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With this WUZHI module, you can convert the 5 Vdc from a USB charger into an adjustable supply voltage of up to 30 V for powering small circuits. |
Introducing the ZK-DP3D from WUZHI
An adjustable power supply from a USB charger
This module is ideal for powering small experimental circuits without the need for a large, heavy laboratory power supply nearby. The ZK-DP3D can be connected to any USB charger. The device converts the 5 Vdc voltage from the charger into a supply voltage ranging from 1.00 V to 30.0 V. The maximum current output can, at least in theory, be set between 10 mA and 2,000 A. In theory, because no cheap USB charger is capable of delivering such power.
However, the ZK-DP3D does support various fast-charging protocols used by modern chargers that are capable of delivering higher voltages and currents than the standard cheap USB chargers you can buy for a few euros.
Powering circuits from a power bank
A typical example of the usefulness of this little device is when you have a circuit that, for whatever reason, needs to be powered completely independently of the mains. You can use a power bank, but most only supply 5 Vdc. By connecting the ZK-DP3D to such a power bank and setting the output voltage to, for example, 15 Vdc, you can still power your circuit completely independently of the mains.
The appearance of the ZK-DP3D
The photo below shows what this device looks like. It is eight centimetres long, four centimetres wide and two centimetres thick. It weighs just under forty grams. On the left-hand side are three USB connectors for the input voltage: USB-A, micro-USB and USB-C. On the right-hand side, you'll find two spring-loaded terminal blocks (Wago terminals) from which the output voltage is available. On the top, to the right, there is a female USB output, but there's a catch – read on.
On the underside, on the left, there is an extremely small 'ON/OFF' push-button and, on the right, a three-position 'SET/M' switch which you can use to configure the device. Finally, on the front panel, three LEDs indicate the power supply's status.
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| The appearance of the ZK-DP3D. (© AliExpress) |
PLEASE NOTE!
Although the female USB-A connector in the top right-hand corner of the module may feature the familiar USB logo, it is NOT a standard USB output! This connector is set to the module's output voltage and is therefore not 5.0 Vdc.
Manufacturer, suppliers and prices
It is not possible to identify the manufacturer of the ZK-DP3D with 100 % certainty. It appears to originate from a company in Shenzhen operating under the name 'Shenzhen ZK Electric Technology Co., Ltd.'. This company uses the prefix 'ZK' for a range of electronic products. There are various versions of this module in circulation, under all sorts of fanciful names. We purchased and tested a unit which was labelled 'WUZHI' as the manufacturer.
In any case, it is a very popular module, available from virtually every mail-order supplier of electronic gadgets. You can buy the module on AliExpress for € 10.39, and on Amazon for € 11.36. Banggood also has a slightly different version on offer for € 14.13.
What's included
For some reason, the ZK-DP3D is not supplied fully assembled, but in three parts: the circuit board, the front panel and the rear panel. You can assemble the unit using the standoffs, bolts and small screwdriver supplied.
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| The ZK-DP3D as supplied. (© 2026 Jos Verstraten) |
The user manual
We can be brief on this point. Not a single scrap of paper is included! So, in this article, we'll explain how to operate the ZK-DP3D.
The display
The monochrome LCD display measures 30 mm by 15 mm. Luckily, it shows only two sets of numerical data, displayed in large, highly legible digits. You can choose which data to display by clicking the 'SER/M' switch to the '+' or '-' position.
Data in the upper part of the display (click '+'):
- Input voltage (V).
- Output voltage (V).
- Internal temperature of the module (°C).
Data in the lower part of the display (click '-'):
- Current supplied (A).
- Power supplied (W).
- Amount of electrical charge supplied (Ah).
- Operating time (hours and minutes).
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| The data on the display. (© 2026 Jos Verstraten) |
The specifications
According to the manufacturer, the specifications of the ZK-DP3D are:
- Input voltage: 4.0 Vdc ~ 30.0 Vdc
- Output voltage: 1.00 Vdc ~ 30.0 Vdc
- Constant current source: 0.1 A ~ 2.0 A
- Maximum output power: 15 W
- Output voltage resolution: 0.01 V
- Voltage display accuracy: ±[0.5 % + 3 digits]
- Output current resolution: 0.001 A
- Current display accuracy: ±[0.5 % + 3 digits]
- Input: USB-C, USB-A, Micro-USB
- Output: USB-A, spring-loaded terminal block
- Protection: overcurrent, overtemperature, reverse polarity protection
- Standby power consumption: 18 mA
- QuickCharge compatibility: QC2.0, QC3.0, AFC9, FCP9, SCP5, AUTO, OFF
The safety features
- Over-power protection 'OP':
If the power output exceeds 15 W, the output switches off automatically and 'OP' is displayed. Pressing the 'ON/OFF' button switches the power supply back on. - Over-temperature protection 'OT':
If the internal temperature of the ZK-DP3D exceeds 110 °C, the over-temperature protection is activated and the output voltage is switched off. - Reverse current protection:
You can connect the unit directly to a battery being charged; no additional series diode is required to prevent reverse current flow from the battery to the ZK-DP3D.
