Protocol trigger for Atorch electronic loads

A quick look at a handy little gadget. I bought a few to have on hand, and maybe I’ll include one with one of the new loads.

To stay up to date with new posts on the blog, I recommend following me on Instagram. I’ll post notifications about all new posts there, and might also write about something interesting from time to time: link to my account

You can also subscribe to updates and new articles on the Telegram channel - https://t.me/KirichBlog

A quick question unrelated to the review. Lately, I’ve occasionally been getting questions about buying an electronic load in the comments on my YouTube videos. The question is always the same: how can I get in touch with you? The answer is just as predictable: there’s an email address in the YouTube and blog contact info, so you can write to me there. But every time, I never hear back. Is this some kind of trend, or am I missing something?
And since I’ve gone off topic, a reminder: if you’ve written to me and haven’t received a reply, check your spam folder first. If there’s nothing there, try asking again. I usually reply to about 90% of messages (regardless of where they come from), but sometimes I forget. For example, I’m going through my email and see a question. I’m 100% sure I replied—I even remember exactly what I said—but the message is still marked as "unread". How that happens, I don’t know. I often see this too: someone asks something, I reply, and then… silence. No idea whether they got my reply or not...

Anyway, back to the subject of the review.
Recently I spotted a neat little gadget in the Atorch store: a protocol trigger, or a "cheater", if you prefer. Basically, it’s a device that can send a command to a power supply (a so-called "charger") to make it output a voltage other than its default setting.

This kind of gadget often comes in handy when testing PD and QC power supplies and power banks. I usually use a USB tester for this, but connecting a load to it wasn’t very convenient, especially when I needed accurate measurements. I had to rig something up.

I ordered several at once—coupons, discounts, you know how it goes.


Atorch often includes an adapter board with its loads, but those just have connectors. This one clearly has some electronics on it, and the board is noticeably larger too.


1. The board has a pair of buttons and a bunch of LEDs.
2. Nothing interesting on the underside.
3. The connectors are the same as on the basic adapter boards. The only difference is that the DC jack is noticeably better quality. It’s a 5521, by the way.
4. It connects to the load the same way, using four contacts. Since this is a four-wire connection, it’s easy to fit longer wires to the board and improve measurement accuracy when the board needs to be placed farther from the load. There is one catch, though: the 24MP and 24EW series loads are currently three-wire in practice, and I have to convert the ones I build to four-wire.



Here’s what’s what on the board.
At the bottom are two buttons, minus and plus. The first cycles through the protocols toward lower voltages, and the second toward higher voltages. Hold either button for a couple of seconds and the protocols start cycling automatically. They cycle in a loop. If a voltage isn’t supported, that step isn’t skipped; nothing happens.
Above the buttons are LEDs indicating the selected voltage: 5, 9, 12, 15, 20, and 28 V.
Above the voltage LEDs is an LED that indicates a command is being sent. It flashes when you press the buttons.
To the right is a power indicator LED. It’s simply connected to the board’s output contacts.
There’s another LED in the center of the board, but I haven’t figured out what it does.


There are three chips on the board: a voltage regulator on the left, a microcontroller at the top, and most likely a PD chip at the bottom.

I don’t remember whether this is mentioned in the description, but I think it’s important. The thing is, the board has a DC5521 connector, and since it also has a voltage regulator and everything is connected to the same power rail, I wouldn't apply more than 30 V to this connector. I think that would end with buying a new board, so keep that in mind!!!



Board dimensions. You can see that it was designed specifically to fit the standard screw terminal used on Atorch loads.


I'll test it with an Atorch DL24EW load. I could have used a 24MP, or any other model they make, but there's no difference.


Four protocols are supported:
Power Delivery in two versions
Quick Charge
Samsung AFC
Huawei FCP

But to me, the first two are the most interesting, especially PD 3.1. I don't have any power sources that support it, though.


First I test it with a small power bank, then with the one I sometimes build. The first one delivered a maximum of 12 V over both USB-C and USB-A, while mine delivered 20 V over USB-C.
I have a DC-DC board somewhere that supports QC at 20 V, but in practice that's extremely rare. So if you have USB-A, you'll usually get a maximum of 12 V.


I connected it to some power supply, and besides the default voltage, it was also able to output 9, 12, 15, and 20 V.


Here's the charger from my old phone, and there are some quirks here, just like with the phone itself. If I connect it through the trigger I'm reviewing, I get only 5 V.


1. If you check the protocols with a tester, nothing interesting shows up.
2. But if you connect a smartphone, the tester shows that the voltage first goes to 5, then 7, 9, and 12 V, while indicating QC protocol.
3. My power bank also delivers a maximum of 5 V.
4. But a simpler one can charge at the full 12 V.

The point is that the phone most likely charges using the MTK protocol (the 7 V reading is a clue, since typical QC 2.0 goes straight from 5 to 9 V). In practice, not all chargers support it. You can read more about protocols here.


And finally, a few notes on how the controls work.
As I mentioned, a short press increases or decreases the voltage by one step, while a long press starts cycling continuously through all the modes.
The trigger also remembers the last mode, including automatic mode. So if you use it, turn the power off, and then turn it back on, automatic mode will be activated again.

The mode where the trigger tries to request a voltage the charger can't provide works in a more interesting way.
Set it to 20 V, and the power bank outputs 20 V.
Turn it off and connect it to another power bank: it outputs the maximum that one can provide, 12 V.
Connect it to the first power bank again, and it outputs 20 V.

In other words, the tester remembers the selected mode. If you connect something that can't provide that voltage, it outputs whatever it can, and the indicator LEDs show this. But the operating mode itself isn't canceled, so the next time you connect a device that can provide a higher voltage, it will switch to the originally selected setting.

Overall, it's convenient to solder to, but you need to remember how the whole thing works.


To sum up, this is definitely a genuinely useful and convenient device. Sure, it doesn't support every protocol, as my phone's charger demonstrates, but that's rare. And the claimed support for PD 3.1 (which I think it really does support) and voltages up to 28 V are genuinely useful.

Overall, it's inexpensive, neatly assembled, and it works. What more could you ask for? :) The only downside is that shipping costs extra, so it's better to split an order with someone or add it to other items from this store.