USB & DisplayPort to USB-C Alternate Mode (with PD) adapter


What is USB-C:

A USB-C connector can transmit both USB and DisplayPort signals if it supports DisplayPort Alternate Mode.

Reasons to use a USB-C with DisplayPort Alternate Mode device:

  1. You have a display such as the ASUS MB169C+ that only has a USB-C input.

  2. You have a USB-C display adapter that you would prefer to use over a DisplayPort display adapter.

  3. You have a USB-C hub that also has a DisplayPort output.

Problems to solve:

  1. You have a computer (old or new) with no USB-C Alternate Mode ports, or not enough Alternate Mode ports.

  2. You have a new computer with a USB-C Alternate Mode port (or Thunderbolt 3 port) but it is connected to the integrated graphics of the CPU and you would prefer to use the capabilities of a graphics card.


An adapter with one output: USB-C female connector supporting USB 3.1 gen 2 (10 Gb/sec), DisplayPort 1.3 Alternate Mode, and Power Delivery 2.0. The connector has to be female to support hubs and display adapters that use a male connector that cannot be detached.

The adapter would have 3 inputs:

  1. USB input (3.1 gen 2; 10 Gb/s) from 10 inch USB-A male. The following would also work: USB-B female, or USB-C female with separate cable. USB-C male connector would not be acceptable as it cannot be connected to a USB-A female port.

  2. DisplayPort 1.3 input (HBR3) from a 10 inch Mini DisplayPort connector. This is more compact for laptops. Desktops can add a DisplayPort to Mini DisplayPort adapter. A DisplayPort male connector would also work. It could use a female DisplayPort or Mini DisplayPort or USB-C connector with separate cable.

  3. An optional power supply input for power delivery up to 100W (or the more usual 60W) in case a device requires more than the power supplied by USB-A or DisplayPort. If possible, make the USB and DisplayPort connections optional as well.


The TUSB1046-DCI with TPS65983B and TPD8S300 seem most relevant.


The SUNIX (UPD2018) USB 3.1 Dual Port USB-C PCI Express (w/Alternate-Mode) does basically the same thing except it gets USB from an included controller chip (ASM1142) connected to a PCIe 3.0 x1 slot instead of an existing USB port.

The Cypress CY4501 CCG1 Development Kit includes a CCG1 Host Board which does what we want plus a lot of extra stuff we don’t need. I don’t know if that supports SuperSpeed+ 10 Gb/sec though.


Hi joevt,

Very interesting idea conceptually! (Hadn’t seen that Sunix card – might pick one up to tinker with.)

Given the compatibility challenges with both USB-C and DP, this would be a difficult product to develop, market, and support.


The compatibility challenges with both USB-C and DP hasn’t stopped you from making other USB-C and DP adapters.

Anyway, I’ve tried the Sunix UPD2018 card in one of my GA-Z170X-Gaming 7 motherboard’s PCIe 3.0 x1 slots. Sadly, my GA-Z170N-Gaming 5 motherboard doesn’t have a spare PCIe slot, which is one of the reasons for my suggestion of an external adapter.

The UPD2018 seems to work as advertised. I was able to use various USB devices (1.1, 2.0, 3.0, 3.1) and USB-C display adapters (2 lanes=4K30Hz, 4 lanes=4K60Hz). I don’t have any combination USB 3.1+DisplayPort (2 lanes) devices to test.

I was able to use the Plugable USBC-VGA adapter (usbc-vga) to output from one of my Nvidia graphics card’s DisplayPort ports. The usbc-vga supports 2048x1536@73Hz (330 MHz) but for some unknown reason only 1920×1200@60Hz is advertised?

The UDP2018 uses the following chips (in addition to the ASM1142 USB 3.1 Host Controller chip mentioned in the product description):

  1. TUSB1046-DCI USB Type-CTM DisplayPortTM ALT Mode 10 Gbps Linear Redriver Crosspoint Switch
  2. CYPD4225-40LQXI EZ-PDTM CCG4 dual port DRP controller
  3. TPS54427 4.5-V to 18-V Input, 4-A Output Single Synchronous Step-Down Switcher With Integrated FET
  4. HD3SS3212x Two-Channel Differential 2:1/1:2 USB3.1 Mux/Demux

It also has a 4 port USB 2.0 hub connected to one of the ASM1142’s USB 2.0 ports. One of the hub’s outputs is for one of the USB-C outputs. Another hub output is for an interface used for firmware updates. This is probably not for the ASM1142 chip which would have firmware updated from PCIe.
5) CY7C65634 HX2VLTM Very Low Power USB 2.0 Hub Controller
6) CY7C65211 USB-Serial Single-Channel (UART/I2C/SPI) Bridge with CapSense® and BCD
7) HT24LC02 CMOS 2K 2-Wire Serial EEPROM
8) MX25L2006E 2M-BIT [x 1/x 2] CMOS SERIAL FLASH
9) etc.


This may be overly complicated for the use case. Myself, I would buy and use a USB-C to DisplayPort adapter (or cable) with power delivery passthrough to the host device.

Essentially, a but with a DisplayPort alternate mode out instead of USB ports.


