Adjustable DC/DC Buck converter

With many projects, especially ones that use battery for power or mixed voltages, there is a need to have some sort of DC/DC converter. While there are many off-the-shelf parts, there are less those that would be simple to integrate part of custom electronics or ones that provide enough current for Raspberry Pi for instance.

With that in mind I decided to make a small form factor custom PCB that used Semtech TS30013 chip that is available up to 3A current and in adjustable and fixed voltage versions. Semtech product specification. It takes wide input voltage range (4.5 to 18V for 3A version) which is sufficient for normal 3S or 4S lithium battery types. Adjustable range is also wide from 1.5 to VCC-1V range.

Buck converter has the advantage of having quite good efficiency compared to LDO. That is especially important with battery powered devices like the camera dolly. 5V buck converters are easy to come by even ones with reasonably high output but if you need something other than 5V or 3.3V those are bit more difficult to find. Like the 7-8V power for DSLR. Adjustable version of TS30013 is perfect for that purpose.

Schema of TS30013 based buck DC converter

Datasheet of the TS30013 practically gives you ready layout and schema for the circuit. Only thing left to be decided is the voltage divider values that give correct voltage (R11 and R12 in above schema)

Voltage output can be calculated simply form formula Vout = 0.9 * (1+R11/R12) . So in above example it should give 7.92V output.

Layout of the adjustable buck DC converter

Layout I came up with is 20x15mm area small PCB with input and output with 0.1″ standard pin header and separate enable pin that can be used to turn converter on and off. It turns on by default if EN pin is left floating. Resistors and capacitors are with 0603 size components though 0805 size fits to the pads without problems.

Assembled buck DC converter

Components are small enough on the PCB but assembly isn’t too difficult. You need obviously stencil to apply solder paste and oven to solder the components but if you have those it is not too bad and result is very satisfactory.

IR image of the device under 1.5A load (9V version)

Small area of the device of course means that there isn’t much area to dump the heat to. back side of the PCB is all ground plane in order to dissipate the heat. Only component running hot is the TS30013 chip which is obviously expected. Going 3A (or 27W) with this 9V device is possible for short while but output starts cutting due to thermal protection.

I made a short video of the assembly of this device which I will link here once it is ready. I have few of these extra so if you need one it can be ordered through the web shop here. I can obviously make more of these since I have stencil ready if there is any more demand for these.