I'm trying to implement a USB PD controller, STUSB4500, but the typical application example shows 2x P-Channel MOSFETs STL6P3LLH6 with different arrow indications. I'm now confused about the pins, T4 has the same MOSFET drawing as in the STL6P3LLH6 datasheet, so the left pin is the drain (5,6,7,8) and the right source (1,2,3). But for T1, which is reversed, is the right side pins 5,6,7,8 or 1,2,3? Any further clarifications on this will be appreciated.

Image Sources/Datasheet links:

STUSB4500: https://www.st.com/en/interfaces-and-transceivers/stusb4500.html

STL6P3LLH6: https://www.st.com/en/power-transistors/stl6p3llh6.html



  • \$\begingroup\$ Google "back to back MOSFETs". \$\endgroup\$ Commented Jan 26 at 12:56
  • \$\begingroup\$ Emerson - Hi, (a) To comply with the site rule on referencing, please edit your question & add the PDF / video / webpage name & link to the source of each copied / adapted image. (b) Did you mean the STUSB4500? Doing a quick search, I couldn't find a USB PD controller with the TUSB4500 part number. TY \$\endgroup\$
    – SamGibson
    Commented Jan 26 at 14:06
  • \$\begingroup\$ thank you @SamGibson, this has been fixed. \$\endgroup\$
    – Emerson
    Commented Jan 26 at 14:59

1 Answer 1


The two sources (1,2,3) are connected together. The grey thick line has obscured the internal connection from body to source.

This is a standard back-to-back MOSFET connection to make a bilateral switch.

enter image description here


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