Inquiry Regarding STMicroelectronics' EVLVIPGAN100PD Reference Design

[nesrine12]

I hope this email finds you well. My name is Nesrine AYED, and I am a student and i'm currently working on my final year project, which involves the development of a 100W USB Power Delivery (PD) adapter. In my research, I came across the EVLVIPGAN100PD reference design from STMicroelectronics, and I am interested in obtaining further information to aid in my project development.

I would like to inquire about the following aspects of the reference design:

Output Voltage Flexibility:
Could you please clarify whether the EVLVIPGAN100PD evaluation board is capable of delivering different output voltages based on the device connected, or does it provide a fixed voltage output?

Communication Protocol:
I am curious to know how the VIPERGAN100 and the USB PD controller STUSB4761 communicate with each other within the reference design. Specifically, I am interested in understanding if there is a communication protocol utilized (e.g., I2C, SPI) for this purpose.

Connector Functions:
Upon reviewing the daughter board schematic, I noticed the presence of two connectors labeled TRIM and PG. I would appreciate it if you could provide insights into the functions and utility of these connectors within the reference design.

Gaining clarity on these aspects would greatly contribute to my understanding of the reference design and its suitability for my project goals.

Thank you very much for your attention to this matter. I look forward to receiving your response and further guidance.

Best regards,

[Peter BENSCH]

• Output voltage flexibility:
  The output voltage is defined via 5 PDOs, the default settings are 5V 3A, 9V 3A, 12V 3A, 15V 3A and 20V 5A. The PDOs can be changed in the STUSB4761 and its I2C interface.
• Communication Protocol:
  There is no communication and no protocol. The USB PD controller STUSB4761 functions together with the VIPERGAN as a voltage regulator. It measures the VBUS output voltage via its pin 12 (Vsense) and controls the VIPERGAN100 via its Opto output and the FB_OUT network.
• Connector Functions:
  PG is included in the schematic, but not in the layout. TRIM is directly parallel to PG in the schematic and fulfils exactly the same task of programming (PG) or setting (TRIM) the STUSB4761 via I2C.

For details on programming the PDO, you should read the documents for the STUSB4761.

Hope that helps?

Good luck!
/Peter

[nesrine12]

Hello, 

Thank you very much for your reply. I have another question. I want to verify wether the output voltage is delivered according to the device that will be connected such as laptop, phone... that means that the output is given based on the requirement of the device?

[Peter BENSCH]

For this reason, there is the STUSB4761, which informs the connected sink (e.g. notebook, phone) via CC channel (CC1, CC2) which PDOs are available. Of these PDOs, the sink then requests the one with the highest possible voltage and current.

[nesrine12]

That's clear now. Thank you very much!

[Peter BENSCH]

The voltage VSRC is the output voltage of the quasi-resonant flyback converter, which supplies both U3 (STUSB4761) via its pin VDD and is switched to VBUS via Q3 and Q4 and thus to the USB-C socket.

If you look at the parameters of the STUSB4761 in its data sheet, you will find the voltage range 4.1V to 22V for VDD in Section 6.2, Table 15, which is covered by all PDOs.

Hope that answers your question?

Good luck!
/Peter

[nesrine12]

Hello Mr Peter, I have another question please: did the vipergan100 will be powered by the aux 1 and aux 2 of the flyback transformer and the PFC Controller L6564 is powered by the output of the vipergan100 "VDD_Viper" ?

if this is correct, what current and voltage need both the vipergan100 and the L6564 to be powered on?

[Peter BENSCH]

Essentially correct, the VIPERGAN100 is supplied by AUX1 and AUX2 after a half-wave rectification via the depletion FETs Q2 and Q3, which operate as simple voltage regulators. The output voltage of these voltage regulators Q2/Q3 has the network designation VDD_Viper. However, the L6564 is only supplied from VDD_Viper at the start and then from the secondary winding of the PFC choke L2 via D7 (self supply).

The output voltage VDD_Viper is about 15V (VDz2+Vgs), where VDz2=18V and Vgs~(-2.5 ... -3V). The currents required by L6564 and VIPERGAN100 can be found in detail in their data sheets, in total we are talking about approx. 15...20mA.

[nesrine12]

Hello Mr Peter, hope you are doing well. I want to ask about the stusb4761 if it will be powered by the vsrc directly. if the vsrc is 20V @5A then stusb4761 will not support this current because it is powered by a current in mA. also i want to know wich current is flowing in 1V2 and 2V7. Your help will be appreciated.