PocketPD It's a great little idea: a bench power supply Powered by USB-C and literally fitting in your pocket, it's designed to go with you anywhere without sacrificing fine-tuning of voltage and current. It began as an open-source project after a long process of iterations, refining both the hardware and firmware with community help to get the most out of the USB Power Delivery standard and, in particular, to PPS mode (Programmable Power Supply).
With a modern charger or a compatible power bank, this power “requester” It negotiates the best possible profile and gives you a fully adjustable output, with integrated protections and a clear interface based on an OLED screen and physical controls. No complicated frills: buttons, encoder and real-time data reading to do what you need without distractions.
What is PocketPD and why is it different?
The key to PocketPD is that it doesn't have buck/boost converters on the board: directly leverages the PPS negotiation USB-C is used to request the desired voltage and current from the charger. This allows for a lighter and more compact design, with less power loss and less heat, ideal as a portable power supply or for bench testing when you need to diagnose problems in the field. Furthermore, acts as a PD 3.0 profile testerwhich makes it a doubly useful tool for those who work with USB-C.
Its philosophy of use is pragmatic: if you connect a modern charger or battery with PPS (many from popular brands like Anker, Ugreen or Baseus (they already support it), the device lets you request precise voltage and current values. And if PPS is not available, The firmware falls gracefully to a standard 5V (PDO) profile and allows you to adjust the profile with a long press of the Volt/Amp button to maintain utility in almost any scenario.
The role of PPS within USB Power Delivery
Mode Programmable power supply It was introduced with USB PD 3.0 to fine-tune battery charging by reducing conversion losses. In practice, PPS allows the consuming device to request the exact voltage and current limit it needs from the source. adjusting the values in very fine stepsThus, with PocketPD you can behave like a real bank source, regulating parameters with ease and without adding unnecessary conversion stages.
An important note: actual capacity depends on every link in the chain. The final power is limited by the weakest component.For example, if your charger delivers 5 A but the cable is only certified for 3 A, the system will not exceed 3 A. Similarly, the PPS voltage range varies depending on the charger: The usual values are 3,3–11 V or 3,3–21 VAnd PocketPD adapts to what each source negotiates.
Output ranges, CV/CC modes, and adjustment granularity
With a compatible power supply, you can adjust the voltage from 3,3V up to the maximum allowed by the charger (typically 20–21V). 20 mV stepsa level of control typical of laboratory power supplies. For current, the configurable limit starts at 1 A and rises to the available PPS maximum. 50 mA steps, perfect for protecting sensitive prototypes or keeping tests within safe margins.
It is worth highlighting a particular feature of PPS mode in this project: Current limitation below 1 A is not supported in DC when working in PPS. If you need to test very low loads with fine current control, you will have to consider this restriction in your testing methodology to avoid surprises.
Compatible with chargers, power banks and car
PocketPD's versatility is evident in its feeding: It supports USB-C inputs between 3,3 and 21 V and up to 5 AThis opens the door to working with wall chargers, power banks, and car chargers. In field scenarios, carrying a PPS power bank in your backpack solves many problems without depending on the electrical grid, and in the workshop, a good PD charger will give you the necessary headroom for more demanding tests.
If you have any doubts about compatibility, it's best to check the charger's specifications: that mentions PD 3.0 (or later) with PPSChargers without PPS will continue to function with a 5V PDO profile, but you will lose the continuous voltage adjustment. And don't forget: Use certified cables For the intensity you need; it's a classic case of the cable being the bottleneck of the system and limiting you without you even realizing it.
Display, controls, and profile memory
The interface is resolved with a 0,96 ″ OLED display It offers clear voltage, current, and status readings, and features physical controls (encoder and buttons) for straightforward parameter navigation. It's simple to use, with immediate response and no complicated menus, which is a big plus when you're measuring and don't want to waste time.
A practical detail: the selected profile (voltage and current limit) It's saved in the microcontroller's flash memory and retrieved upon reboot. This means you can turn off, turn back on, and pick up right where you left off—something that, in everyday use, is more appreciated than you might think.
