DC-DC Step-Down converters (also known as ‘Buck’ converters) convert a higher voltage to a lower voltage while also stepping up the available current.

This DC-DC Step-Down converter is adjustable and capable of outputting a voltage in the range of 1.25 to 36V at a continuous current of up to 5A and short-term current of up to 8A with a maximum power output of up to 120W.  The input voltage must be higher than the output voltage.

The XL4016 converter IC has over current limiting and thermal shutdown features built-in.

The board has 4 holes in the corners which can be used for mounting it permanently if desired using  small screws.  There are some components on the backside which need to be protected from shorting if mounting close to a metallic surface.

Output Display

The built-in green voltmeter display shows the output voltage.

The display has a stated accuracy of ± 0.1V.  There is a small potentiometer on the back of the module that can be used to calibrate the display against a reference voltmeter if desired.

Voltage Adjustment

The module has a multi-turn potentiometer for adjustment of the output voltage.

Turning the pot CW increases the output voltage while turning it  CCW decreases the output voltage.

The lowest output voltage is approximately 1.25V.  The upper limit of the adjustment range will depend on the input voltage and is typically about 1.5V less than the input voltage.  With a 12V input for instance, the upper output limit will be approximately 10.5V.

Input Power

These are compact boards with input power applied to one end and output power available on the other end, unfortunately with no clear markings unless you read Chinese.

With the LED display facing towards you, the input is on the left and the output is on the right.  The connections are made using screw terminals for easy connection to wires for hookup.

The minimum recommend input voltage is 5V.  With a 5V input, the LED display will dim, but the converter will continue to operate OK.  At 6V input, the display will be at full brightness.

The input has a reverse polarity protection diode.

Input Power Terminals (Left Side)

• ‘+’ = Input voltage (5 to 40V)
• ‘-‘ = Ground

Output Power

Output power is available on the right side of the module.  It also uses screw terminals for easy connection to wire for hookup.

Output Power Terminals (Right Side)

• ‘+’ = Output voltage (1.25 to 36V)
• ‘-‘ = Ground

OUR EVALUATION RESULTS:

This DC-DC Converter is built with some heavy duty parts which is nice to see.

Heat sinks are large and finned with good thermal coupling and they are also electrically isolated.  Because of the large heat sinks, force air cooling if utilized is very effective and can easily decrease temps by 30°C or more.

The inductor utilizes heavy-duty wire that can handle the rated current. The Schottky diode is a massive MBR20100C dual 10A unit which is also mounted to a large heat sink.

We have pushed 10A though the device with some fan cooling to test limits, however the chip is only rated up to 8A, so even with fan cooling, more than 8A should not be pulled from the module. For long-term use, 5A is a good upper limit depending on the input / output voltage settings and assuming no fan cooling. With fan cooling, 8A is supported in many of the modes.

The table below gives some thermal results with an ambient temp of approx 25°C and no fan cooling.  We tested at 5A and in some cases then tested at 8A or the upper current limit where we were getting close to a thermal shutdown.  With forced air cooling, the temperatures dropped by about 30°C on average when under higher loads.

Output Current vs Input / Output Voltage

The ripple on the output is typically around 100mv peak-peak which is pretty good.  The module does have a fair amount of noise spikes that average 150-400mV depending on loading but this shouldn’t be an issue for most applications.

The scope capture below shows the typical ripple/noise found on the output.

XH-M404 Ripple and Noise