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TPS65217: Current supplied by the SYS pin of the PMIC

Shwetha Narayan
Prodigy 240 points
Part Number: TPS65217
Other Parts Discussed in Thread: BQ24032A

HI TI team,

I have connected a type C receptacle with VBus derived from the the SYS pin ( 7,8) of the TPS65217D IC. I want to know how much current I can draw from the SYS pin.

I read in the datasheet as if the PMIC is powered from UAB, the default Iusb is 1300 mA and hence the default Isys current is 800 mA. 

Is that true?

Please clarify on the above query.

Thanks and Regards

Shwetha

  • 0
    TI__Mastermind 30310 points

    Shwetha,

    The SYS pin of TPS65217 is not an output voltage for USB: it is an unregulated supply used as the input to the DCDCx converters and some of the LDOx regulators.

    If you are running on battery power, for example, VSYS = VBAT - Rds,on which has a max value of ~4.2V and is not suitable to provide USB power to any other system.

    Please reconsider your selection and provide a block diagram of your intended application so I can provide further assistance.

  • 0 in reply to Brian Berner
    Prodigy 240 points

    Hi Brian,

    Thanks for the reply. We are powering the device with USB and not with the battery. We are not at all using the battery in our system.

    But on the other end, we have a type C connector and we are powering that with the VSYS voltage.

    If his is not suitable, the how can we power the device?

    Regards

    Shwetha

  • 0 in reply to Shwetha Narayan
    TI__Mastermind 30310 points

    Shwetha,

    VSYS is the output of the PowerPath, similar to how OUT is the system power supply in the BQ24032A stand-alone charger.

    There are 2 separate blocks within the TPS65217 PMIC:

    1. Battery Charger with Power Path
    2. Power Management for processor (DCDC & LDO regulators, load switches)

    In the Battery Charger block of the device, AC & USB are always inputs, BAT is input or output, and SYS is always output.

    The connection from the Battery Charger block to the Power Management block of the device is SYS, which is an output from the Battery Charger and it connects to the VIN_DCDCx, VINLDO, and LSx_IN power inputs on the Power Management block of the device.

    In theory, SYS could be used to supply power to something other than the Power Management block, but keep in mind it is an un-regulated output (VSYS ≈

    VAC or VAC ≈ VUSB or VSYS ≈ VBAT, minus Rds,on of the respective load switch) and that some of the current out of VSYS is used to power the DCDCx & LDOx regulators and Load Switches, so the full output current capacity of VSYS cannot be used to power the rest of your system.

    I hope this is clear and you understand the operation of the TPS65217 device better so that you can use it effectively in your system.