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BQ25798: BQ25798 HVDCP recognition

Hee Keun Park
Prodigy 40 points
Part Number: BQ25798

Tool/software:

Dear Ti members

I am inquiring about an HVDCP issue where the VBUS voltage does not go above 5V when a USB Type-C PD TA is connected to the BQ25798.

1. Test Environment
. BQ25798 with Type-C connector & FUSB303B PD IC. refer to schematic.
. Probe of Osiloscope were connected USB port of BQ25798.
. The USB cable was connected to the charger first, and the cable was connected to TA when starting the test.
. Register set as following before USB power plug-in.
offset11h : 78h
. after USB power plug-in, capture osiloscope inage and then dump register of bq25798

2. Issue
. It does not go above 5V in a TA that supports 9V.
. Type-C PD TA is not recognized properly .

3. Request
ⓐ. What register should I set to increase VBUS above 9V (for HVDCP)?
ⓑ. What do I need to do to properly recognize Type-C PD TA?
ⓒ. Can the PD Chipset (FUSB303) connected to the USB type-C connector affect the recognition of the TA by the BQ25798 IC?
     If yes, do we need to remove FUSB303B?
     To use FUSB303B together, what value should be changed to which REGISTER of BQ25798?

Thanks and Best Regards

Hee-Keun ParkTi_BQ25798 Detect_20240708.pptx

  • 0
    TI__Guru**** 165886 points

    Hi Hee-Keun,

    Type-C PD TA use the CCx lines for negotiation not D+/D- lines that were used for legacy USB ports.  You will need to add an IC that can communicate with USB-C PD CCxx lines.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 40 points

    Good Morning Jeff F.

    Thanks for your the detailed explanation.
    Page 2 of the attachment is the recognition waveform of TA that supports Legacy 9V.
    What do I need to do to transition to HVDCP 9V?
    (I set the register as shown in the data sheet, but it did not transit to 9V)

    Thanks and Best Regards

    Hee-Keun Park

  • 0 in reply to Hee Keun Park
    TI__Guru**** 165886 points

    Hi Hee Keun,

    The auto negotiation is not compatible.  The host software can perform its own negotiation by writing the D+/D- output voltages using REG0x47.  You will need to know the voltages and timing of each for the negotiation.

    Regards,

    Jeff