I am a Road Tester of the TI-PMLK Buck Experiment Board: TPS54160 & LM3475.
It's an educational kit - board and book - to learn buck converter theory and practice.
Because it's an educational kit, I give minus points each time there's vendor lock-in .
I applied for the Road Test to check the educational value of the kit. The focus in this blog series will be on the Lab Manual and exercises.
In this blog, I measure the efficiency for Exercise 1.
Doing the measurements
This is where the educational value of the kit is really excellent. The book doesn't discuss Buck regulator theory or measurement principles.
It assumes you have those skills. I think that's a good starting position in this case.
If you don't understand Buck converters or lack the skill of using multimeters and oscilloscopes, it doesn't really make sense to do these experiments.
They build upon your knowledge. They are not the base for it.
|Goal of Experiment 1:|
The goal of this experiment is to investigate how the efficiency of a buck regulator depends on the line and load conditions and on the switching frequency.
The document reviews the parameters that play a role in efficiency, shows the components that have a loss independent of load and components that have load dependent losses.
The exercise is to measure input and output power with varying load, for an input voltage of 6 and 24 volt and calculate efficiency.
Then you have to compare that with the efficiency calculation. You get enough help in the doc to get that calculated.
Simulation affectionados (yes you Jon) may want to run it through Spice or the likes.
Then follow the steps to set everything up and perform the exercise (click to enlarge).
You record both calculated and measured values in a table, for those efficiency and loss tests.
Here's a few of my measurement recordings and some scope captures:
- Input 6 Output current 0.8 A
- Input 24V Output current 0.8 A
Here's what the manual shows for 24V 1A. It's obvious that my current measurement method (blue in the capure above vs. green in the TI manual) is not up to the game.
What I haven't done yet is to measure the behaviour when the regulator operates in non-continuous mode.
That's a todo for the next article. I'll also comment on educational value and vendor lock-in score of the kit (spoiler: high and low )
|1a: 1st Experiment Set-up|
|1b: 1st Experiment Lab Setup|
|1c: 1st Experiment Measure|