I'm very new to electronics, this is the most complicated circuit I've tried to create thus far. I'm attempting to step down a 24V DC input to 5V output. I'm skipping the output filter for right now just until I get the buck to work. I know that in a real circuit I'll want the traces to be shorter and the components as close together as possible.
I'm having 2 problems.
- The output (red trace from C33) is about 3.5V
- I'm unclear if I should have the common ground across the breadboard.
- Buck Converter
- 470uF Cap
- R1 1.2kO Resistor
- R2 3.83kO Resistor
- R3 0.33O Resistor
- C1 100uF Cap
- 470pF Cap
- 220uH Fixed Inductor
Here's another picture with labels.
Here's the schematic from the datasheet. It's almost exactly what I'm trying to do.
Edit 1 Taking the suggestions of both letsfetz and Yoshimitsu I've made some changes.
- I'm now using this inductor
- I've moved the diode and rerouted the line coming from pin 2 (see image)
I'm still unclear on if I should connect both ground rails. If I do connect both grounds then I read about 23V on the output. If I do not I read about 4.5 V on the output (for both reading I leave the ground of my multimeter on the J side ground rail).
Edit 2 I'm still trying to figure out why I'm getting about 23V on the output. Below is a screenshot from my oscilloscope. 5v/div & 1ms/div. Reading output of pin 2 with respect to ground rail. I have a load of a LED with a 1K0 pull up resistor. The voltage measured after the LED is about 2.8V
Edit 3 I never figured out why it wasn't working on the breadboard. I created a schematic and board design file in Eagle, sent it to a PCB mill and after soldering all the same components, it works. The only differences are that I added the output filter and a couple LEDs. Wish I knew why the breadboard didn't work.