Emulator for controlling a QC/PD power supply

This device is more commonly called a trigger, although that’s not quite accurate—it’s just what the name has become. I decided to order one mostly on principle, just to have it. And since I’ve got it now, why not test it and show what it’s all about?

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These devices come in several versions:
as a separate board
built into a cable
built into an adapter from USB to various types of plugs.

The first type usually lets you adjust the settings, while the second and third do not. Though if I remember correctly, there were also cables with software-configurable operating modes—but don’t quote me on that.

It’s inexpensive, and I thought it might come in handy, but it turned out to be nowhere near as good as I’d hoped.

I ordered it along with a few other boards, and some time later received it in an antistatic bag.


There are two versions for sale, differing in how they connect to the power supply: one has a plug, the other a socket. The plug version suited me better.

Description from the product page
Features:
1). Supports PD3.0 and PD2.0 voltage trigger output, with freely selectable modes.
2). Has a key-lock function to prevent accidental operation.
3). Has an output LED indicator to show the operating status.
4). Settings are saved automatically, and the last setting is restored when power is turned on again.
5). Ultra-low power consumption, supports output up to 100 W.

Specifications:
1). Product name: PD2.0/3.0 trigger
2). Input voltage: 5 V DC
3). Trigger output voltages: 5 V > 9 V > 12 V > 15 V > 20 V
4). Maximum output voltage: 20 V
5). Maximum output current: 5 A
6) Operating temperature: -25 ℃ to 85 ℃
7) Operating humidity: 5% to 95% RH
8). Dimensions: 44*20*15 mm



There’s a USB-C plug on one end and USB-C and USB-A sockets on the other. They’ve also put a quick reference guide for switching modes right here.


The board supports both connector configurations. It has a pair of buttons for control and a small LED to indicate when it’s on.


Dimensions from the product page


At first I wanted to use a PD power supply for the test, but a few “complications” came up, so I had to use a converter board instead.


In this case, I used a ZC826 board. One of its key features is support for QC at 20 V, along with the ability to step the voltage up or down and operate as a power bank with battery charging.


Before the tests, here’s a quote from the product page describing how to operate this board.

In reality, things turned out a little... differently.

First, starting up at a fixed voltage.
1. 9 V when powering on while holding S-
2. 12 V when powering on while holding S+
3. 20 V when powering on while holding S- and S+
4. 5 V if, while powered on, you hold S+ and press S-.

This all matches what is printed on the board. Note that the voltages you get may differ—for example, instead of 12 V, you might get 12.2 or 11.9. This is determined not by the board, but by the settings on your power supply.


You can adjust the voltage in 0.2 V steps (QC3.0 protocol) using the S- and S+ buttons. To enter adjustment mode, first hold S+ and press S- to reset the voltage to 5 V.

1. The lowest I could set it was 3.66 V, but that's the converter's output limit.
2–4. The adjustment works fine; no issues


You can also adjust the voltage in 1 V increments. To do this, first reset it (hold S+ and press S-), then hold S- and press S+ to adjust the voltage.
Everything works fine, but there's a catch: sometimes it mistakenly registers a long press as a short one, so the voltage changes like this, for example: +1, +1, -0.2, +1, +1.


When power is disconnected, it remembers the last state and activates it on startup. Convenient on the one hand, but on the other, you could accidentally fry your load.


As an extra check, I measured the current draw. It turned out to be the same at both 5 V and 20 V: 3.4 mA.


I would probably praise this device now, since it can change the voltage from the minimum all the way up to 20 V, if it weren't for one big “BUT.”
The description said it supports PD, but no matter how hard I tried, I couldn't get it to work properly with a PD power supply.
Of course, you'll ask: so what's the “catch”? Let me explain.
Power Delivery power supplies often have a 20 V mode, and sometimes can even deliver 5 A in that mode, giving us up to 100 W of power.
But even a 100 W PD power supply can't always output 20 V in Quick Charge mode. That's what happened in my case, which is why I tested it with a board that supports QC at 20 V.

My Choetech PD6008 power supply can output 20 V at 5 A, but in QC mode it only outputs 12 V, which is what I got.

I tried a whole bunch of options, following the instructions and just trying different combinations, but the tester only occasionally displayed PD MTK mode. Most of the time it showed QC 2.0/3.0 or even Samsung 12V, and I never got 20 V from a PD power supply.
I did get 20 V with a converter board, of course, but boards like that are extremely rare, and finding a power supply that supports QC 20 is even harder.
Later, I noticed the board's marking: LX-QC03-V2. Something tells me the QC letters in the model number are there for a reason.


So, in conclusion: the board works fine, but only supports QC. Since power supplies that support QC at 20 V are uncommon, the output voltage will be limited to 12 V.

That's all from me. I hope this was useful. If anyone knows how to get this board to work in PD mode, I'd be very grateful.