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bq500210 Switching Frequency

PAN-M
Mastermind 8375 points
Other Parts Discussed in Thread: BQ500210

bq500210 ES board is not work.

The switching frequency is written in the datasheet from 110KHz to 205KHz, but 60KHz is output.

ES circuit is attached. (and additional wire = 10 and 11pin 100K pull down to AGND, 20 and 26pin wire to AGND, 31pin 100K pull down to AGND, JTAGs 27,28,29,30pin 10K pull up to 3V3_VCC)

Why this board output is 60KHz?

 

  • 0
    TI__Guru 69186 points

    I suspect that the problem may be grounding or V33D / V33A filtering of the BQ device.

    Would it be possible to send layout also.

    I will contact you using the friend then conversation feature.

    Bill

  • 0 in reply to Bill Johns
    Mastermind 8375 points

    Thank you for reply.

    I got the photo file from our customer's bord.

    Regards,

    PAN-M

  • 0 in reply to PAN-M
    TI__Guru 69186 points

    Layout for bq500210 ground and V33D / V33A appear to be poor.  This will result in noise and problems with the clock freq. 

    The V33D (pin 33) filter capacitor must be very close to the device with low impedance connections.  V33D capacitor return must have a low impedance connections back to the DGND (pin 32).  This also applies to V33A (pin 34) and AGND return (pin 36).

    But also we have seen problems with 2 layer designs due the poor grounding.  A good ground plane will provide the best results and most reliable design.  The customer’s board is a 2 layer prototype with a poor ground plane.  I think they will have other problems.

    Bill

  • 0 in reply to Bill Johns
    Mastermind 8375 points

    Thank you, Bill

    I will consult to them in this suggestion.

    PAN-M