Internal architecture and electronics
At the heart of the system is a Raspberry Pi RP2040 (Cortex-M0+) with 16 MB of QSPI flash memory, responsible for logic, UI, and negotiation control. A USB PD protocol processor is used as the brain of the USB PD protocol. AP33772 sump controller, which handles the dialogue with the loader to fine-tune the PPS parameters with precision and reliability.
For power routing and measurements, the design integrates current and voltage sensor onboard and a 5 A (23 V max.) “ideal diode” type load switch, which reduces voltage drops and improves efficiency. This approach, combined with the absence of DC-DC converters on the board, minimizes heat and simplifies the path between the source and your circuit under test.
Protections and security
Since it's a power supply usable in prototypes and sensitive electronics, protections were essential. At the input, there are TVS/ESD on DC, USB 2.0 and VBUS to cover peaks and discharges; and the output, TVS/ESD on VOUT along with flyback diode protection For inductive loads, in addition to protection against short circuits, reverse current, and, in documented versions, also reverse voltage on the rail.
Overall, the security system is designed so that minor errors won't ruin your session or damage your hardware. Even so, the manufacturer's recommendation is clear: Respect the limits of your charger, cable, and the PocketPD itself.and always validate the configuration before connecting sensitive loads.
Physical design, assembly and dissipation
The chassis and the encoder knob are 3D printed Made with high-temperature material (PETG in the documented versions), it performs well in hot summer weather or under demanding test benches. The design prioritizes simplicity and the repairability typical of the maker world.
One interesting feature is the magnet integrated into the back: It is used to attach it to metal surfaces. (like a bank teller bar) and, incidentally, acts as passive heat sinkhelping to dissipate heat during prolonged use. This simple feature is very useful in workshops and laboratories where you need to have the power source readily available and clearly visible.
Output connectivity and variants
As standard, PocketPD comes with pre-soldered banana terminalsready for use with standard instruments. Two variants are also offered: one with a block detachable screw added, and another that includes two additional unsoldered connectors so you can choose the one you prefer: Anderson Powerpole PP15/45 o XT60It's a flexible way to adapt it to your ecosystem without forcing you to a single standard.
Please note that, as specified, All exits share the same rail internal; that is, they are not independent channels. This is important when trying to avoid simultaneous connections that could introduce unwanted feedback or unhygienic ground loops.
Key specs
For those who want to get straight to the point, here's a technical summary of the most relevant points. Remember that the maximum negotiable tension It depends on your PPS charger and the current is limited by the weakest element in the chain (charger/cable):
- Entrada: USB Type-C3,3–21 V up to 5 A
- Starting Line: 3,3–20/21 V up to 5 A (depending on available PPS)
- Modes: CV (20 mV/step) and CC (50 mA/step, minimum 1 A in PPS)
- Screen: 0,96″ OLED
- MCU: RP2040 + 16 MB QSPI
- IC protocol: AP33772 (PD sink)
- Protections: short circuit, reverse current, TVS/ESDflyback; variants include reverse voltage
- Dimensions 86 × 55 × 21 mm; weight: 63 g
Regarding the operating temperature, there are references to two ranges in different technical notes: 0–80 ºC y 0–45 ºCIf you're going to stress it near the upper limit, lean it on the magnet/heat sink and monitor the surroundings to maintain reasonable margins.
Truly open source: firmware, hardware, and casing
The software portion is published under MIT licensecombining custom libraries and third-party community resources. The schematic and PCB were developed in KiCad 9.x and will be released under CC BY-SA 4.0While the 3D-printed case is also available for you to customize to your liking. That is to say, You can study, modify, and contribute both to the code and to electronics and mechanics.
If you'd like to learn more about PPS, there are references in the community to content from GreatScott! and ElectricArc240These are very useful for understanding the fundamentals and leveraging them in your own projects. The repository also includes... Gerber files and firmware Ready for you to build a unit yourself if you're into DIY.
Field use and professional profile
The team behind PocketPD comes from the world of remote sensing and field instrumentation. That background explains design decisions such as opts for physical controlsclear readability, a rear magnet, and a compact body that, without boasting, It works when you need it to.Whether you're a professional, an engineering student, or a maker, this is a versatile tool that won't take up much space in your backpack.
