BQ51013: Circuit cycles - does not give a steady output

Adrian Wells

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

over 4 years ago

0 Adrian Wells over 4 years ago

Prodigy 90 points

Sorry, Please find PDF version attached

Regards

Adrian

charge.pdf

0 Bill Johns over 4 years ago in reply to Adrian Wells

TI__Guru 65706 points

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.

0 Adrian Wells over 4 years ago in reply to Bill Johns

Prodigy 90 points

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.

0 Adrian Wells over 4 years ago in reply to Adrian Wells

Prodigy 90 points

Hi again Bill,

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

Kind regards

0 Bill Johns over 4 years ago in reply to Adrian Wells

TI__Guru 65706 points

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

0 Adrian Wells over 4 years ago in reply to Bill Johns

Prodigy 90 points

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

0 Bill Johns over 4 years ago in reply to Adrian Wells

TI__Guru 65706 points

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.

0 Adrian Wells over 4 years ago in reply to Bill Johns

Prodigy 90 points

Thank you Bll, that makes sense.

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

Regards

Power management

Power management forum

BQ51013: Circuit cycles - does not give a steady output