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BQ501210 Datasheet Application Curves Page 21--RE: BQ51025EVM-649: About BQ51025EVM-649 Application Question

Kuo Duke
Expert 2040 points
Other Parts Discussed in Thread: BQ501210

Hi Bill,

May I know bq501210 operate princple about datasheet (p.21) Application Curves ? please help us to recomment it.

Why At part 1 Load and VRAIL Voltage linearly curve looks more vary ?
Why At part 2 VRAIL Voltage drop less than part 1?
At part 3 VRAIL Voltage proportional and linearly curve looks smooth.

Regards,

Duke

  • 0
    TI__Guru* 75656 points
    The variation is due to different performance of the receivers. Things such as coils, tuning, sync rectifier behavior, output voltage and others. Also the receiver feature "Dynamic Rectifier Control", will adjust the RECT voltage (in receiver) higher at light load. This will distort the output power appearance.

    The receiver will set operating point of the TX to meet requirement of voltage at Rect, it is a slave to the receiver.

    The bq501210 will adjust Rail voltage using a buck converter to change the operating point while H-bridge operates at fixed frequency and duty cycle.
  • 0 in reply to Bill Johns
    Expert 2040 points

    Hi Bill,

    1. May I know different about V_SENSE & RAIL?
    2. Why need two feedback loop? Why we cannot use V_SENSE loop control Buck regulate for transmitter voltage and FB voltage?
    3. May I know internal  I_SENSE reference voltage of bq501210? We can depandes on internal voltage to modify shunt resistor?
    4. Compare single and two stage FB WPC. Do you comment bq501210 have benefit?  (without Buck convertor)

    Regards,

    Duke

  • 0 in reply to Kuo Duke
    TI__Guru* 75656 points
    1. May I know different about V_SENSE & RAIL?---Rail + / - are use for regulation of the Rail Buck converter. V_SENSE is used for FOD, measure of voltage going to the bridge. FOD ckt will use voltage and current to H-Bridge for input power measurement.
    2. Why need two feedback loop? Why we cannot use V_SENSE loop control Buck regulate for transmitter voltage and FB voltage?---Only RAIL is a feedback loop. V_SENSE is input to the FOD measurement ckt.
    3. May I know internal I_SENSE reference voltage of bq501210? We can depandes on internal voltage to modify shunt resistor?---This circuit is part of the FOD measurements feature and should not be modified.
    4. Compare single and two stage FB WPC. Do you comment bq501210 have benefit? (without Buck convertor)-----The bq501210 is a Fixed freq rail control that will have better performance at high output power. At lower power the variable freg designs have worked well.
  • 0 in reply to Bill Johns
    Expert 2040 points

    Hi Bill,

    May I know bq501210 can support fast charger adapter Vbus20V? our adapter can support 20VDC.

    1. 5-V input supplies are aimed to negotiate to HVDCP voltages of 9 V or 12 V which enables Fast Charging of capable receivers.

    2. So, we try remove R38 from EVM, I think can let D+ get 3.3V level, but handshake fail.

    3. if bq501210 get 15W power delivery, input need up 15-19VDC. May I know how to modify EVM?