BQ25792EVM.

    2. Make your own PCB.

    The USB-PD-CHG-EVM-01 does not support ShipFet capability. In addition, if you make a design with the TPS25750 you will have to control the ShipFet via I2C.

    Thanks,

    Mike Emanuel

    Please click "Resolved" if this answered your question.

  • 0 in reply to Michael Emanuel35
    Prodigy 50 points

    Hi Mike,

    I need to design my own PCB anyway (just the BQ25792 without the TPS25750). I just copy/paste most of the USB-PD-CHG-EVM-01 schematic, but now that I need a Ship FET I took the BAT/BATP/SDRV from the BQ25792EVM schematic.

    Part of BQ25792EVM schematic:

    Part of my own schematic:

    Part of my own PCB:

    Does that make sense?

  • 0 in reply to Andreas Bachmann
    TI__Mastermind 40455 points

    The Ship FET looks good on the schematic.

    For layout:

    1. Please make sure the smaller SYS capacitor is closer to the pin than the larger ones.

    2. Please make sure the smaller PMID capacitor is closer to the pin than the larger ones.

    3. Please make sure the smaller VBUS capacitor is closer to the pin than the larger ones.

    5. Please make sure the inductor is close to SW1 and SW2. 

    7. Please make sure the REGN capacitor is as close as possible to the IC.

    Thanks,

    Mike Emanuel

    Please click "Resolved" if this answered your question.