1/31/2026 - Deciding on parts and specs

Okay, so i want to create a buck converter because i have to do some electrolysis. Electrolysis usually requires low voltages and high currents, thus i need a buck converter.

I have thought of using the following parts:

1. AON7272e MOSFETs
2. TPS40305 Buck Controller IC

The Specifications I am aiming for are:
8V - 20V Input Voltage
2V Typical Output Voltage
25A maximum current

I will be making the Design as Efficient as possible from my side


this is what the simplest buck converter looks like!

2/1/2026 10 AM - Change of plans

Okay, i have got the buck IC, but then i realised that the stuff i am getting may be underkill(it would cause heating issues), so, i changed my inductor to PA2607.301NLT, it has 290uOhm resistance, 300nH inductance, and i am thinking of using the NTMFS5C628NLT1G as it provides an Rds on resistance of only 2.9mOhm.

I have also worked a little bit on the schematic, but most of time is spent on finding right parts and their availibility in india, as i have to get it done fast, i'll be ordering from indian suppliers.

calculating values for components is kinda time taking and tedious, i have not yet calculated all the values

2/1/2026 12 PM - Controller Part Done

This controller part is done, now i focus only on the power stage, and now that i think about it, i feel like adding shunt resistors, they can be really important in measuing current, probably like 1mOhm shunts, because those will have very low power loss.

The power loss per shunt at 1mOhm per shunt will be 0.625W, and there will be a total of two of them, one at output and one at input. so total of 1.25W power loss max

2/2/2026 - Schematic Complete!!(almost)

I worked on the schematic, the work is almost done, i just have to make the new inductor footprint and store it, change the MOSFET footprint, and then i just have to start with the PCB. In this session, i made a few minor changes to the controller circuit, and the big decision i made is to remove the 100uF and the 47uF caps, and rather order ceramic caps, because they are generally better than these, thus i removed 147uF on the output and added 220uF on the output, and removed 47uF on the input and added 66uF on the input

Looks yum

The schematic is done, i have decided to use XT60 connectors for connecting the input and output, and to use a LiPo battery. There are 4 other holes for mounting and 2 for holding XT60 connector wires so that they dont ripp off the pads as the pads are fragile while the wires are thick.

found this in the datasheet and thought i had to share, apparently noise can get from GND to other sensitive components like the FB system, thus it is important to keep these two connected via thin traces.

Here's the full schematic:

2/3/2026 3 PM - Changed footprint of the MOSFETs + change of plans AGAIN

Well well well, it is me again with another change of plans, I was originally gonna order from lion circuits to get my parts early, turns out they are really really expensive parts wise, so i am going to be using LCSC(goated fr). The cart on LCSC is $10 cheaper for same components, but ofcourse i will find better components in LCSC and try to make it even less.

Oh and i changed the MOSFET footprint, turns out i was using the old footprint, which is not the size of this mosfet.

PC: the Mouser site is goated for great footprints, and the footprints are much better than the EasyEDA footprints!!

Starting the PCB now, wish me luck :sob:

2/3/2026 4 PM - Reality

I gave realised that the Buck i am making might just be too much for a 1oz PCB based board, but the 2oz PCB will be too expensive, so i have to go with 1 oz, and i am using an online IPC-2152 current calculator, which tells me that i need a minimum of 20mm to carry 25A and not have temp rise above 39 C

The calculator i am using is this:

I have decided that the bottom plane will be an uninterrupted ground plane, and the top layer will have multiple different pours, thus carrying high current, something like this: