[CentyLab]’s PocketPD isn’t just adorably tiny — it also boasts some pretty useful features. It offers a lightweight way to get a precisely adjustable output of 0 to 20 V at up to 5 A with banana jack output, integrating a rotary encoder and OLED display for ease of use.
PocketPD leverages USB-C Power Delivery (PD), a technology with capabilities our own [Arya Voronova] has summarized nicely. In particular, PocketPD makes use of the Programmable Power Supply (PPS) functionality to precisely set and control voltage and current. Doing this does require a compatible USB-C charger or power bank, but that’s not too big of an ask these days.
Even if an attached charger doesn’t support PPS, PocketPD can still be useful. The device interrogates the attached charger on every bootup, and displays available options. By default PocketPD selects the first available 5 V output mode with chargers that don’t support PPS.
The latest hardware version is still in development and the GitHub repository has all the firmware, which is aimed at making it easy to modify or customize. Interested in some hardware? There’s a pre-launch crowdfunding campaign you can watch.
This is very nice,and it might become my next portable power supply.
I have an AliExpress special ATX power supply breakout board that I’ve been using.
What I think would be neat is it those ATX breakouts actually had PD functionality it’s got to be the cheapest way to have a 650W PD power supply?
I suppose that’s actually this in reverse to some extent.
The PD standard doesn’t support that much current. The maximum is currently 48V5A, 240W.
I meant via multiple channels! But noted.
Even trying to fast charge to modern smartphones puts PD supplies into eye wateringly expensive territory.
I think I got a 100W usb-pd supply for $20 lately? And 90w a couple years ago for under $40. Regardless I would feel bad for the battery in any phone-sized device I was charging at anywhere near that sort of rate.
Server power supplies off ebay are probably the most inexpensive $/Watt
Working with ATX supplies is a pain, in my experience. I’m always hitting over-current limits.
Great point! And I suspect smaller than my current full size ATX PSU as well as perhaps being longer living.
Will be louder though
What’s the yellow component? Maybe a USB port but I can’t see a picture from that side.
It’s an XT60
Right angle Xt60 connector
Pro-tip folks, if you want a higher power (65W/100W) mains adaptor for charging your phone or whatever, you are better off buying a newer USB laptop charger than a wall wart.
The laptop chargers are more durable since they have more thermal headroom because of their bulky size
Be careful with this. Some laptop chargers get lazy about the full USB PD spec. In particular I’ve seen Dell chargers that offer 5v and 20v and nothing else. So any device that can’t handle 20v, a lot of phones fast charge at 9v, will have to fall back to slow charging at 5v.
it’s generally pretty old (5 or more years old) PD chargers that do this – it’s going to be damn hard to find a new USB-C PD PSU that only offers 20V and 5V! That’s in large part because, for a while now, it’s simply been cheaper to do it the proper way.
IIRC this is actually a dell-specific problem; I heard that their laptop chargers are mutually screwy with regards to regular usb-pd stuff, even things like other laptops that are also going to always pick 20V. I can’t remember specifically, but there were some bad reviews on an aftermarket power adapter to that effect.
I did way Better with this cheap and smaller device
0,6-36v 5A output.. Just add a 3d print case and 2 banana jacks.
https://www.amazon.it/Hsthe-Sea-convertitore-Alimentazione-Step-up-Down/dp/B0BP79YKJX?pd_rd_w=qBqNo&content-id=amzn1.sym.cdc0bdeb-67cc-4bd0-85aa-1d2b5b82cd20&pf_rd_p=cdc0bdeb-67cc-4bd0-85aa-1d2b5b82cd20&pf_rd_r=W7DTYT3B5A1CJ342GTQ5&pd_rd_wg=pRBvO&pd_rd_r=49ab9b68-f659-45c3-a92b-66ff776c4fca&pd_rd_i=B0BP79YKJX&psc=1&ref_=pd_basp_m_rpt_ba_s_4_sc
Nice but it does not beat my cheap but good FNIRSI DPS-150
ono said: “Nice but it does not beat my cheap but good FNIRSI DPS-150”
Maybe this beats your FNIRSI DPS-150? These $79 each stand-alone Hanmatek benchtop power supplies are Modbus over USB programmable and come in two versions: 0-30VDC @ 10A max., and 0-60VDC @ 5A max.
https://www.amazon.com/dp/B08TZVZQR6/
Modbus:
https://en.wikipedia.org/wiki/Modbus
This reminds me of the ISDT 608PD, which you can find on Amazon for $30 (and is on my wishlist, so I can’t truly compare).
I have an older ISDT charger paired with a homemade PD to XT60 adapter(Now I’d probably just buy one) that generally takes the place of a bench supply for me.
Granted I’m not an electric engineer, but this defies my understanding of physics: how can that deliver 100W? Tiny caps, no coils, no heatsink? Even my DPS-5005 looks big in comparison. Is that using a super-duper IC recently released?
The power comes from a separate USB-C power supply, this bit just requests the desired voltage and current. Centilab is also working on a USB PD3.1 module with rpi pico layout. That one will be able to get the full 50V 5A from the newer supplies.
That device is not the power supply, it simply communicates with the power supply you plug in through usb c. For normal bench power supply usage, varying the voltage and amperage. You’d need a charger that supports PPS which allows it to control the amperage and voltage otherwise I think you’re stuck with the default usb c charging ranges, i.e. 5v, 9v, 12v, etc… even still, seems to be pretty tiny including the charger bulk.
quite doable really, just think about the insane amount of amps modern drones can draw via their motor controllers, most of which these days occur on a single package die
This device isn’t really the power supply, rather it is acting as a brain for a USB-C charger (or battery bank) that supports the “Programmable Power Supply” (PPS) functionality. PPS allows for the USB-C power supply device to adjust the voltage and current supplied as demanded by the receiving device. This little brain box then passes that through to whatever its actually plugged in to, with the USB-C device being none the wiser. If the USB-C device only supports PD mode instead of PPS then this box can only output 5/9/15/20V.
