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TUSB8020B-Q1: External pull up for BATEN1 and BATEN2

Yen Nee Lee
Prodigy 120 points
Part Number: TUSB8020B-Q1

Hi, 

Would like to confirm on few matters:

1. On pin4 (BATEN1) and pin 6 (BATEN2), do they output high when there is VBUS input to the voltage divider at pin 9?

2. If downstream port 1 does not require VBUS and downstream port 2 requires VBUS to power up USB device (but not battery charging), do the pin4 and pin 6 still require the 4.7kOhm pull up to 3.3V?

3. For above configuration, can i leave pin 36 (FULLPWRMGMTz) open as the upstream port is SS USB capable port?

Thanks.

  • 0
    TI__Guru 60870 points

    Hi,

    1. The PWRCTLx/BATENx are asserted when the USB host controller enables power on the downstream ports of the hub or when required to by the USB specification.  Also, if battery charging is enabled, when the USB host is disconnected, the hub will toggle power on the downstream ports and then re-enable it for charging.

    2. The pullups on PWRCTLx/BATENx are only needed to enable battery charging, they are not required for normal port operation.

    3. FULLPWRMGMTz should be pulled low since port power control is implemented in the system.

    Regards,

    JMMN

  • 0 in reply to JMMN
    Prodigy 120 points

    Hi,

    In the design we intend to use the default IC configuration without I2C/SMBUSz communication to host (pin 2 and pin 3 are left unconnected).

    Can it be configured via the USB upstream port? Or the only way to assert the BATEN2 pin high is by having an external 4.7kOhm pull up on that pin?

    Below is my current configuration, please advise if you see any concern:

     - pin22 (SMBUSZ_SS_DN2)unconnected

    - pin 21 (PWRCTL_POL_SS_DN1) pulled low

    - pin 35 (GANGED_SMBA2_HS_UP) pulled low

    - pin 36 (FullPWRMGMTZ_SMBA1_SS_UP) pulled low

    Thanks.

  • 0 in reply to Yen Nee Lee
    TI__Guru 60870 points

    When battery charging is not enabled, the PWRCTLx_BATENx outptus will be asserted when the hub is connected to a host and enumerated.

    Regards,

    JMMN

  • 0 in reply to JMMN
    Prodigy 120 points

    Hi,

    Just to confirm my understanding, 

    When the hub is enumerated by the host, the hub's PWRCTLx_BATENx will be asserted high regardless whether there is any connection at the downstream port. I do not need the external pull up to BATEN pin and no I2C reconfiguration/SMBUS is required.

    Thanks!

  • +1 in reply to Yen Nee Lee
    TI__Guru 60870 points

    Yes, that is correct.