Buck and boost with any pic

[be80be]

I been play round with small delay and a small 220uH coil the coil rated at 500ma .

If you set a delay of like 6 to 10 uS you get a boost of almost 4 times Vdd

And you can very the delay to lower the boost here a little circuit to play with you can use the timer if you want.

I been using it for power for the LCD with 3.3 volt chips works fine

Here a link if you want to no more about the how to figure parts a detailed guide to building your own DC/DC converter using a little PIC, by Olin Lathrop

If you read the link it tells how to get maxim efficiency and how to figure all the parts needed

 

[MikeMl]

Burt, you have to very careful with this circuit. Unlike using a true SMPS controller IC, there is nothing in this circuit which limits the current through the inductor to the optimum level for the power transfer to the load, so the efficiency will be poor, and if you make the pulse width too wide, you can saturate the inductor, and/or blow up the transistor.

 

[be80be]

I have a 20 ohm 1.25 Watts resistor to limit power in that should keep it at a safe range.

But your right you can saturate the inductor by using to long a delay

If you read the link it tells how to get maxim efficiency and how to figure all the parts needed

MikeMl Thanks for added info

Here to show how this works

 

[RMMM]

Have you never read Mr. RB's inquiry into the same? Very good read.

PIC-SMPS, using a PIC as a SMPS

 

[be80be]

He using it to lower the voltage I'm boosting it from 3.3 volts up to what you need

But it's a nice read thanks RMMM

 

[AtomSoft]

nice... so i can use some small 6 pin pics to make a boost converter heh.... there cheap!

PIC10F200T-I/OT Microchip Technology Microcontrollers (MCU)

$0.50 each and $34 for 100 of them heh... nice to use with this...

 

[be80be]

I was thinking about using for EL back lighting It would be nice if the 10f200 had ADC

 

[AtomSoft]

what is the ADC used for in there? Feedback for what?

what app note is that.. im too lazy to search heh

found it :

https://www.electro-tech-online.com/custompdfs/2010/12/01146B.pdf

 

[AtomSoft]

More info on the feedback stuff here page 6:

https://www.electro-tech-online.com/custompdfs/2010/12/00258a.pdf

 

[AtomSoft]

Anyway for $0.08 more you can get the PIC10F220

PIC10F220T-I/OT Microchip Technology Microcontrollers (MCU)

Which has ADC and is small!

 

[be80be]

Feedback you could control voltage output Like this It just a example not working model

 

[Mosaic]

Anyway for $0.08 more you can get the PIC10F220

PIC10F220T-I/OT Microchip Technology Microcontrollers (MCU)

Which has ADC and is small!

MICROCHIP|PIC10F220T-I/OT|IC, 8BIT MCU, PIC10, 8MHZ, SOT | Newark.com

9c less....

 

[AtomSoft]

nice!!! heh... i havent shopped at newark in so long! ill have to check them out

 

[Mosaic]

I generally use Newark & Jameco.

Newark , overdoes the packing though.

 

[be80be]

Buck boost buy parts LOL I like Newark They have fast shipping and the rates are good