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BQ51050B Design Based On TIDA-00329 Not Working

Matt Wiebelhaus
Prodigy 30 points
Other Parts Discussed in Thread: BQ51050B, BQ51013B

I have designed a breakout board to determine whether the BQ51050B will work appropriately for a wearable device I am developing. The design is based off of TIDA-00329 and uses the same resistor and capacitor values, the difference being the component layout and component sizes. Additionally I have both the TDK WR222230-26M8-G and Wϋrth 760308101303 as indicated by the TIDA-00329 Test Report.

I had the boards fabricated and I populated them. Testing with both coils, connected via a breadboard, and also soldered directly to the PCB pads, I cannot get the board to initiate charging with the generic Qi charging pad I am using. To ensure the charging pad is functional I have a pre-manufactured BQ51013B receiver module that pairs fine. I have double checked for solder bridges on the BQ51050B IC and also verified the values of the resistors and capacitors that were soldered on. Regardless of what I have tried I still cannot get the board to function.

Attached is a PDF of the schematic, and additionally my Eagle board (.brd) and schematic (.sch) files. I have two unpopulated PCBs I can still try to populate, but I wanted to post here first to see if any critical mistakes I may have made in the schematic or with the component layout could be identified.

6747.Breakout Schematic.pdf

  • 0
    TI__Genius 14890 points

    Matt,

    First pass of the schematic looks good.  Can you confirm the voltage ratings on the capacitors?

    What are you using to emulate the battery?  If there is no battery detected, the bq51050B will not transfer power.  In general, we use a source meter or a battery capable of the required charge current.

    Taking plots of the RECT signal will be a good indication of coupling between the systems.  RECT is the rectified voltage from the AC1/AC2 pins and can be used to determine the power making it to the system.  Also, watch the OUT pin to see if anything happens when placed on the pad.

    Regards,

    Dick

  • 0 in reply to Dick Stacey
    Prodigy 30 points

    Hi Dick,

    Thanks for the response.

    Here is a table of the capacitors and resistors that I have used to populate the board, along with their voltage and tolerance ratings. Looking back at the BOM for TIDA-00329, I noticed that some of the voltage ratings are higher than for the capacitors I am using, but I wouldn't think this would stop the board from functioning... please correct me if I am wrong. As info all traces on the PCB are 9 mills, and I have also attached my Eagle schematic and board files to this response

    Component Description Manufacturer Part Number
    CLAMP1, CLAMP2 0.47uF 10volts 10% X5R AVX 0402ZD474KAT2A
    BOOT1, BOOT2 0.01uF 16volts 10% X7R  AVX 0402YC103KAT2A
    COMM1, COMM2, FOD 0.022uF 16volts 10% X7R AVX 0402YC223KAT2A
    OUT, FOD 4.7uF 10volts 20% X5R AVX 0402ZD475MAT2A
    FOD -> GND 140ohms 50 V 1% Panasonic ERJ-2RKF1400X
    TERM -> GND 2.43Kohms 50V 1 % Panasonic ERJ-2RKF2431X
    ILIM -> FOD 3.83Kohms 50V 1% Panasonic ERJ-2RKF3831X
    TS/CTRL -> GND 10Kohms 50V 1% Panasonic ERJ-2RKF1002X
    RECT -> FOD 100Kohms 50V 1% Panasonic ERJ-2RKF1003X

    For the battery I have connected both a 500mAh and 1250mAh LiPo battery.

    I have taken the requested captures of the RECT signal and attached pictures of them to this post. It seems to show 100ms pulses of ~200mV peak-to-peak. The pulses occur every 660ms. When I looked at a capture of the coil placed over the transmitter and disconnected from the wireless receiver, the same timing intervals seem to occur.

    Please let me know if I can provide any more information.

    Thanks,

    Matt2376.Breakout.sch

    3264.Breakout.brd

    1. RECT Pulse Interval

    2. RECT Peak to Peak Voltage

    3. RECT Timing Interval

  • 0 in reply to Dick Stacey
    Prodigy 30 points
    Well of course after I posted my long response with the information, I doubled checked my PCB to confirm I was taking the measurements from the RECT pin. In highlighting the RECT trace I noticed that I had shorted the trace across the pads of the 0.022uF capacitor, effectively shorting RECT to GND. I removed the capacitor, cut the trace, replaced the capacitor, and now the board functions properly.

    So I guess we at least have some oscilloscope captures of what it looks like to short RECT to GND for future troubleshooting.

    If you could still take a look at the voltage ratings of the capacitors in the table I provided and see if there are any other potential issues, I would greatly appreciate it.

    Thanks,

    Matt
  • 0 in reply to Matt Wiebelhaus
    TI__Genius 14890 points

    Matt,

    Glad to hear the board is up and running.  You definitely have some capacitor voltage ratings to update.

    The CLAMP, COMM and BOOT should be rated to a minimum of 25V.  Note they are tied directly to the AC1/AC2 pins which can get quite high.  50V gets additional margin.  

    10V would be enough for OUT, but I would consider 16V.

    RECT is the rectified voltage from AC1/AC2 and I would recommend 25V there.

    Regards,

    Dick