DN & DP of AP33772S not connected to Type-C connector

[OE4DEA]

Hi,
I noticed that you created labels for DN & DP of the AP33772S, but they are not connected to the Type-C connector.
Could you explain the reason for this design choice?
Thanks!

[CentyLab]

Hi @OE4DEA,

This design decision was an oversight from our team. We weren't sure if the DP+DN moisture detection feature would impact the data flow as this is one of the only two way to program the RP2040 IC. So the team has prioritize signal integrity and programmability for the RP2040.

[CentyLab]

@OE4DEA We have reported from other developers that connecting DN and DP from USB-C to both the AP33772S and micro-controller break USB2.0 connection. Cutting trace to the AP33772S resolve the issue.
We think that the AP33772S moisture sensing is mainly for power device application like chargers, drills..., and was not design for actual data line.

[OE4DEA]

Thank you for the clarification!
I had reached out to the manufacturer several times regarding this topic, but unfortunately never received a response.
I really appreciate your detailed follow-up!

[sslupsky]

I noticed the same thing in the schematics as well. For comparison, TI uses the SBU lines for moisture detection. I wonder if the SBU lines could be used with the AP33772S?

[CentyLab]

@sslupsky this idea is awesome. The AP33772S said that moisture detection is done by measuring impedance between the pins and GND. As we are in USB-PD mode, the SBU pins should not be operational. We will test it in our RotoPD circuit and circle back on this topic.