Because as far as I can see it’s basically requesting the nearest power delivery voltage from a pd spec external power supply and then just bucking a little bit to the exact requested voltage and doing some current limiting. Everything you mentioned for the heavy power portion of the circuitry (big caps/coils/conductors/heatsinks) is already inside the external pd supply.
PPS provides the ability to specify output far more precisely than the older PD profiles can (down to 0.2V granularity), there is absolutely no extra buck stage in this device.
Nice so even simpler than I thought!
this isn’t really a power supply?? more like a handy interface for USB-PD? i mean, that’s handy, but the power supply is purchased separately, and then you are at the mercy of its specific characteristics.
i looked for but failed to find the schematic so i’m sorry if i’m missing something but it looks like it doesn’t have any voltage or current limit, like the power rails are just pass through?? so like i do have a cheap bench supply and my favorite feature is that its current limit is really robustly designed, as if they expect the user to draw a steady current at the limit. but as far as i understand it, usb-pd overcurrent protection is just for safety / durability. i think if you bump into it, won’t most chargers glitch out in some way?
and the one complaint i have about my bench supply is that its output is noisy af. a lot of little spikes that are generally too small for me to care about but also WAAAY too large to be filtered out by the electrolytic capacitors i keep on my bench. i can’t imagine many usb-pd wall warts are optimized for this kind of purpose even as well as a cheap bench supply is?
of course once i get a usb-c supply that does more than proprietary cellphone fast charging and the obligatory 5V old school USB compatibility mode, i imagine i’ll start to feel differently about it. are we at that point where you can buy a USB-C power brick and support a meaningful subset of USB-PD without specifically shopping for the one model that does it? am i just out of date?
I don’t know much about it but this device really seems to hinge on a PPS usb c charger. PPS is programmable Power Supply and the chargers that support it supposedly have at least some granularity in controlling voltage and amperage over usb c.
Devices calling themselves a “USB-C interface” tend to be a literal interface to USB-C power delivery only. That is you select one of the USB-C PD voltages and run with it.
This claims to give a regulated voltage anywhere between 0-20v. It even shows 12.8v selected, which is not a standard USB-C PD voltage. It is requesting a higher 15v (or 20v) from USB and regulating it down to 12.8v
Also not sure why you say it looks like no voltage/current limit. The image with the screen on is clearly showing the set limits. It even shows a constant voltage/constant current setting with CV selected.
I would say you are a bit out of date, but not by much.
The premise of this project is that by using a USB-C PD supply, you are overtly not “at the mercy of its specific characteristics”
There are much simpler devices you can buy that are literal “USB-C PD Interfaces”, where you set a DIP switch to 5, 9, 12, 15, or 20 volt and the interface negotiates for it if it’s available. These are $1-2 ICs. The device that is the subject of this article would use one of these interfaces, but also provide buck/boost functionality to dial-in voltages between the supplied PD voltages.
You’re significantly behind the times – a modern USB PD supply with PPS gives fine control of the voltage and current limit settings, down to 0.2V steps. The entire point is to eliminate the need for extra hardware to provide “buck/boost functionality to dial in voltage between the PD [profiles]”.
This device is purely providing the user interface and breakout.
The whole point of PPS is to offload CC/CV charging from the device to the USB power supply, so riding the current limit is central functionality, and should be quite well-behaved.
But I agree with you regarding noise — if you’re exploiting gadgets made for charging Li-ion batteries, the best you can reasonably hope for is “good enough for charging batteries”.
You could make a proper bench power supply that leverages PD/PPS to provide minimal overhead voltage for a linear regulator, but of course that won’t fit in your pocket anymore.
neat! thanks! that does answer my concern — i find it hard to imagine they would offload the constant current charging from the device to the brick…but if they did, that’s what it’d take!
I like a PSU with heft. Stop it being dragged about by the leads. As a PSU front-end, this does look quite nice tho.
The problem with a design like this is the low voltages or currents:
The device itself needs to run it’s controller, OLED screen and so on. And since there is no separate power supply for this, this power needs to come from the same USB-PD connection as the output. So you can’t have it output for example 1.8V, because the controller and screen usually needs more to run.
You could overcome this problem by dividing the output into two paths and use a voltage regulator in the power supply itself once you go below certain values instead of the USB-PD PPS. But this complicates the circuit of course.
Can a PD PPS supply be asked to provide less than 3.3V?
In any case, a linear regulator as a final output would be a good idea anyway, for lower noise and higher control bandwidth.
I don’t think PD PPS will work with less than 3.3V. But PD is complicated and I don’t consider myself an expert on this topic.
A linear postregulator might be good for lower noise. But a linear regulator always has voltage drop you now have to account for and also an analog control loop you have to build in a way that it doesn’t oscillate. Also heat to dissipate. So more analog complexity, parts and size.
For all my ham radio gear, I have configured Anderson power connectors. Even the low power stuff.
While some have USB as well, none have banana plugs. That means adding an adapter to this power adapter, or breaking it open the minute I buy it.
Well, that would be a “hack” I suppose.
I like using the Riden power modules (RK6006) ($29USD AliExpress or more bought locally) that takes any power supply. Haven’t tried it yet, but this project got me thinking of using it with a USB-PD + trigger board.
Many modern RC battery chargers can also function as an adjustable power supply. Well, not technically the power supply, but they run off a PD power supply or other DC input via XT60 and can provide variable DC voltage out.
The SkyRC B6Neo is one example.
I bought a couple of those power supply boards and they are quite nice. They also work with some usb battery packs