Dual STUSB4710 Power Management

[YunusBasegmez]

I am designing a usb type-c charger. 

I want to use 2 microcontroller and 2 STUSB4710.

Type-C Output will be 20V 3.35A 67W.

I want to do power management between these USB Type-C outputs.

I have questions. Can you please answer them?

 

1. Are there any I2C command to close the output pmosfets with STUSB4710?

2. Can microcontroller reduce the output current capabilities of STUSB4710 while a device connected to USB Type-C sinking some current. For example,

• Default output contract is 20V 2.25A
• Send I2C command to STUSB4710 and change the output capabilities to 20V 3A.
• Output contract is now 20V 3A.
• Attach a usb device which sinking 20V 3A power and start consume 60W.
• Send I2C command to STUSB4710 and change the output capabilities to 9V 2.25A.
• STUSB4710 send message over CC communications.
• Sink device reduce power consumption to 9V 2.25A.
• Is the scenario possible? If there is a problem, can you correct it?

3. Is there any other way to reduce sinking current of the connected usb device?

4. STUSB4710 supports 20V 5A. But Vconn is not supported with STUSB4710. Is there a standard incompatibility?

5. Is 20V 3.35A type-C output possible with STUSB4710?

6. I have found this post https://community.st.com/t5/interface-and-connectivity-ics/stusb4700-4710-i2c-register-details/td-p/234334. But I did not find any clear guidelines(step by step) for changing register and effects of it. Also some registers contained TBD values.

[NBALL]

Hello
AS per USB power delivery, source cannot provide only 20V/3A.

All power sources need to follow so called 'power rules': 67W charger needs to at least propose: 5V/3A - 9V/3A - 15V/3A and 20V/3.35A
Current can be higher than 3A for PDO< 20V but it needs to be always <=67W if the charger is labelled 67W

To provide current >3A, source shall ensure that the cable can sustain more than 3A. All USB cable are guarantee to sustain 3A but not all of them can sustain 5A. In order to read cable characteristics, source shall supply Vconn and shall send messages dedicated to cable (SOP' messages).
STUSB4710 cannot do this functionality. To propose more than 3A with stusb4710, the source needs to be so called 'captive cable': i. e cable is undetachable. connector is a plug instead of being a receptacle.

I port is labelled 67W max, overall power can be reduced due to sharing but voltage nodes should be kept, as per USBPD spec. i.e if power is reduced to 40W, it should offer 5V/3A - 9V/3A - 15V/2.66A - 20V/2A

Hope it helps

Best regards

Nathalie

[YunusBasegmez]

Thanks you for information. But I did not see answers of questions below. Can you please reconsider it?

1. Are there any I2C command to close the output pmosfets with STUSB4710(or STUSB4761)?

2. Can microcontroller reduce the output current capabilities of STUSB4710(or STUSB4761) while a usb sink device connected to USB Type-C sinking some current. For example,

• Default output contract is 20V 2.25A
• Send I2C command to STUSB4710(or STUSB4761) and change the output capabilities to 20V 3A.
• Output contract is now 20V 3A.
• Attach a usb device which sinking 20V 3A power and start consume 60W.
• Send I2C command to STUSB4710(or STUSB4761) and change the output capabilities to 9V 2.25A.
• STUSB4710(or STUSB4761) send message over CC communications.
• Sink device reduce power consumption to 9V 2.25A.
• Is the scenario possible? If there is a problem, can you correct it?

3. Can microcontroller reduce the output current capabilities of STUSB4710(or STUSB4761) while a usb sink device not connected to USB Type-C. For example,

• Default output capabilities of STUSB4710(or STUSB4761) is 20V 2.25A.
• Send I2C command to STUSB4710(or STUSB4761) and change the output capabilities to 20V 3A.
• Output capabilities is now 20V 3A.
• Send I2C command to STUSB4710(or STUSB4761) and change the output capabilities to 9V 2.25A.
• Is the scenario possible? If there is a problem, can you correct it?

4. Is there any other way to reduce sinking current of the connected usb device?

[NBALL]

Dear  YunusBasegmez,

Question1:

There is no possibility to close power mosfet thru I2C command: it is only managed by hardware.

Question 2:

If you need to send some updated source_cap, you need to:

1/ update the PDO fields into PDO registers
2/ write @x1A = x02 : this command will send source_cap message with PDO stored into registers

Please note that stusb4710 does not limit the current. It sends instruction to sink about the max current available. Sink is responsible to not sink more than the request done.

question 3:
Updating the current in source_cap to force sink to reduce its power is the only way to reduce the sinking current

question4: 

STUSB4710 can support 100W only in case of captive cable application. In this case, there is no need to send message to cable to know if it can support more than 3A

Question 5:

More than 3A is not allowed by the standard if source does not check that cable can sustain more than 3A

I hope that it will help :)

Best regards

Nathalie

  

[YunusBasegmez]

Thanks you for a quick respond.

What can you say about STUSB4761?

Can STUSB4761 handle this scenarios?

Can you answer the same questions for STUSB4761?

[MKN]

Situation on STUSB4716 is unpleasant.

No register description available and without a doubt different to 4700A.
You have to use STSW-STUSB005 tool to create and export a NVM configuration but you never know which bit does what.

First PDO Profile is always 5V and without cable ID chip STUSB4761 will not deliver more than 3A.
You can outsmart it with a wrong current shunt but I dont know if a 5A negotiation ist possible without a 5A cable ID chip.

You can't control mosfets directly over I²C but you can manipulate the temperature measuremen.

Look at page 7 in Datasheet.

 

[NBALL]

Hello
As mentioned in our datasheet, I2C is to configure stusb4761 internal non-volatile memory (NVM).

NVM is not a I2C register map, it cannot be written infinite number of time. That's why we do expect to have STUSB4761 NVM configuration setting done once and not to try to change NVM on the fly.

Best regards

Nathalie

[MKN]

Hi,
we are using the STSW-STUSB006 I2C Lib whose only pupose is the programming of the STUSB4761 with an own MCU. What else does ST think what the Customers will do with it?

The datasheet explicit describes multiple reprogramming and what to do that the new configuration will take effect. Definitely not 'write once'
I assume the NVM is a normal flash with 10.000 to 100.000 write cycles.
Please clarify the maximum allowed write cycles.

It would be better if ST clearly says what this Chip can do and what not.
Not this information obscurity of unspoked things to 'protect' the customer from his own decisions he made with much to less informations.

 

Best Regards

Michael