About USB_H1_VBUS and USB_OTG_VBUS in i.MX6DQ.

[keitanagashima]

Dear All,

My customer will use USB OTG and Host1 in i.MX6DQ.

[Q1]

Refer to "PMU_REG_3P0 field descriptions" in IMX6DQRM(Rev.3).

"VBUS_SEL” bit can select input voltage source for LDO_3P0 from either USB_H1_VBUS or USB_OTG_VBUS.

Is it both need input power of  USB_H1_VBUS and USB_OTG_VBUS?

(i.e. If either is inputted, is power supplied to both of Host1 Phy and OTG Phy?)

[Q2]

If good in either input USB_H1_VBUS or USB_OTG_VBUS, Why does two VBUS ports exist?

Best Regards,

Keita

[CarlosCasillas · Accepted solution]

Hi Keita,

The register allows the selection of VBUS signal to be inputted to the LDO_3P0 regulator, so, as you mentioned, depending of the scenario it may not be useful, but adds flexibility to USB IP depending for example if just one USB controller will be used.

Hope this will be useful for you.
Best regards!
/Carlos
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[CarlosCasillas]

Hi Keita,

1. Yes, either USB VBUS could be used as input of the LDO_3P0, as both USBs (H1 and OTG) are used as Host.
2. The two VBUS could be used to detect VBUS signal depending of the application scenario, like detecting if VBUS is applied to the OTG port when used as Device.

Hope this will be useful for you.
Best regards!
/Carlos
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Note: If this post answers your question, please click the Correct Answer button. Thank you!
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[keitanagashima]

Dear Carlos,

Hello. Thank you for your reply.

> 1.

OK. Thank you very much!

> 2. The two VBUS could be used to detect VBUS signal depending of the application scenario,

> like detecting if VBUS is applied to the OTG port when used as Device.

Sorry, I couldn't understand well..

In case of using USB OTG (as device function) and USB Host1 (as host function):

I think that "VBUS_SEL” bit was selected USB_H1_VBUS as input voltage source for LDO_3P0.

So, USB_OTG_VBUS seems not need.

Could you  tell me the more detail?

Best Regards,

Keita

[CarlosCasillas]

Hi Keita,

5V power should be supplied to the VBUS pin(s) to source the LDO3P0 supply in order for USB to work properly. USB_OTG_VBUS typically is a 5V interruptible supply, such as sourced from a USB power chip. If the host port is used, USB_H1_VBUS must be on an uninterruptable 5V supply.

Each VBUS is 25 mA max. H1 should not leach 25 mA from the USB power chip. USB_H1_VBUS should be tied to 5V; it doesn't need the USB power chip. Treat USB_H1_VBUS as a normal LDO supply connection. According with its functionality, it would be called “VDD_H1_IN” instead of “USB_H1_VBUS”.

You could also refer to section 3.5.2. “PMU_REG_3P0” of the “i.MX 6 Series USB Certification Guide” document available here.

Hope this will be useful for you.
Best regards!
/Carlos
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Note: If this post answers your question, please click the Correct Answer button. Thank you!
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[keitanagashima]

Dear Carlos,

Hello. Thank you for your reply.

Sorry, I couldn't understand well.

Let me confirm again.

My customer's system will use USB OTG and Host1 at the same time in i.MX6DQ.

First, refer to "PMU_REG_3P0 field descriptions" in IMX6DQRM(Rev.3).

"VBUS_SEL” bit can select input voltage source for LDO_3P0 from either USB_H1_VBUS or USB_OTG_VBUS.

Next, refer to "3.5.2.  PMU_REG_3P0" in IMXUSBCGUG(Rev.0).

"This register defines the control and status bits for the internal LDO_USB module, which is powered by

either of the two USB VBUS pins."

[Q1]

So, I think that either one (USB_H1_VBUS or USB_OTG_VBUS) should input to LDO_3P0.

Is it both need input power of  USB_H1_VBUS and USB_OTG_VBUS on this system?

[Q2]

Why does two VBUS ports exist?

Best Regards,

Keita

[keitanagashima]

Dear All,

Hello. Do you have any update?

Best Regards,

Keita