MacBook Pro (Retina, 13-inch, Early 2015) Thunderbolt 2 port for small second display (ASUS MB169C+ Portable USB Monitor for eg)

can I get a bidirectional adapter like the Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter? I believe the thunderbolt port puts out 9.9 W max and this display Power Consumption(Typical):<7.5W* *measuring a screen brightness of 200 nits without audio/ USB/ Card reader connection)

basically I need a second portable screen 13" - 15" preferably type C like a large variety of modern displays available as mentioned above, preferably powered from the adapted thunderbolt 2 port etc, that way when I update the Macbook Pro later the screen will be usable on any updated model with Thunderbolt 3...

It doesn't have to be the above mentioned Asus screen but it looks the goods and no less then 1920x1080. I am not against the idea of utilizing the two thunderbolt ports one for display and one to power said display if required OR even use the HDMI port etc... just as long as it works and powered by the Macbooks ports as the Macbook can be running from the wall charger as required...

Again a portable setup preferably single cable. recommendations and ideas much appreciated.

2 Answers 2


No. This will not work. You will need to get a display with its own power supply.

Thunderbolt 1/2 doesn’t support power delivery. Even though Thunderbolt 3 does, connecting an adapter doesn’t magically make power appear.

The (up-to) 9W of power is bus power - you can’t assume that because it’s there, it can be utilized, especially to power a device. Remember, Thunderbolt can support up to 6 devices, so it wouldn’t make sense that a single device allocate most or all of the bus power.

  • This is actually for my girlfriend and not my every day machine. Turns out I over cooked this plan a little bit and didn't realise this Mac intact has USB3.0 and it will be as simple as buying a USB3.0 monitor. I've found a few models that will work. Isn't future proof in the way of being type C and of lessor quality being older model but It is also 1/3 of the price of newer models.... it's still a win even if lower res etc, it's mostly going to be us2d in portrait position text etc so it's not a problem really Thanks mate.
    – Elosee
    Commented May 5, 2019 at 22:51

I agree with other answers that this will not work but for a different reason. A Thunderbolt adapter will not work because this is not a Thunderbolt device. This is a DisplayPort device. To get video to this display means using a DisplayPort cable. Because DisplayPort does not provide power to the device this display will not work with a mini-DP to USB-C cable. DisplayPort specifies that both the source and sink are to supply power to the cable. https://en.wikipedia.org/wiki/DisplayPort#DP_PWR_(pin_20) This is so that there is power for active or amplified cables.

What should work is a Thunderbolt dock. A common Thunderbolt 3 dock should work so long as it provide the necessary 7.5 watts on a downstream USB-C port that supports USB and DP. The upstream port will be USB-C as well but a TB2 to TB3 adapter to the laptop will provide the necessary connection.

In reading reviews of people using TB3 docks with TB2 hosts the downstream USB ports will still work as it seems every TB3 dock has a USB controller in them.

This is not a low cost solution and so I don't expect people to just run out to buy a TB3 dock to plug in a portable USB-C display. For those that already have a dock this is a workable solution. There may be another similar case that this information is helpful.

This is an educated guess, I have not tried this myself, so if there is someone that tried this and it does not work then I'd appreciate feedback.

I realize this is an old question and a resolution has been found but this question popped up and I thought I'd offer an alternative to those with a similar problem.

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