Suggestions for a 5v voltage regulator?

[qa9b]

I'm working on making a solar-powered battery charger, and could use some advice.

To begin, I have a solar panel which I plan to use to trickle charge four rechargeable AAs connected in series. I assume this is possible. When fully charged, they should put out a little more than 6v.

I want to use these batteries to provide a steady 5v current (connected devices will draw a max of 500mA). However, it's clear that the AAs will drop below 5v well before their power is fully discharged. I can't seem to find plans for a voltage regulator that can boost the voltage as well as trim it. This is where I need the most help.

In addition, what could I use to automatically stop the charging when the batteries have reached 6v, as well as cut the discharging when the batteries have dropped below whatever the minimum requirement for the regulator is?

I know I'm a bit of a noob , but I'd really appreciate some advice/links to info on this topic...
qa9b

 

[dknguyen]

It's called a buck-boost regulator, or a flyback regulator, or a SEPIC converter. Unless you have the know-how (and space and time) to build one from scratch, it's easiest just to buy an IC and wire it up to the necessary inductors, resistors, and capacitors.

WHat type of AA batteries? NiCd? NiMH? It makes a difference. That may be why you should just fine a battery charging IC that should generate the proper voltage for you, as well as monitoring the cut off and everything like that.

I want to use these batteries to provide a steady 5v current (connected devices will draw a max of 500mA). qa9b

Huh? Do you mean a steady 5V voltage with a maximum amp draw of 500mA?

 

[Karbos]

Switching regulator 5VDC:
Dimension Engineering 5V 1A Switching Regulator | Let's Make Robots!

**broken link removed**

 

[qa9b]

Edit: posted below before I saw those replies. Man, that was quick! Let me read... =)

Just found this...
**broken link removed**

Would that do the trick? If I put the AAs in parallel, then it would never need to trim the voltage, right? Is there an alternate method to doing this (a non-IC way?).

Granted, the max output of that chip is 200mA, but I could live with that. What if I just put the outputs from two of them in parallel?

 

[qa9b]

It's called a buck-boost regulator, or a flyback regulator, or a SEPIC converter. Unless you have the know-how (and space and time) to build one from scratch, it's easiest just to buy an IC and wire it up to the necessary inductors, resistors, and capacitors.

WHat type of AA batteries? NiCd? NiMH? It makes a difference. That may be why you should just fine a battery charging IC that should generate the proper voltage for you, as well as monitoring the cut off and everything like that.



Huh? Do you mean a steady 5V voltage with a maximum amp draw of 500mA?

Haha, got me. Yes, 5V @ 500mA (max) is what I meant.

See my above post. Something along the lines of that? Granted, it doesn't trim ("buck"?) the voltage, but as I mentioned, is that completely necessary if the batts are connected in parallel?

If I just want to trickle charge, what type of batteries would I want? I assume that if I went with an IC, the IC would be specialized for a certain type of battery. As nice as ICs are, they involve a certain shipment period (i.e. forget radioshack) and I'd like to stick with the basics as much as possible. For the charging part, could I use a zener diode to turn on a light (to indicate full charge) when the batteries hit a certain voltage?

 

[qa9b]

Switching regulator 5VDC:
Dimension Engineering 5V 1A Switching Regulator | Let's Make Robots!

**broken link removed**

You may have been misguided by my not-so-specific thread title. I need to get 5v out of this even when my source is below 5v.