TUSB2036: Developing USB solution (Tablet Host + charging, USBC PD input)

Hi,

Do you have a block diagram that you can share? 

With USB Type-C, the Power Role and Data Role are now two separate functions. For example, you can be a Data Source which being a Power Sink, or Data Source and Power Source. The roles can also be swapped as needed. Both the data role and power role are handled by the PD controller. 

With TUSB2036 hub, the hub downstream ports will always acts as a USB source, it can not act as a USB sink. Are you trying to connect the tablet to the upstream or the downstream of the hub?

Thanks

David

Hello. From what I understand about the protocol, I agree that a USB host can be a power sink. I am just having a hard time interpreting USB hub specifications to understand if they support that and are relevant to my system's use case.

With TUSB2036 hub, the hub downstream ports will always acts as a USB source, it can not act as a USB sink. Are you trying to connect the tablet to the upstream or the downstream of the hub?

Okay, good to know. If I'm understanding hub functionality correctly, the tablet should be upstream of the hub. Here is a block diagram showing the main use cases I need to handle (Charger plugged in, charger unplugged).  CONFIG A

As you can see in the simplified block diagram above, the controller would require two USB devices to connect to it.

This other configuration (CONFIG B) would also be acceptable:

In config A the controller would take in two usb devices. In config B it would only need to handle the tablet. In either case, the tablet needs to go into power sink mode (always trying to charge), data host mode. I wanted to see what controller options we have to make this work. The ideal would probably be config B since it would be a smaller hub. The key for us would be if the controller can automatically place the tablet into power sink, data host mode (i.e. minimal programming).

I apologize for any strange things/inconsistencies in the block diagram, as it is quite simplified. The power input for our system also has a battery backup, so disregard the config b, charger unplugged 0V input. Please let me know if anything needs clarification

Hi,

I am sending this question to our PD controller team for their input, I think for this particular case, you would need a PD controller such as TPS6598x controller.

Thanks

David

We sort of prefer to lean on a simpler option if possible. Ideally one simple one that manages the tablet. But im interested in hearing what options are available for either configuration.

Is there any new information for this?

What options for configuration B where we would like a simple programmable or preprogrammed/state machine USB Hub to negotiate simply to host mode + charge mode? Im looking for something resistor settable or that automatically negotiates the tablet to data host + accepts charge.

For configuration A that seems like the right solution, thanks. I want options for configuration B too..which would be a good amount simpler for us.

Hi,

Can you please take a look at TUSB8044A, https://www.ti.com/lit/ds/symlink/tusb8044a.pdf and in particular section 8.3.1 Battery Charging Features to see if the hub meets your design need?

Thanks

David

Before I go too crazy looking into this chip..is there a USB2 only "version" of this chip. The TUSB8044A is quite a behemoth for just using it in config B in the block diagram i sent.

Hi, 

Please take a look at TUSB4041I, https://www.ti.com/product/TUSB4041I.

Thanks

David

To clarify I'd like something that automatically places the tablet into a DFP (downstream facing port) and SINK. With no programming or at least resistor settable to configure it. 

Reading through the TUSB4041I it doesnt seem to allow USB charging support for the upstream port.

Hi,

We do not have a hub that can support USB charging for the upstream ports. 

Thanks

David

In that case, is a configuration like this possible?

Is there an IC that can autonomously place the tablet into SINK mode while the tablet continues as data host role?

Hi,

When you say SINK mode, I assume you want to be in POWER.SINK mode?

Thanks

David

Yes, in POWER.SINK. So that the tablet may charge.

Hi,

I think you would need a PD inside the tablet as well. The PD will configure the tablet as DATA.SOURCE and POWER.SNK. The IC will be another PD that will configure itself as POWER.SOURCE.

I moved the ticket back to the PD team for their comment.

Thanks

David

The tablet is an Apple product..it is not custom. It definitely has a USB controller chip.

Hi Pablo,

I help support the USB PD group. It looks like you're designing a USB device that requires a PD controller to act as the power source to an upstream tablet.

Is my understanding correct?

Thanks,

Matt Schafer

I need the tablet to act as a USB 2.0  downstream facing port (HOST) while still charging (SINK). And we want it to be autonomous. We dont need fancy features. We would like a solution where we can configure with resistors, for example. We dont want to have to configure the ports through I2C.

The tablet must control a single UFP device.

Is the part number really TPS55288? It seems to be a buck-boost converter. There is mention of PD but not of power roles.