BQ50002A: No CLK_OUT signal on BQ50002/BQ500511

Madeleine Roche

Part Number: BQ50002A
Other Parts Discussed in Thread: BQ500511, BQ50002

Hello,

I have recently designed a wireless TX charger based on the BQ50002 + BQ500511 reference designs and the first version was 100% successful. The second version however has about a ~50% pass rate.

After debugging some hardware, it seems like the BQ50002 oscillator is not working because there is not CLK_OUT signal present, but on working boards it is there and at the same frequency as the PWM logic inputs. Our mode pin is low and the EN and PWM inputs are at switching frequency (I can attach oscilloscope shots later if you need more detail). Is there any reason why only half of the BQ50002s would be working? I am starting to assume this was a possible fabrication issue....reflow temp is 260C and we flowed around 240-250. I can't think of anything else at the moment....

Let me know if you have any ideas or have seen this behavior before...

Thanks!

Madeleine

over 6 years ago

0 Bill Johns over 6 years ago

TI__Guru 65716 points

I have not seen this problem before.
Do you have any scope captures of coil voltage?

0 Madeleine Roche over 6 years ago in reply to Bill Johns

Prodigy 100 points

Hey,

Thanks for the reply. We found out from the assembly house that the boards were reflowed at 260C +/- 3C, so it is possible that half of the ICs were reflowed at too high temperature. We are going to replace the bad ones with new ones and see if that was the issue. I will let you know.

It seems like the internal oscillator was affected the most in the BQ50002, do you know what kind of oscillator is in the chip? RC, XO?

Thanks!

Maddy

0 Bill Johns over 6 years ago in reply to Madeleine Roche

TI__Guru 65716 points

Thanks for the update, checking on oscillator info.

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BQ50002A: No CLK_OUT signal on BQ50002/BQ500511