TUSB4041I: CDP and design consideration

Kailun Liu said:

. Is this difference influenced by the VBUS detection status of the upstream port? If not, what influences it?

If  USB_VBUS pin *is still high ( powered by fixed supply, upstream port is still considered connected even if the USB cable is disconnected. 

Kailun Liu said:

In automode mode, Port 1 does not support CDP. Which mode does it support?

DCP mode and Divider Mode.

Kailun Liu said:

If we want to use the automode function, does the upstream port not need to be connected? (In our actual application, the upstream port is connected long-term)

in Automode, upstream port has to be disconnected.

Kailun Liu said:

If the hub is to be used as a self-powered standalone USB hub product, how should the VBUS of the upstream port be connected?

it's best to connect USB_VBUs pin to the vbus of the upstream port connected though voltage divider

Kailun Liu said:

What does the Bat Charging support function of the downstream port mean?

it mean only downstream port support BC1.2, or divider mode , upstream port does not support

Kailun Liu said:

If J2 is to use the TYPE-C port and DN1_VBUS is to remain normally off (powering on only when a device is detected), how should pin4 PWRCL1/BANTEN1 behave?

for Type-C port, VBus or charging  is controlled by PD /CC controller, or charign device, PWRCL1/BANTEN1  should not be used.

Kailun Liu said:

If we want to use an MCU to control the power on/off state of DN1_VBUS, how should PIN4 and PIN14 behave?

If you  use MCU to control DN1_Vbus,  make sure FAULT pin of power switch is connected to MCUGPIO  and hub OVERCUR  pin, so both MCU and Hub know overcurrent issue  happened or cleared,  PWRCL1 pin can be ignored.

Best

Brian

Hi Brian, 

Appreciated for your detail response. 

The downstream ports of the HUB need to be configured in Automode, which requires that the Upstream must be disconnected, meaning the VBUS voltage is less than 4V.

Since in our actual product application, the Upstream port remains connected for a long time, it is necessary for pin 16 of the HUB to be kept low at all times in order to ensure the Upstream port is in a disconnected state.

In the actual product, the VBUS supplied to the downstream port comes from other power management chip, meaning the hub operates as a self-powered standalone USB hub product. The reply also suggests that in this case, pin 16 should normally monitor the Upstream VBUS voltage. There seems to be a contradiction regarding the configuration of pin 16. Please help confirm.

Additionally, if pin 16 is kept low at all times, will it affect DM/DP data communication on the Upstream port?

If pin 16 is low, hub think the upstream port is disconnected.

So if you can control pin 16 on and off, then it should work.

Best

Brian

Thanks Brian!!

1. When pin 16 is at a low level, the HUB considers the upstream to be disconnected. At this time, does the data communication function of the upstream port's DM/DP work properly?

2. If the data communication function of the upstream port is affected at this time, does it mean that pin 16 needs to be connected to the motherboard's constant DC 5V and cannot be connected to VBUS, because VBUS experiences power interruption during charging and discharging?

3. If pin 16 is connected to a constant power supply, then the downstream port can only operate in CDP mode.

4. Apart from differences in current capability, are there any other differences between CDP and DCP?