Hello world, earlier in September I ran into a problem with a switching regulator.
In electronics, a switching regulator is one of the most basic building blocks. You’d think it’s straightforward. But somehow, I just couldn’t make it work.
For the record, I was using a TPS54334, and while it produced a nice, stable output voltage with no load, the moment I connected even a moderate load, the voltage dropped like a stone in water.
I spent two weeks troubleshooting the issue. I tried adding capacitors, probing the output, watching the chaotic switching waveform across the inductor, even adding a snubber across the Schottky diode, nothing helped.
At first glance, my schematic looked fine. Everything seemed in order. But after exhausting every “minor tweak” I could think of, I finally decided to revisit the datasheet.
And there it was, my mistake, staring me right in the face.
The ENABLE pin.
I had tied the enable pin to VIN with a pull-up resistor, but somehow, the pull-down resistor was also connected to VIN instead of ground. So the regulator never truly had a defined “low” state, it was basically floating when it shouldn’t be.
It’s one of those moments where you just sit there and think, “How did I miss this?”
Lesson Learned
When something refuses to work, it’s rarely the tiny tweaks that fix it. Adding capacitors, snubbers, or chasing noise on the scope might help if your fundamentals are solid, but if you’ve made a basic wiring mistake, no amount of patching will save it.
Sometimes, the most productive troubleshooting step is to take a deep breath, step back, and read the datasheet again.
Anyway, issue solved. On to the next mystery.