The electronics of the ZK-DP3D
The circuit board
The photo below shows both sides of the densely populated circuit board.
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| Both sides of the circuit board. (© 2026 Jos Verstraten) |
The ICs
The part numbers of the ICs have not been laser-etched, so we can get some idea of the electronics within this small device.
- MS51FB9AF:
The MS51FB9AF is an 8 bit microcontroller from the MS51 series manufactured by the Taiwanese company 'Nuvoton Technology Corporation'. The chip is based on a 1T-8051 core, meaning that most 8051 instructions are executed in a single clock cycle. It features an eight-channel 12 bit ADC and 6 channels providing a pulse-width-modulated output. This IC is the central controller of the ZK-DP3D. It measures voltage and current via the ADC, drives the display, reads the encoder, generates the PWM for the buck converter and manages the protection circuits. - FP5139:
This is an asynchronous boost converter controller from the Taiwanese manufacturer 'Feeling Technology'. The chip drives an external MOSFET and is widely used in low-cost Chinese buck-boost modules such as this ZK-DP3D. - RU7570L:
An N-channel POWERMOSFET from the Chinese manufacturer 'Ruichips Semiconductor', specially designed for switching power supplies, DC/DC converters and power control circuits. In this circuit, it is driven by the FP5139 and, together with an inductor, a Schottky diode and output capacitors, forms the boost converter that generates the output voltage. - GN1621CB:
This is an LCD driver/controller for seven-segment LCDs. It is functionally very similar to the well-known Holtek HT1621B and is often used in low-cost circuits. - 2 x GN358A:
The GN358A is a dual operational amplifier that is compatible with the widely known LM358A.
Using the ZK-DP3D
The 'ON/OFF' push-button
Pressing this button briefly switches the output voltage on or off. This also applies to the voltage at the female USB-A connector on the output.
By pressing and holding this button for more than two seconds, you can choose whether or not the ZK-DP3D immediately applies the voltage to the output when you connect the device to the input voltage.
The 'SET/M' switch
- Click left or right:
As already described, this allows you to select what you want to see in the two numerical readouts on the display. - Press briefly:
This takes you into the mode where you can set the output voltage and the maximum current to be supplied. The 'V' or 'A' symbol will start flashing. You can then set the numerical value for voltage and current by clicking left or right again. By holding the switch in the left or right position, you can quickly decrease or increase the value. After approximately eight seconds of inactivity, the display will return to the standard view. - Long press:
This activates the mode in which the ZK-DP3D detects which fast-charging protocol the USB power supply at the input is using. By clicking left or right again, you can select the five supported protocols one by one. This is shown on the bottom line of the display. In 'AUTO' mode, the device automatically detects the charger's protocol.
The three LEDs
- Green 'ON' LED:
This lights up when the output voltage is available. - Red 'CC' LED:
This lights up when the maximum current is exceeded and the device switches to constant current mode. - Blue 'FC' LED:
This flashes whilst the ZK-DP3D is searching for the fast-charging protocol of the connected USB charger. It remains lit continuously once communication with the USB charger has been established.
Supported fast-charging protocols
- QC 2.0:
Stands for 'Quick Charge 2.0', a fast-charging technology developed by Qualcomm. QC 2.0 can dynamically increase the voltage supplied to transfer power more quickly. The voltage levels are 5 V, 9 V, 12 V and sometimes even 20 V. - QC3.0:
QC 3.0 stands for 'Quick Charge 3.0', the successor to QC 2.0, also developed by Qualcomm. The main difference lies in the much finer control of the charging voltage using 'INOV' (Intelligent Negotiation for Optimum Voltage). Instead of fixed voltage steps, QC 3.0 can adjust the charging voltage in small increments of 200 mV. - AFC9:
AFC stands for 'Adaptive Fast Charging', a fast-charging protocol developed by Samsung. It is widely used in Samsung chargers and compatible Chinese power adapters. At the request of the connected device, such a charger can increase its output voltage from 5 V to 9 V. - FCP9:
FCP stands for 'Fast Charging Protocol' and was developed by Huawei. With this protocol too, the charger will, at the request of the load, increase its voltage to 9 V and sometimes even to 12 V. - SCP5:
SCP stands for 'SuperCharge Protocol', it is Huawei's proprietary fast-charging protocol and is the successor to FCP. The main difference between FCP and SCP is that with SCP, not only is the voltage increased, but the maximum current may also be increased. This allows a high amount of power to be transferred without the voltage becoming extremely high.
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| The display for various fast-charging protocols. (© 2026 Jos Verstraten) |
Testing the ZK-DP3D from WUZHI
Introduction
We do not have any smart fast chargers in house, so we are testing our unit using various standard USB chargers, the USB output on our laboratory power supply and a powerful 5 Vdc power bank with a capacity of 20 Ah as the input source. This power bank is certainly capable of delivering the input currents required by the ZK-DP3D. The tables below have been created using this power bank as the input source.
