This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ51003: BQ51003

Part Number: BQ51003
Other Parts Discussed in Thread: BQ500212A, BQ50002

Hello TI support. I have a BQ51003 receiver, which failed on WPC´s Difference:
Transmitted - Received power = 1.6 - 1.3 =0.35 W. Limit = 0.3 W. 
Using default resistors Ros = 20K, Rfod=196, Rlim = 330 Ohm. Current load is 0.3A through charge IC  to the LiION cell.
RX coil is 27*31mm, 2.5 Watt. 0.5 Ohm. 12 uH, with aluminium plate 3.5 mm away from coil.
So I need to calibrate Rfod and Ros, which demands Ref. transmitter++,  as stipulated in SLUA731.
Is there any rule of thumb for changing Ros and Rfod percentages versus increasing Received power info to transmitter by 15 or 20 %?
Or to put it in an other way: Is there any tranfer factors between these values and the Received power value to transmitter?

  • I mean, something more substantial, than these bullets? :
    • Note that Ros is adjusting the Curve Offset and the RFOD is adjusting the Curve Slope.
    • Increasing Ros increases the PLoss offset in the positive direction and increasing RFOD, makes the curve slope negative. See Figure 15.

    Thank you. /Peter

  • Hello

    Do you require Qi certification for your product , very accurate FOD cal is required?

    The AVID FOD Transmitter is best but availability is limited.  A rough FOD Cal can be done using a TI transmitter EVM (BQ500212A) or similar that will report received power (sent by RX).

  • Hi again. None of the mentioned TI transmitters are available: bq500212A bqTESLA Wireless Power TX EVM, nor bq50002 Wireless Power TX EVM, nor AVID FOD Transmitter.
    So we tried several combinations af Rfod and Ros at certification lab and found a pair which passed. A faster was the easiest trail and error way, compared to "FODCalibration" proposed by TI.
    Result: RFOD = 240 Ohm, ROS = 75K. Pass.
    But not much wiser than from the beginning, but now understand that the Rx power level replied back and compared in the reference transmitter, is a measure taken all losses into account for this particular design, so the foreign objects can be detected and Friendly object does not interfere in this FOD-decision. 
    Br. Peter