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BQ51013: Circuit cycles - does not give a steady output

Prodigy 90 points

Replies: 8

Views: 175

Part Number: BQ51013

Can anyone help or suggest a test regime please?

The attached PDF shows the power supply circuit of my project . The design is taken from the component data sheets with values calculated against the coil inductance Ls = 12u3H  (quoted) and Ls' = 16u5H (extrapolated from other data).

I would anticipate a steady output at [OUT] when the coil is on the charger, regardless of load. I have tested with both a 'Chinese' wireless charger and a Samsung phone charger. The results are the same.

With a LiPo (open voltage 3v73) connected at [V_BATT], or no battery connected, I see LED_3 (!CHG_1) and LED_1 (!CHG) flash on momentarily, then after a short delay, repeat.

If I connect a faulty LiPo (open voltage 2v93), I see the same as above, but in addition LED_2 (!PG) comes on momentarily after LED_1

Lipo capacity 600mAh (quoted)

charge.sch

  • Sorry, Please find PDF version attached

    Regards

    Adrian

    charge.pdf

  • In reply to Adrian Wells:

    Hello Adrian

    Seen a scope capture of the voltage at RECT pin of the  BQ51013, this is a good indication of what the unit is doing.

    Also send data sheet or link to RX coil.

    Recommend adding a 10k pull down to the AD pin to make sure it does not go into adapter mode.

    Best Regards,

    Bill Johns,  Applications Engineer

    Texas Instruments Inc

    Dallas, Texas

    For more information on Battery Charger Solutions see Link

    Search "FAQ" on E2E Forum for common questions on battery charger solutions. 

  • In reply to Bill Johns:

    Many thanks Bill,

    I'll try the pull down first - i was looking in that area, but unsure what value to try.

    I've requested coil data. I think that the manufacturer site was lacking full spec. It was chosen with size in mind.

    I'll get a scope on it if the resistor fails.

  • In reply to Adrian Wells:

    Hi again Bill,

    Just to confirm 10K between AD (pin 9) and ground

    Kind regards

    A

  • In reply to Adrian Wells:

    Just to confirm 10K between AD (pin 9) and ground----Yes

    Best Regards,

    Bill Johns,  Applications Engineer

    Texas Instruments Inc

    Dallas, Texas

    For more information on Battery Charger Solutions see Link

    Search "FAQ" on E2E Forum for common questions on battery charger solutions. 

  • In reply to Bill Johns:

    Bill,

    Apologies for the delay.

    Due to board layout, I was unable to connect to AD

    However I was able to strap !AD-EN to ground via 10K and that worked on the prototype. Great!
    For anyone else reading this, my values worked with both a cheap Chinese "Wireless charging pad" and a full-on "Samsung Fast Charge EP-PN920" Phew!

    Is there a reason why I should attach to AD rather than !AD-EN ?

    Regards

    A

  • In reply to Adrian Wells:

    HI Adrian

    Pulling down AD-EN will turn on the USB MOSFET, without power on USB the unit should not start. 

    If you have No USB power, AD floating and Wireless power applied. Then ground AD-EN and unit works.  --- Could be OUT pulling down AD input, with MOSFET on OUT and AD are connected. 

    Best Regards,

    Bill Johns,  Applications Engineer

    Texas Instruments Inc

    Dallas, Texas

    For more information on Battery Charger Solutions see Link

    Search "FAQ" on E2E Forum for common questions on battery charger solutions. 

  • In reply to Bill Johns:

    Thank you Bll, that makes sense.

    I now have 10K puling down AD and it works fine. Many thanks for your help.

    Regards

    A