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BQ25618E: Ship mode when VIN present

Maxime GUILLOT
Prodigy 190 points
Part Number: BQ25618E

Hello team,

I would like to use the Bq25618e on a custom design. 
I would like to use ship mode functionality and Qon push button to power off/on my device. 
I do not see any issue when VIN not present and Vbat present: Host send ship mode command by I2c -> Device turn BATFET OFF ->VSYS is power down->held QON low-> Device restart. Right?

But when VIN present (USB cable plugged), and the user want to power off the device, I was wondering if:

- MCU send ship mode command by i2c, does it turn off BATFET and RBFET and then VSYS is power down?

- MCU send ship mode command AND Hiz command to disable buck then does it turn off VSYS? Does pulling QON low restarting the BATFET and then VSYS in order to power up my device?

- if no, is there any other solution to power off and power on my device when USB is plugged?

Thank you

  • 0
    TI__Mastermind 40375 points

    Hello,

    If you have the input applied, you can set bit 4 of REG0x07 BATFET_RST_WVBUS. Then you can disable the BATFET. The SYS rail will still be powered up but the charge current will stop.

    If you have the input applied and disable the BATFET and then enable HIZ, the SYS rail will go down because HIZ is enabled. You can still talk to the device. Pulling QON low for T_SHIPMODE will cause the BATFET to turn on and power SYS. However, because the part is still in HIZ, the buck converter does not switch and no input current is taken from the input.

    Please read Section 9.3.6.3 for more information about system power reset, quoted here:

    "BATFET full system reset functions either with or without adapter present. If BATFET_RST_WVBUS = 1, the system reset function starts after tQON_RST when QON pin is pushed to LOW. Once the reset process starts, the device first goes into HIZ mode to turn off the converter, and then power cycles BATFET. If BATFET_RST_WVBUS = 0, the system reset function does not start until tQON_RST after QON pin is pushed to LOW and adapter is removed. After BATFET full system reset is complete, the device will power up again if EN_HIZ is not set to 1 before the system reset."

    Regards,

    Mike Emanuel

  • 0 in reply to Michael Emanuel35
    Prodigy 190 points

    Hello

    I tried what you said.

    - Disable BATFET with VBUS plugged -> OK

    - Put the Device in HiZ with VBUS plugged -> Buck OFF and no more VSYS

    - Pulling QON_L for T_SHIPMODE -> KO. BATFET does not turn on and SYS is not powered if VBUS present.

    Could you test on your board and see if it is normal behavior?

    Thank you

  • 0 in reply to Maxime GUILLOT
    TI__Mastermind 40375 points

    Hello,

    I repeated what I did yesterday. VBUS is present for all of this.

    • Applied 3.8 VBAT and 5.0 VBUS
    • Apply 100 mA SYS load
    • Disable watchdog timer
    • Set bit 4 of REG0x07 BATFET_RST_WVBUS
    • Disable BATFET via bit 5 of REG0X07
    • Wait 10 seconds if bit 3 of REG0x07 is checked
    • BATFET turns off, charging stops but SYS is still 3.9 V
    • Put device in HIZ
    • SYS drops
    • Pull QON low for about 1 second
    • BATFET turns on and SYS is supplied from battery

    Regards,

    Mike Emanuel

  • 0 in reply to Michael Emanuel35
    Prodigy 190 points

    Hello,

    Ok, weird. Not the same behavior on my BQ25618E

  • 0 in reply to Maxime GUILLOT
    TI__Mastermind 40375 points

    Hello,

    Can you share your schematic? What battery voltage are you using? What input voltage is being used? Please provide more information.

    Regards,

    Mike Emanuel