BQ24780S: Mosfet voltage

switch

Part Number: BQ24780S
Other Parts Discussed in Thread: BQ24780

Tool/software:

Hi ti team，

The new project is using BQ24780 to charge a 4-cell battery. When the adapter is unplugged, it is found that the S terminal and G terminal of the MOS (QB2) always have a voltage of 18.7V. What is the reason for this?

Channel 1 is D, channel 2 is S, and channel 3 is G.

7 months ago

0 Aaron Bagger 7 months ago

TI__Prodigy 720 points

Dear user,

To further help you with this issue, I have a couple questions about your schematic.

1. What does +VADP represent?

2. What is the voltage measurement of +V_CHRG_VIN when you unplug the adapter.

Thanks,

Aaron

0 switch 7 months ago in reply to Aaron Bagger

Genius 3960 points

Hi Aaton，

1. What does +VADP represent?

The adapter inputs to +V_CHRG_VIN, then to MOS, and finally to VADP.

2. What is the voltage measurement of +V_CHRG_VIN when you unplug the adapter.

After disconnecting the adapter, the voltage at +V_CHRG_VIN is 17.9V.

0 Aaron Bagger 7 months ago in reply to switch

TI__Prodigy 720 points

Thank you for this information, I'll be looking more into this.

0 Aaron Bagger 7 months ago in reply to switch

TI__Prodigy 720 points

Dear user,

I have a couple follow up questions,

1. Can you provide a waveform of VIN, ACDET, and ACOK when you unplug the adapter?

2. I see on your schematic you have VADP, +V_CHRG_VIN, and +VCHRG_PWR. Can you confirm which one of these supplies your adapter power and what sources the 17.9V at +V_CHRG_VIN?

Best regards,

Aaron

0 Aaron Bagger 6 months ago in reply to Aaron Bagger

TI__Prodigy 720 points

Dear user,

I wanted to follow up with you regarding this issue. Does this problem still persist?

Best Regards,

Aaron

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BQ24780S: Mosfet voltage