Schematic Capture

A project log for OpAmp Buck Regulator

A quad OpAmp Makes a Buck Regulator

aaron-lagerAaron Lager 04/23/2023 at 16:300 Comments

Satisfied with the simulations performance, it's time to start making it for real.

Step one, schematic capture.  I use KiCAD 6, and found that there was an update to version 7 during the middle of drawing.  I was getting frustrated with how KiCAD deals with wires when dragging components around.  During my search for a solution, I found that version 7 is the solution.  Normally I don't update software in the middle of a project, but I took a calculated risk, and the transition was seamless. Score!

I made three minor changes (as compared to the LTSpice schematic) as I was drafting the schematic.

  1. The 1.25V reference was changed.  The LT1389 is a 0.05% accurate part, and costs about $8 USD.  So I changed it to a MAX6101, 0.4% accurate and only $1.48 USD.
  2. The output capacitance.  Instead of a single component, I made room for three.  This will give more flexibility during testing.
  3. I also added a bypass capacitor for the opamp package and input connection.