XL4005 Buck Converter

Input 5-32V, Output 0.8-30V, Current 5A, CV, CC

The XL4005 from XLSEMI is a popular step-down converter capable of outputting significant currents of up to 5A.

The chip is sold separately and also embedded in a complete breakout, board ready-to-go, for EUR 2-4:

Although the actual controller XL4005 is possibly a bit outdated but technically fine, the breakout boards embedding it may be fraudulent.

For example, the depicted breakout board comes with 3 (three) potentiometers (and no documentation). Simple boards have one potentiometer (for constant voltage), more advanced boards have two (constant voltage and constant current), but there is no need for a third potentiometer.

It turns out the third potentiometer controls the threshold for an on-board LED that lights green for low currents and red for high currents - a quite eerie and specific feature.

While such a LED might be fun for some and can safely be ignored by others, the board has more serious flaws: the maximum output current is capped at around 1A, so while the XL4005 used on the board can handle up to 5A, the board cannot. If all you require is 1A, then there are much cheaper and so much smaller converter boards available.

On top, many cheap breakout boards use counterfeit controllers that may still work for you but have significantly different specs. For example, some counterfeit XL4005 do not run at 300kHz switching frequency but rather 50kHz.

If the core of the inductor on the board is colored yellow-white (like the depicted one), then it might be a cheap iron core with a maximum frequency of around 70kHz (real XL4005 run at 300kHz) that is originally designed to be used in filters, not in DC-DC converters.

Takeaway: controller specs and data sheets are for the chip only. The actual board design determines what you get out of it. Since typically there are no schematics available for breakout boards, the only way to find out is to test and measure yourself with a dummy load and see if a given board is suiting your needs before you buy in larger quantity.

Property Value
Input Voltage 5-32V
Output Voltage 0.8-30V
Max Output Current 5A
Efficiency up to 96%
Switching Frequency 300kHz

The maximum output current of 5A requires to add a heat sink to the chip. While the XL4005 is dependable and rugged, avoid exploting its maximum specs. Boards using XL4005 run well for long-time output currents of 2-3A.

Stable output current also depends on the voltage difference between input and output. The lower the difference, the less work needs to be done, and the more stable output current and less heat is produced.

As mentioned, some boards cut off current at very low thresholds such as 1A. In these cases, you definitely need no heat sink but a different board.

Feature Supported
Constant Current yes
Output Shortcut Protection yes
Over Voltage Protection no
Thermal Protection yes

Data Sheet


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(content created Feb 27, 2024)