I can't remember why I have a bunch of these, but I just found them and I need help figuring out what components I need.
If I wanted to put together a buck converter that just steps down a 12VDC 2A wall wart to 5VDC, what parts do I need, and what part determines current limits?
I also have a bunch of Rayovac LA6V rechargeable 6V 5Ah SLA lantern batteries. If I wanted to get 5V from these, can I use the MC34063? If so, what else do I need?
Hoping someone more adept at reading datasheets than I strolls along to help
For example, I don't even know what component I would use as an inductor (Buck circuit on p.6). Do they sell particular inductors rated somehow?
http://www.nomad.ee/micros/mc34063a/
This is a simple design tool which calculates all the values for you for any of the 3 modes of operation.
The only slightly tricky part is to get the Inductor right, ie correct grade of ferrite for the switching frequency, and the correct size in terms of maximum current.
allanhurst:
The MC34063 is an INVERTING buck/boost convertor - with 1.5A switch capability...
If that's OK it might do.
Allan
No it's not. It's buck OR boost OR inverting, depending on how you wire the external components up. I'm sure it could be a buck/boost of some kind too if you wired it up properly.
It depends on your goals. If you want to learn about switching regulator design then you are on the right track. However if your goal is to convert the wall wart / batteries to 5V I would suggest looking on eBay for a small board that is already built.
For the 2A you want a real switching regulator. Reason; as switching regulator is much more efficient and will not create loads of heat while dropping the 7V or so.
For the batteries, if your load is low (< 0.1 amps, kind of arbitrary but is in the ballpark) you can get a linear regulator AMS1117 based in either 5V out or 3.3vout. Reason: this type of regulator will operate when the input voltage is very close to the output voltage which will happen when the batteries discharge.
I've got AM1117's, small buck chips, etc. But I've got these MC34063 ICs and the marketing material makes them sound real useful, and I want to figure out how to make one while learning about how it works.
INTP:
But I've got these MC34063 ICs and the marketing material makes them sound real useful, and I want to figure out how to make one while learning about how it works.
Max switching frequency of 100kHz. Seems like an older generation DC/DC chip.
Modern converter chips now go to 2Mhz (smaller inductors).
Leo..