The use case is for a computer that doesn’t have USB-C alt mode, to add USB-C alt mode.

Your suggestions require a computer with USB-C alt mode, or my suggested adapter.

Google with “usb-c power delivery displayport” (no quotes) will find USB-C with alt mode to DisplayPort adapters with power delivery input. Some include a USB 3.0 type A port which might half the DisplayPort 4K output from 60 Hz to 30 Hz. If the adapter was smart it would allow 60 Hz when only a USB 2.0 device is connected, or it would force USB 2.0 when 4K 60 Hz is selected.

The usbc-hub3p requires USB only, and does not provide USB-C alt mode. I agree it would be more useful if it included a USB-C alt mode output in case the USB-C port that it is connected to supports USB-C alt mode. The ud-ultcdl and ud-ca1 would be alternatives to the usbc-hub3p with alt mode output, except the alt mode output is a HDMI port instead of a USB-C port, limiting the possible functionality (unless you want HDMI, then it’s one less adapter to buy).


Aha, I see where I misread the request! I have USB3 and DisplayPort out, and I want USB-C out for e.g. MB169C+.

I would expect a big customer base for this request would be Surface Pro owners.


I found a youtube video using the Sunix UPD2018 as an external DisplayPort input to USB-C output adapter.
“Demonstration of Sunix UPD2018 functioning standalone as DisplayPort to USB-C adapter”…

So that could be used with computers that don’t have a free PCIe slot. However, this method means there’s no USB communication.

The new Plugable usbc-ps-60w has power input, and USB-C output. If it had USB and DisplayPort input and a USB-C female port then it would be a perfect solution.


Hi All,
I have been looking for a solution to this same problem in order to use my LG Ultrafine 4k Monitor with a standard DisplayPort output device. I have had to settle on the method from the video above using the Sunix UPD2018.

However, I bought and tried this… in the hope it might work. It is very close to what @joevt is thinking.

Sadly it didn’t work, I think it lacks the right electronics or was designed only to work with the Wacom tablet but there is a need for something like this.


The Delock 89582 appears to be an identical product to the Sunix UPD2018. The IT-GO “ADP-099-31” appears to be the most inexpensive PCIe enclosure.

If your computer doesn’t have a spare PCIe slot, the cards can work as a DisplayPort to USB-C converter using an externally powered PCIe slot. They have a cable to connect to PCIe, mPCIe, M.2, U.2, or ExpressCard which will allow mixed USB + DisplayPort (unless the firmware blocks it, in the case of some M.2 or mPCIe slots?). If you don’t connect the cable then the card can’t be used in mixed USB + DisplayPort mode but that shouldn’t be a problem if you only need DisplayPort.

Another alternative is a Thunderbolt 3 add in card like the GC-ALPINE RIDGE. This will do DisplayPort to USB-C alt mode conversion and DisplayPort (single or dual stream) to Thunderbolt 3 conversion even in a computert that doesn’t support Thunderbolt add-in cards. The card provides two USB-C ports instead of just one. The card also can work externally, however, the DisplayPort conversion process doesn’t start unless you connect the external PCIe slot adapter’s cable to a PCIe slot of a computer at least momentarily. It doesn’t need to be the same computer as the source of the DisplayPort. The conversion process continues even after the PCIe cable is disconnected, until the card stops receiving power. I will test a multi-slot PCIe adapter to see if the addition of a PCIe bridge chip on the adapter will start the display port conversion process without connecting the adapter to a computer. There is also the 5 pins of the header on the add-in card to consider. It seems the card works when the pins are left floating (unconnected), but there could be issues.

While DisplayPort conversion always works (when started as described above), PCIe over Thunderbolt and the USB 3.1 gen 2 controller will not work on the add-in card unless it is connected to a PCIe slot that the firmware of the computer allows for Thunderbolt. For example, a Gigabyte Z170X Gaming 7 motherboard will enable PCIe transmission and the USB controller of an add-in card when it is connected to the PCIEX4 slot, but not any other slot. This is true even though the Gigabyte Z170X Gaming 7 does not have a Thunderbolt add-in card header. Even so, there may be issues where the USB controller does not get enabled (the PCIe device for the controller is not enumerated by the OS). This may be because of the floating pins of the header connector? In other PCIe slots, the root port gets a PCIe bus assigned, but the first Thunderbolt PCIe bridge is not enumerated. Under the first bridge are supposed to be 4 other bridges:
0: Thunderbolt NHI
1: Thunderbolt port 1 bridge for PCIe communication -> multiple buses
2: Thunderbolt USB 3.1 gen 2 controller
4: Thunderbolt port 2 bridge for PCIe communication -> multiple buses


I have a UPD2018 that won’t work with a pluggable USB-C to VGA, what is the issue?


I replied in the VGA adapter thread. Aside from making sure you connect the usbc-vga adapter to the correct USB-C port, you should also ensure that there’s a snap or click indicating that the USB-C connector is fully inserted.

I have a USB-A to USB-C adapter that requires slightly more force to make sure it’s inserted all the way. I might consider filing off half a millimeter of plastic from the adapter so it inserts better…


Using an IT-GO “ADP-099-31” fixes the startup problem. See…