BQ25886EVM: How do I test USB CDP mode

Michael Jeong1

Expert 2630 points

Part Number: BQ25886EVM

Hi Linhong,

My thread was locked.

This issue was not cleared. so I want to re-open and ask some question.

(+) BQ25886EVM: Input Current Limit by D+, D- - Power management forum - Power management - TI E2E support forums

How should I test to see if this device works well in USB CDP mode?

For example, what kind of USB port on the laptop pc can I test it? Or I want you to test it and show me how it works.

Our customer is waiting your feedback for a long time.

Pls help us.

Best Regards,

Michael

over 2 years ago

0 Jeff F over 2 years ago

TI__Guru**** 167476 points

Hi Michael,

The USB BC1.2 spec can be downloaded at Battery Charging v1.2 Spec and Adopters Agreement | USB-IF. It gives the details for CDP ports.

For testing, you can monitor the D+/D- lines when VBUS is applied using an oscilloscope. You will see the correct pulses for CDP but the charger is waiting for a response from the USB port. If the response is not received, the charger drops down to SDP. Only a few older laptops have CDP ports (usually with a lightning bolt beside). Unfortunately, fewer still of those ports provide the response pulse in the time frame that the charger is expecting so the charge drops down to SDP.

Regards,

Jeff