USB 2.0 data with HX3 and CCG3PA

[ChKi_4789686]

Hello,

I had another question regarding another post that I inquired about not long ago (link below):

https://community.cypress.com/t5/USB-Hosts-Hubs-Transceivers/HX3-Downstream-USB-3-0-to-Type-C-Recept...

For my application, I wanted to connect a USB Type-C receptacle to the CCG3PA for PD charging capability as well one of the downstream ports of the HX3 for USB 2.0/3.0 data. I originally wanted to retain legacy charging by connecting the Dp and Dm lines to both the CCG3PA as well as the HX3 since the CCG3PA has more charging profile capabilities. To reduce complexity, I decided to simply connect the Dp and Dm lines to the HX3 because BC1.2 and Apple Charging would suffice for the application. With this configuration, how would you recommend the downstream charging to be controlled considering that PD and legacy charging would be controlled by different devices? 

Could I do any of the following:

• Supply legacy charging through a USB charging switch and supply PD charging through the CCG3PA and tie the USB Type-C receptacle's VBUS to both?
• Connect the HX3's DS1_PWREN and DS1_OVRCURR to the CCG3PA gpios (with modified firmware) so that the CCG3PA can act as the charging switch for legacy charging?
• If neither of these would work, what is the best way to retain both USB2.0 data as well as legacy charging functionality with the configuration described above?

Thanks in advance!

Chris

[Sananya_14]

Hi Chris,

Could you please attach a basic system-level block diagram for the application?

The first method could work if the VBUS from the power switch or the FETs could be routed to the Type-C connector based on charging mode. For the second method, please note that the DS1_PWREN would be enabled even for the device enumeration i.e. when HX3 is not used for legacy charging and only data transfer. And we would also have to enable the appropriate legacy charging mode for CCG3PA to detect OCP.

Alternatively, please check HX3PD, our USB PD and Type-C capable hub which would allow PD or legacy charging along with USB 3.1 Gen 2 hub functionality. It may be an overkill for your application but would require less development effort as only the configuration would have to be changed.

Best Regards,

Sananya

[ChKi_4789686]

Hi Sananya,

I could probably explain the system to you as it's fairly simple. Essentially, the device is for an automotive application which would act as a USB Hub with the following requirements:

• Upstream:
  • USB 3.0/2.0 data (x1)
• Downstream:
  • Type-A receptacle with USB 3.0/2.0 data and legacy charging (x1)
  • Type-C receptacle with USB 3.0/2.0 data, PD, and legacy charging (x1)

Could you please expand a bit more on what you mean by

"The first method could work if the VBUS from the power switch or the FETs could be routed to the Type-C connector based on charging mode."

For my application, the Type-C receptacle would essentially look like the image below with DP1 and DM1 routed to the HX3 and VBUS from the power switch (controlled by the HX3) somehow tied to VBUS below. Would this be feasible?

I've taken a look at the HX3PD before and went a different route as I thought it was overkill as well. Also, from the datasheets it seemed like only the HX3 and CCG3PA were for automotive applications. Can the HX3C family be used for automotive applications?

Best Regards,

Chris

[Sananya_14]

Hi Chris,

Thanks for the details, sorry for the delay in response.

By the first point, I was suggesting a power OR-ing circuit where the VBUS would be controlled by CCG3PA when PD is enabled or by HX3 when BC1.2 is enabled. If PD charging is used, then CCG3PA would be responsible for fault detection and turn off the FETs. However, for BC1.2 charging, the PWREN from HX3 would be enabled even when there is only data transfer on HX3. So the power switch would remain enabled even when PD charging is used with CCG3PA. An easier option would be to allow CCG3PA to control both the charging modes and have HX3 without a power switch for data transfer since you have DP/DM always connected to it. This would also not cause any issues from CCG3PA stack perspective since it would be monitoring VBUS and might cause reset when there is no Type-C attach/BC1.2 attach and HX3 has enabled VBUS on the same connector.

No, HX3C is not available for automotive applications and isnt recommended to be used in new designs as well.

Best Regards,
Sananya

[ChKi_4789686]

Hi Sananya,

No worries, I really appreciate the feedback. 

I apologize for my repetitiveness.. I just want to make sure that I have a clear understanding of the functionality of the chipsets. In my previous post I recall you mentioning that connecting DP/DM to both the CCG3PA and the HX3 would only allow BC 1.2 CDP charging mode. This would still stand true if I were "to allow CCG3PA to control both the charging modes and have HX3 without a power switch for data transfer" - is that correct? 

And the only way to implement additional legacy charging profiles is to use a mux as you previously suggested? I was trying to avoid going this route to reduce complexity and components due to size constraints, but if these are my only options it seems like this would be the best choice for the application. 

Best Regards,
Chris

[Sananya_14 · Accepted solution]

Hi Chris,

Yes, that's correct because then CCG3PA would always have DP/DM connected to it so CDP only would allow both charging and data transfer on the lines. 

Adding a MUX and would allow additional legacy charging modes since we are basically switching between HX3 and CCG3PA based on whether charging is required or data transfer. As per my understanding, it would be simpler compared to the two methods you suggested since those require significant modification of the CCG3PA firmware for VBUS control based on the selected mode. 

Best Regards,
Sananya