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USB EZ-PD Type-C

New Contributor

We are looking to design a dual USB-C single USB-A charging port. Using a non-isolated buck converter to provide VBUS power. The spec. sheets figure 8 is what we've settled on as a reference we want to use. Clarifications I need from you are.

  1. Figure 8 doesn't show the USB-A port. Would it be correct to connect it to

5 – DP1/P1.2 USB D+/Port 1 pin 2: GPIO/UART_1_TX1/AFC/QC/BC 1.2/Apple Charging/No IEC

6 – DM1/P1.3 USB D-/Port 1 pin 3: GPIO/UART_1_RX1/AFC/QC/BC 1.2/Apple Charging/No IEC

  1. As see in figure 8 for the USB-C connector current monitoring is done using a sensor resistor connector to pin 19. We would want to monitor current through the USB-A.         Would the correct approach be to connect an equvialent analog voltage to one of the GPIOs we will have available ( 5,6) configured in sofware as an analog inputs.
  2. What are the max and min voltage levels of of the FB pin from the CYPD3175? Figure 8 shows it connected directly to the resistor divider connected to the converter. on past designs i have usally had to  use a buffer type device (diode, opamp) separating the CYPD3175 FB pin from converter FB pin. Is figure 8 correct in that i should connect converter FB pin to the CYPD3175 FB pin?
  3. What are the steps required to have Cypress to review out schematic design?
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Moderator
Moderator

Hello,

1. You can use Fig 8 as a reference. Please see Fig 9 for how to implement a Type-A port connection. You can use DP1/DM1 - P1.2/P1.3

2. You are right, you can use the same mechanism of shunt resistor on the VBUS path for Type-A and the shunt voltage can be measured on a GPIO.

3. Yes, Fig 8 is correct. It is a direct connection. The minimum FB pin voltage at which the FB loop functions properly for a wide temperature range is about 1 volt. Less than that, you might see some error when temperature variation is introduced. There is no max limit as such.

4. Please select a suitable reference design and follow the schematics - this is the recommedend way. I would suggest using this reference design as a starting point and then add the other CCG3PA for the 2nd USB-C port. Once you have an initial design you can create another thread for the schematic review.

Regards,

Rajath

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1 Reply
Moderator
Moderator

Hello,

1. You can use Fig 8 as a reference. Please see Fig 9 for how to implement a Type-A port connection. You can use DP1/DM1 - P1.2/P1.3

2. You are right, you can use the same mechanism of shunt resistor on the VBUS path for Type-A and the shunt voltage can be measured on a GPIO.

3. Yes, Fig 8 is correct. It is a direct connection. The minimum FB pin voltage at which the FB loop functions properly for a wide temperature range is about 1 volt. Less than that, you might see some error when temperature variation is introduced. There is no max limit as such.

4. Please select a suitable reference design and follow the schematics - this is the recommedend way. I would suggest using this reference design as a starting point and then add the other CCG3PA for the 2nd USB-C port. Once you have an initial design you can create another thread for the schematic review.

Regards,

Rajath

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