Another plus is that PocketPD also acts as PD profile testerThis is useful for validating chargers and cables and verifying what you're negotiating in each case. This dual power supply/tester functionality is especially practical in teaching labs and maintenance kits, where time is of the essence and you don't want to carry half a shelf of equipment.
Manufacturing, quality control and materials
Production and assembly are handled by ElectrowSpecialists in agile print runs have accelerated development through multiple iterations. Each unit undergoes funcionality test before leaving to ensure that it arrives in perfect condition from the factory, something that, when we talk about a power supply, is noticeable from the first use.
The packaging has sought to reduce waste without sacrificing protection. avoiding excess foamThe casing and knob are 3D printed with high-temperature filament to withstand warm environments and long sessions, a practical and sustainable decision in line with the open spirit.
Logistics and availability
After each manufacturing batch, shipments are routed through Crowd Supply's fulfillment partner, Mouser Electronicsfor global distribution. If you're interested in following the latest news, the team has announced an improved version and share progress and updates through the project's channels so you don't miss anything.
Project maturity, risks and evolution
The design has gone through several rounds to guarantee robustness and reliabilityThe core functionality has been stable for some time, and firmware updates focus on control improvements and user experience. Regarding supply, there is a flexible bill of materials that reduces the impact of potential stock shortages in key components.
As with any electronic product, There is always some risk.However, preventative measures have been taken here, and it has been validated with a successful pre-production run. At the user level, the biggest real “risk” is pairing it with an incompatible charger/cable; that's why we emphasize: Choose the right power supply and cable to enjoy its full potential.
PPS, PD and Quick Charge: clarifying concepts
Within the zoo of load standards, PD and QC are the best known. USB Power Delivery It's the umbrella that allows high power outputs in USB-C (up to 100W in classic revisions), with predefined profiles and, since PD 3.0, the mode PPS for fine-tuning. Instead, Quick Charge (Qualcomm) is a proprietary fast-charging technology for mobile phones; recent versions have improved PD compatibility, but their focus is not on acting as a power bank.
The advantage of PPS over fixed profiles lies in reduce losses and heat by requesting exactly what is needed at any given moment. For batteries, this means less thermal stress and longer lifespan; for a tool like the PocketPD, means fine pitch control without inserting additional converters that complicate the set.
Compatibility tips and equipment that supports PPS
There are increasingly more chargers and power banks with PPS on the market. In addition to those already mentioned from Anker, Ugreen, or Baseus, several high-end smartphones (such as recent Samsung Galaxy models) and modern laptops support it, which helps charger manufacturers include the mode in their devices. Even so, Always check the technical specifications. to make sure you have the 3,3–11 V or 3,3–21 V range you are interested in and the necessary current.
If you connect a non-PPS source, PocketPD will switch to 5V PDOYou can work with 5V loads and adjust available profiles, but you'll lose the magic of dynamic voltage adjustment. It's perfectly usable for 5V electronics, but if your goal is regular between 3,3 and 20/21 V In 20 mV steps, you will definitely need PPS.
Just to avoid confusion: GPD Pocket is not PocketPD
On the web you will see references to GPD PocketIt's a 7-inch mini-laptop with Windows 10, an Atom x7 processor, 8 GB of RAM, eMMC storage, WiFi-AC, and USB-A/C and microHDMI ports. It's an interesting device in terms of size and design, but It is not related to PocketPD Beyond the name game, if you're looking for a programmable USB-C power supply with PPS, focus on the PocketPD; if you want a mini-computer, then yes, the GPD Pocket is a different story.
That laptop, by the way, stands out for its alloy chassis, 1920×1200 IPS touchscreen, 7000 mAh battery, and a compact keyboard with trackpoint, but It has nothing to do with it with the functions of power supply, protections or PD negotiation that concern us here.
PocketPD combines fine voltage and current control via PPS, comprehensive protections, a clear interface, flexible connectivity, and an open-source approach that encourages learning, modification, and improvement. With a compatible USB-C PD 3.0+ charger/cable, You carry a bank fountain in your pocket Ready for laboratory, classes or fieldwork, with the peace of mind of careful manufacturing and a community that pushes the project forward.
