TUSB320: USB C Charger Through Dongle with TUSB320

Hi Peter,

I'm having some trouble understanding the application. This dongle is meant to act as both a UFP and a DFP, depending on whether there is anything connected to the female type-C port of the dongle. If there is nothing connected, you want the male-port CC controller on the dongle to configure as a UFP, pulling power from the phone to power the dongle. When there is a connection at the female type-C port, you want the male-port CC controller to configure as a DFP, providing power to the smartphone. Is that correct?

In both cases, will data be sent to the dongle from the phone?

Please keep in mind that role of the CC controller does not change in real time. For the role of the CC controller to change, the CC negotiation process needs to take place again, either by disconnecting and reconnecting to the phone, or resetting the TUSB320. If you need to change the role in real time, a PD controller may be a better fit.

Additionally, I see there are two type-C ports on the dongle. We recommend a CC controller for each port, to ensure a proper connection over the CC pins.

Peter Grinalds said:

Our question is, should the VBUS_DET monitor the external power bus or the VSYS_5V bus?

VBUS_DET should be routed to the VBUS of the associated port, so SYS_5V from the male type-C ideally.

Peter Grinalds said:

Additionally, is it okay that LM66100 remains constantly "ON"? Or must its enable be controlled by the TUSB320 ID pin?

VBUS must be controlled via the ID pin, as VBUS being sent is part of the CC negotiation process. I would recommend routing the ID pin to the LM66100 and using that to control when VBUS is sent.

For the schematic: 

I see the OUT1/OUT2 pins are left floating. Is there any specific desired current between the phone and the dongle, I.E 5V/3A, or does the default 900mA work? If higher is needed, these pins should be used to communicate to whatever is pulling power from the phone through the male type-C port what the detected current advertisement is.

Again, I would recommend routing the ID pin to the LM66100, and routing VBUS_DET to the VBUS of the type-C male port.

I would also recommend using a second CC controller on the female type-C port, for current advertisement I would recommend the TUSB321.

Thanks,

Ryan

Hi Ryan,

Thank you so much for the assistance.

Yes, you are entirely correct with the intended work-flow. In both cased the USB+/- from the phone will go to the DAC/ADC.

Ah that is good to know about the CC controller negotiation trigger. In my mind I was thinking that renegotiation would occur when a cable is connected or disconnected from the female plug. But since the TUSB320 wouldn't be monitoring those lines (and since we'd never be sending power to that plug, only ever receiving power from it), that would not happen.

I think I will have to rethink the strategy here since the intended use-case is to basically build the dongle into a phone-case wherein the male USB port is never removed from the phone. I think I am overcomplicating it. I want the DAC to draw power from the phone when no external cable is connected. When an external cable is connected we want it to power both the phone and DAC. Is there a way to make this re-negotiation automatic?

Thank you so much for any input,

Peter

Hi Peter,

Peter Grinalds said:

Is there a way to make this re-negotiation automatic?

There is no way for it to automatically happen, you would either need to disconnect and reconnect the CC lines, or reset the TUSB320. The TUSB320 does have I2C support, you can reset the TUSB320 via I2C if that helps.

It sounds like you need some way to determine when a device is connected to the receptacle on your device, which can then route the incoming voltage from the receptacle to the DAC and phone, while initiating a reset and role change on the CC controller on the male type-C connector. This type of implementation may be easier with a PD controller, or with an I2C controller with the means of controlling the CC controller. I would recommend implementing a CC controller the female type-C port as well, as it can be used to help indicate when a connection has been made via the OUT1/2 pins.

Thanks,

Ryan

I'll look into that. Thanks Ryan. Maybe TUSB320 on the female port and PD controller on the male port.

Hi Peter,

Sounds good. Please let me know if any other questions come up.

Thanks,

Ryan