Buck regulator design, which parts can be slightly different?

[kostoglotov]

I want to build http://www.hobby-hour.com/electronics/lm2576hv-adj-buck-regulator-schematic.png

From http://www.hobby-hour.com/electronics/lm2576-step-down-switching-regulator.php

I might not be able to source exactly the same parts. I assume I have to use the same IC, but could I use a, say, 200uH inductor instead of a 100uH? Or slightly different types of capacitors, with different capacitances? How about that Zener diode?

If I'm stepping down 24 to 3V and drawing up to 400mA, I'll probably still want to attach a heatsink, no?

edit: the output voltage will be running a small 3V gear-motor system needing to lift a small amount of weight (half to a couple of kilos) vertically in a reasonable amount of time.

 

[Integrand]

Yes the choice of external components is flexible, but your first port of call for such a question should always be the datasheet: http://www.ti.com/lit/ds/symlink/lm2576.pdf Your questions are answered there. Perhaps you might ask follow-up questions here if anything remains unclear?

 

[davenn]

How about that Zener diode?

it's not a zener diode
It's a high switching speed Schottky diode

as for the inductor ... read the section of the datasheet labelled "Inductor Selection"Dave

 

[the_emi_guy]

If your goal is to learn a little about how we design switching regulators these days, you may want to pick a different part. Linear Technologies and TI both have a wide variety of regulator ICs that have really cool simulation tools available (LTSpice for Linear Tech, Webench for TI). They allow you to tinker with the component values and observe the behavior in simulation.

Unfortunately, the LM2576 for some reason is not supported by Webench.