TUSB8043: Upstream and Downstream Power Supply

Yuta Nishie

Part Number: TUSB8043

Hi,

I have any question about upstream and downstream power supply(VBUS).

・upstream

1. Because there is no need to monitor the power supply of VBUS, is it OK to connect USB_VBUS of 48pin to GND at 10 kΩ?
Even if there is no need to monitor the voltage, do I have to connect it as shown in Figure 28. Upstream Port Implementation on the datasheet?

The host (SoC) and TUSB8043 are always connected on one board.
There is no hot-swap.

・downstream

2. When does the device (keyboard, etc.) start to be powered?
Is it correct to assume that the device starts to be powered when connected to one of the Downstream Port 1~4 of the TUSB 8043?

3. I would like to know how the TUSB8043 controls the external VBUS when the device is connected to the TUSB8043.
The customer wants to control power sharing to the device all at once.
The customer's configuration is below, what would it look like in this case?

PWRCTLx：L

SMBUSz：H

FULLPWRMGMTz：L

PWRCTL_POL：H

GANGED：H

AUTOENz：H

Best Regards,

Nishie

over 1 year ago

+1 Brian Zhou over 1 year ago

TI__Guru** 117725 points

1: USB_VBUS is used to detect if vbus from host is there. if alwasy connected, you need to bias USB_VBUS with 0.5v.

2: you should always supply Vbus for downstream port devices.

3: PWRCTLxis used to control Vbus switch for downstream port vbus. if overcurrent happens ( goes low), PWRCTLx will turn off Vbus switch.

suggest GANGED：L

Best

Brian

0 Yuta Nishie over 1 year ago in reply to Brian Zhou

Genius 3320 points

Hi Brian-san,

Thank you for your support. I understand No. 1 and No. 2.

Brian Zhou said:
3: PWRCTLxis used to control Vbus switch for downstream port vbus. if overcurrent happens ( goes low), PWRCTLx will turn off Vbus switch.

->4. Is PWRCTLx=Low only when Overcurrent happens?

5. When is PWRCTLx=High output? Could you please provide a timing chart after applying the power supply voltage?

Brian Zhou said:
suggest GANGED：L

->6. A customer wants to use one load switch to control two VBUSs. Should GANGED=L even then? I assume that GANGED=L is the case when there is one load switch connected to each downstream port.

Best Regards,

Nishie

0 Brian Zhou over 1 year ago in reply to Yuta Nishie

TI__Guru** 117725 points

if just one switch, then GANGED=H.

Regards

Brian

0 Yuta Nishie over 1 year ago in reply to Brian Zhou

Genius 3320 points

Hi Brian-san,

Does "just one switch" mean one switch for multiple downstream ports? Or does it mean one switch for one downstream port?

Also, please answer PWRCTLx of No.4 and No.5.

Best Regards,

Nishie

0 Brian Zhou over 1 year ago in reply to Yuta Nishie

TI__Guru** 117725 points

for 4: PWRCTLx depends PWRCTL_POL, since PWRCTL_POL is H for your design, PWRCTLx will be low when overcurrent happens

5: I will draw one soon.

6: GANGED should be H if you have one switch to control two ports.

Best

Brian

0 Yuta Nishie over 1 year ago in reply to Brian Zhou

Genius 3320 points

Hi Brian-san,

Thank you for your support.

I am looking forward to your answer No. 5.

Thank you in advance for your cooperation.

Best Regards,

Nishie

+1 Brian Zhou over 1 year ago in reply to Yuta Nishie

TI__Guru** 117725 points

for #5:

0 Yuta Nishie over 1 year ago in reply to Brian Zhou

Genius 3320 points

Hi Brian,

Thank you for your support!

Best Regards,

Nishie

Interface

Interface forum

TUSB8043: Upstream and Downstream Power Supply