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bq51013B: How to perform testing in production without using a coil?

Burkhard Merg
Prodigy 50 points
Other Parts Discussed in Thread: BQ51013B, BQ51013

Since in our design only a few parts are testable with a passive ICT, we have to define a functional test. Is there a chance to test an assembled PCB without connecting a receiver coil  and using a wireless transmitter device?

  • 0
    TI__Genius 14890 points

    Burkhard,

    What sort of testing do you need to do on the bq51013B circuitry?

    If you are interested in testing the circuitry to be powered by the bq51013B, you can apply 5V to OUT.  The would be no issues with the bq51013B.

    If you want to test the bq51013B, you could consider putting a sine wave on the AC1/AC2 pins similar to what would occur with the RX coil on the Transmitter.  A simple function generator may not have enough power to get what you're looking for, this may need to be amplified.  

    Since the typical "ping" frequency is 175kHz, that is a safe place to start.

    Regards,

    Dick

  • 0
    Prodigy 50 points
    Hi Dick,
    thanks a lot for your reply. Your hints for testing the circuitry are helpful.

    Three kind of tests are planned at EMS on PCB level:
    1. AOI
    2. ICT (passive)
    3. Functional Test
    The reason and scope of testing is a risk driven decision and shall ensure, that unacceptable risks caused by production issues (e.g. wrong assembly) must be avoided. Furthermore testing shall ensure, that all functions of the target medical device are proven.
    Some of the passive parts around the bq51013 are testable by the ICT. Since our PCB design is very compact and PCB space is limited, not all ICs and Rs are accessible by test points. All capacitors at COMx, CLMPx, BOOTx TS/CTRL and the RLIM at ILIM are affected.
    Is there a chance to detect wrong assembly without using an ICT?
    The following tests are envisaged:
    a) check the function of the power transfer by applying a sine wave on AC1/AC2 pins
    b) check the Overall Efficiency of the power transfer (to recognize a mismatched oscillator)
    c) check the current Limit by connecting a high load at the Output

    Regards
    Burkhard
  • 0 in reply to Burkhard Merg
    TI__Genius 14890 points

    Burkhard,

    Thank you for the details.  The only way to test the full values is to run on a TX.  When you force AC1/AC2, that prevents the communication back to the TX so the COMMx capacitors cannot be tested.  The CLAMP capacitors are mainly for protection so hopefully you don't test those.  The BOOT will be tested if the OUT turns on.  RILIM can certainly be tested as you note.  TS/CTRL depends on how you are using it.  Is it a thermister circuit or simply the 10k resistor?

    As I noted on the original response, the signal you put on AC1/AC2 must be able to supply the required current.  

    Efficiency will need to be relative.  TX+RX system, the communication from the RX sets the frequency to the optimum level for best efficiency.  If you force a frequency, you may not be at the best value.  In normal operation, the Rectifier voltage (seen at the RECT pin) is the key to efficiency.  At light loads (as seen in datasheet plots) the efficiency is not as important as maintaining the ability to respond to load steps so RECT is higher than it needs to be for optimum efficiency.  At heavy loads, the communication sets the RECT voltage as close to OUT as possible to maintain the lowest loss in the RX.

    Regards,

    Dick