• Resolved

BQ51050B: How to improve range on designs using the BQ51050b

Part Number: BQ51050B

I've been using the BQ51050b RX in a design for several months now, and I'm just not getting the range that I need. To get any boards to work, I have had to take apart our transmitter so that the RX coil is actually touching the TX coil in order to get power transfer to begin, and a fraction of the boards fabricated never even get above the UVLO to start charging. I know WPC 1.1 only supports up to 7 mm, but we're not even getting close to that. If I need more range, should I move toward the WPC 1.2 technology?

  • In reply to Brad Nelson99:

    Key areas look OK:
    1.) AD pin is grounded
    2.) 10k resistor on TS/CNT pin to disable NTC temp fault ckt
    3.) Rect and Out Caps look ok
    4.) ILimt and FOD ckt OK
    5.) Term ckt OK
    6.) Coil tuning OK --- L 26uH and C10 100nF
    7.) Comm caps increase to max of 68nF

    Other things to look at or try:
    1.) Test with a larger coil the improve coupling should show better comm performance.
    2.) What type of capacitor is C10, should be X5R or X7R, it would be good to test with COG/NPO
    3.) All caps should be X5R or X7R
    4.) Try increasing the capacitor value on Rect pin
    5.) Test the small coil with bq51050 EVM

    Best Regards,

    Bill Johns,  Applications Engineer

    Texas Instruments Inc

    Dallas, Texas

  • In reply to Bill Johns:

    Thank you for all your help. I was able to build a new board using many of these changes, and it can charge up to about 6 mm from the Tx coil.