Simple Digital Power Supply

[Free_Will]

opa549 .regulator project

Hi,

I need to design a simple 0-5V digital power supply to ease my life in the lab.Producing 0-5V with a DAC is baby toy for all.

What I need is a power efficient block that can increase my output current. My current microcontroller supplies 40mA for 0-5V range and I need to source few hundred miliamps.

Any suggestions will be appreciated.

Stay cool.

 

[cesariv]

If you already have 0-5V @40mA, you only need an amplifier to boost the output current. a new easy way could be using a power operational amplifier such as opa549.

To implemet regulation, you need an ADC to feedback the actual output to the microcontroller.

 

[DarkJedi]

Get a transformer, from 220/30Vac (Could be to 10Vac too, the idea is to have over 5V, at least 5 volts more), use a diode bridge to rectify the wave, 3000 uF cap to take care of the spikes, at this point you have a dc level voltage, you can use a 78xx to rectify the voltaga to the one you want, in this case 7805 would give you the 5V you want.

The transformer should had 3 output, the middle one is groud.

This simple power suupply would give you like 1 Amps, depending on the rectifier (78xx) you use, trexas instruments got ones of 1.5 Amps and there are circuits on their datasheet to get even more current out of them, use a power disipator for this device.

hope it helps.

 

[goodboy_pl]

cesariv method is a stright forward method though it requires +/- input voltage (does not work with single supply input).
the problem is simply solved with taped transformer and two half wave rectifier (can be replced with one full bridge diode rectifier with one input grounded!)

BEST!

 

[samcheetah]

if u need a separate 5V supply then the solution suggested by DarkJedi seems to be perfect.

but i dont get it when u mention about your micro giving 0-5V @ 40mA. do u want to control the supply voltage with the microcontroller. well then thats a separate scenario. but if u just want a variable 0-5V mains powered supply then the LM317 is a good choice.

i remember a digital power supply project in EPE. i think it was in Jan 2001 or something like that.

 

[Free_Will]

Hi All,

Digital Power supply will be adjustable in milivolts range. I do not have problem with this. I just need current boost and I do not want to use transformer also. Power Opamp seems a good way for this , is there any way to use just few transistors to source 200-300mAs? Current Boost transistor circuit works , any schematic?

P.S : I will use ADC as well to measure the output voltage and show it on BCD or LCD. This will be a PSoC project.

I would like to share this project on my web page as soon as I make it.
(electronicsclub.cjb.net)

 

[leo_o2]

Switching converter from Maxim-ic.com?

 

[dsaf13]

Hi,

Well, I think that LM317 wouldn't do well below 1.23V. At least not without an additional negative voltage source.

A relatively simple solution is to use a opamp configured as a voltage follower or non-inverting amplifier, with npn bipolar transistor(s) in it's feedback loop.

But than you'll have to provide some additional voltage for the opamp and transistor, to compensate for the voltage losses on BE junctions.
That wouldn't be a problem if your micro is powered from a standard voltage regulator (say 7805)*. Voltage on it's input should be at least 2V higher than on output, so you can draw power for your opamp booster from there, and that should cover for all the voltage losses.
(*presumption: 5V supply for psoc)

Check LM324's datasheet at www.nsc.com for a general idea (Power Amplifier, page 9). You might use 324, or replace it with amp swinging from rail to rail.

Beware of the excessive dissipation...

Or use a switcher

 

[Free_Will]

dasf13,

That's the exact method and advices that I was looking for.


Welcome to EdaBoard!

Thanks,
Free_Will