The accuracy of the voltage indication
We connect our Fluke 8842A multimeter to the open-circuit output of the ZK-DP3D and set the module's output voltage to various values. As shown in the table below, the accuracy of the voltage indication on the display is excellent.
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| The accuracy of the voltage indication. (© 2026 Jos Verstraten) |
The accuracy of the current indication
We also connect our ET3255 multimeter, configured to measure currents, to the module's output and set the maximum current output to various values. As the table below shows, the current reading, particularly at low currents, is much less accurate than the voltage reading. We are unable to extract the promised 2.0 A from the device; read on.
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The accuracy of the current indication. (© 2026 Jos Verstraten) |
Output stability at 5.00 V
We set the maximum current to 2.000 A and the voltage to 5.00 V. We load the ZK-DP3D with our EL15 current sink and draw various currents from the unit. We measure the DC output voltage using the Fluke 8842A and the ripple voltage at the output using the Philips PM2454B mV meter. The measurement results are summarised in the table below.
What is striking is that the unit cannot supply a load current of 2.0 A. At just over 1.7 A, the ZK-DP3D starts to behave erratically. 'OFF' appears briefly on the display, after which the entire unit shuts down. A short while later, the electronics attempt to supply power again, but this also fails. This cycle repeats itself, and the only way to reset the system is to slightly reduce the load current and disconnect the ZK-DP3D from the power bank. We also have carried out this test with traditional USB chargers and consistently obtain identical results.
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| Output stability at 5.00 V. (© 2026 Jos Verstraten) |
The internal resistance of the ZK-DP3D
The output voltage drops by 9.9 mV as the load current rises from 0 A to 1.7 A. From these data, the static internal resistance can be calculated as 5.82 mΩ.
Output stability at 12.00 V
We repeat these measurements at an output voltage of 12.0 V. As expected, the ZK-DP3D is still unable to supply 2.0 A. The power supply now switches off at a current exceeding 840 mA. Between no load and a current of 800 mA, the voltage drop is only 4.7 mV, which gives an internal resistance of 5.87 mΩ. The ripple voltage remains virtually the same as that measured at 5.0 V.
Output stability at 20.00 V
The ZK-DP3D already shuts down at 520 mA. The voltage now drops by 16.0 mV between no load and a load current of 500 mA. The internal resistance is therefore 32 mΩ.
Output stability at 30.00 V
Same story: instability begins at just over 240 mA. Between no load and 200 mA, the voltage drops by only 4 mV, which corresponds to 20 mΩ for Ri.
The ripple voltage at the output
As already mentioned, the value of the output voltage does not make much difference to the level of ripple present. What pleasantly surprised us is that there are very few large peaks in the output voltage. The oscillogram below shows the ripple voltage at 12.0 V and an 800 mA load.
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| The ripple voltage at 12.00 V and 800 mA. (© 2026 Jos Verstraten) |
The dynamic behaviour of the ZK-DP3D
An important factor in the quality of a power supply is the behaviour of the output voltage under dynamic conditions. This can be tested, for example, by suddenly applying a current load to the power supply and observing how the output voltage responds. We carry out this experiment at 12.0 V with a current that suddenly rises from 100 mA to 500 mA.
The oscillogram below shows that the ZK-DP3D performs very poorly. When the additional 400 mA current is suddenly switched on, the output voltage exhibits a narrow positive peak of no less than 5 V! When reducing the current from 500 mA to 100 mA, there is a negative peak of approximately 4 V on the output voltage. The second small positive peak is associated with the switch from 100 mA to 500 mA. We cannot explain this second small positive peak, which occurs one second after the load current is increased.
These are, of course, completely unacceptable phenomena. It appears that the control system is very poorly designed and regulates far too aggressively.
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The dynamic behaviour of the ZK-DP3D. (© 2026 Jos Verstraten) |
Switching the output voltage on and off
When switching the output voltage of a power supply on or off, this voltage must rise and fall smoothly, without any unusual spikes or other transient phenomena. The oscillogram below shows how this works with the ZK-DP3D. The power supply is set to 12.0 V and the current sink is set to 500 mA. When the 'ON/OFF' button is pressed, the output voltage rises from 0 V to 12.0 V in ten equal steps in just under one and a half seconds. When the switch is operated again, the voltage drops off smoothly, without any undesirable transient phenomena.
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| Switching the output voltage on and off. (© 2026 Jos Verstraten) |
Our opinion on the WUZHI ZK-DP3D
Is this a poorly designed product? Yes, we can wholeheartedly confirm that. The maximum current of 2 A is never achieved. Perhaps the results would improve if you powered the ZK-DP3D using a smart charger that supports one of the fast-charging protocols and provides a higher voltage. However, the description on the sales pages does not state that the 2 A current is only guaranteed with this type of charger; it should also be the case with an 'old-fashioned' standard charger.
Quite apart from this, the way the device responds to a sudden increase in load current is the final nail in the coffin for the ZK-DP3D. Not all circuits requiring a 12 V power supply can cope with a sudden surge in voltage to 17.0 V!
ZK-DP3D, USB to 30 V converter
