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bqTESLA Transmitter 19V input requirement

Ron Steen
Prodigy 30 points
Other Parts Discussed in Thread: BQ500210, BQ500110

What system system design requirement drove the WPC 19 V primary coil supply specification ? 

  • 0
    TI__Guru* 76436 points

     

    The bq500210 and bq500110 IC support the Power Transmitter design A1.  Input voltage requirements for A1 are covered in Section 3.2.1.2 "The input voltage to the half-bridge inverter is 19 +/- 1V."

    But this requirement is the voltage applied to the input to the half-bridge. If the customer would like to use a lower input voltage and boost that voltage to 19V before applying it to the half-bridge this is acceptable. Other converter options that will produce 19V are also possible. 

    Other Power Transmitter design types (B1, B2) with other input voltages are available.

    The 19-V adapter requirement comes directly from the WPC specification and is a requirement for this transmitter architecture. The primary reasons for a 19-V adapter are (1) adapters that deliver 19V and > 8 W are readily available and (2) for the typical power and voltage levels at which a WPC receiver can operate, using a 19-V adapter results in primary coil currents on the order of 0.7 to 1.5-A RMS which enables the use of relatively low cost power FETs and series resonant capacitor. Please note also that all WPC transmitters must be able to provide 5-W at the output of two pre-defined reference receivers. Since the system efficiency is typically in the range 65 – 75%, this means that to guarantee the required receiver output power the adapter for a WPC transmitter must be able deliver at least 8 W. Currently the WPC is working to develop a 5-V transmitter solution that will take advantage of the increased availability of higher power 5-V adapters used in the tablet market.

     

     

    Best Regards

    Bill

  • 0 in reply to Bill Johns
    Intellectual 575 points

    The products have maybe got 12V-19V boost converters in them.

    The standard says - voltage to the coil should be 19V (informative).

    I was a bit curious as to why it said "informative"? i take it using a boost converter and use a standard 12V power supply would still be compliant?

     

    Cheers,

    Michael.

     

  • 0 in reply to MICHAEL MACLEAN
    TI__Guru* 76436 points

    The (informative) comment refers to the statement that follows.  This statement points out near resonance voltage on capacitors can be high.

    Best Regard

    Bill