This is a succinct account of my experience with the cheap electronic power supply module from China, “DC-DC Module 5-A/7-W (ERPC0575DC) XL4015.” I have used quite a few over the years and have to say that these types of modules are great for hobbyists and makers. Here is the module I have tried, but don’t take this information for granted. There are countless suppliers and very high variance with most modules, not to mention some room for user misplay!
I chose this module because it had an output rating of up to 5 A, more than the cheaper versions that we see online. It also included an on-board digital voltmeter with an option to show either input or output voltages. At first sight, I thought that this was a digitally controllable power supply with +/– buttons to adjust the output voltage as required. It was a misconception as it is, in fact, a 180-KHz fixed-frequency PWM buck (step-down) dc/dc module capable of driving a 5-A load with high efficiency, low ripple, and excellent line and load regulation. A multi-turn potentiometer is included for output voltage adjustment. The digital voltmeter simply displays the current input or output voltage (it can also be calibrated for accuracy).
The output voltage is adjustable from 1.25 to 35 V from an input of 4 to 38 V. Note that the input voltage must be at least 1.5 V higher than the required output voltage.
The module is available as a pre-populated board and requires zero soldering — it comes ready to go out of the box. Also, there’s an extra heatsink for the XL4015 chip included with it. Major components in the module are showed in the following figure:
In addition to this, there is a small microcontroller in the digital voltmeter circuit (my teardown article will be published in the near future). It’s most likely an 8-bit MCU from STMicroelectronics or Holtek.
Remember, if you are facing difficulties in the calibration process for the first time, just turn the preset pot counterclockwise for 10 rotations as the default output voltage (factory preset) is around 20 V. Also attach the heatsink that comes with the module if you are a power user!
This is absolutely a good device, but without access to a plentiful supply of these modules, it is hard to say if there are any unseen anomalies in the design itself or if the modules contain bad parts. Anyway, I prefer a multi-turn potentiometer (with a long shaft) in lieu of the nasty preset pot for the sake of user convenience.