Thanks Rich.
?
For the load, is it a motor or something like that? Just trying to get my head round why the startup current is 10x the run current.?
?
Some feedback on the PSU, not trying to pick it apart, just some thoughts:
?
- There's quite a bit of resistance in the chain. Adding it up in my head it's over 3 ohms. A 3 amp draw will cause a minimum of 9 volts drop, and the resistance in the earlier part will cause much more. The chart bears this out - there's a drop of 12 or 13 volts between the low current and the high current draw
- As you are feeding into a regulator, some ripple is OK on the output of your PSU. The solid state regulator from your datasheet has a line regulation of 0.015%. That means it will cut the ripple going in by 6000-7000 times. So some ripple is OK as long as the "trough" of the cycle doesn't drop below the dropout value of the regulator
- The RC sections will give a small amount of ripple reduction but will mess up the regulation. Again, think about how much ripple is OK and drop the RC sections. And probably the LC too
- If I was having a go at this, I would probably just have transformer, bridge, capacitor. And that's it. Nice and easy, compact and should give better regulation
- The 16.5V seems high for a 5V regulator, would need to keep an eye on power dissipation as it's a linear regulator
?
Putting all the above into practice, I've clipped an example where I've used a 9V / 3A (10% regulation) transformer into a simple capacitor. On the high current draw there is about 3V peak to peak of ripple. That may look bad, but the regulator will get it down to 0.0005V which may or may not be OK for your application. The light load rises to 12V which means your regulator will drop 7V @ 0.25A which is 1.75W, but worse is the 3A draw where it will lose 12-15W. I skimmed the data sheet for a power envelope but couldn't quickly find anything, just some stuff about how it limits the power by shutting down automatically.
?
Hope this is some help to you.
?
?
Regards,
Duncan
?
?
