Switch mode power supply Pic Micro

[iw2fvo]

Hi to All,
I am searching for a sample PicBasic program in order for me to build up a power supply using the switch mode solution.
The input voltage can change from 10 VDC to 22 VDC max.
The current required at the output is about 500 mA @ 6.8 VDC
Thanks
Ambrogio
IW2FVO

[Phil Moore]

Ambrogio,

Use a switch mode regulator. I've had great success with the LM2576.

http://www.national.com/mpf/LM/LM2576.html

You'll need 2 x low ESR caps, 1 x 47uH..100uH choke and a fast recovery diode. You can even build your supply on Veroboard if you need to.

Way less painful than trying to use a PIC.

Phil.

[iw2fvo]

Hi,
thanks for the suggestion.
I have to use this smps to load a lead acid battery, 6Vdc nominal, 3 A/h from a solar panel ( PV ) . The panel has a rated power of about 3Watt.
The best way would be the use of a MPPT controller to adapt the variable characteristics of the panel to the battery for having the best transfer of power to the battery load.
Do you think that controllling the feed_back of your suggested National Controller i will be capable of controlling the panel MPPT ?
Thanks for any reply on the matter.
regards,
Ambrogio

[Phil Moore]

OK,

So what you really want is a SLA battery charge circuit driven from a solar panel. Why didn't you say so? :)

Now, I'm no battery expert, but from what I understand, (sealed) lead acid batteries are happiest either with constant current charging or trickle charging.

Most voltage regulators are just that - voltage regulators, not current regulators. I'd suggest you check out specialist battery charge circuits from manufacturers like Maxim or maybe Analog Devices.

Also, you mentioned your battery was a 6V battery - that's a little uncommon where I come from (Australia) for SLAs. Over here we have a retailer (Jaycar - www.jaycar.com.au) who have a range of PV regulators for 12V SLA batteries which is what is more commonly used (along with 24V).

Regards
Phil.