automatic VDD regulation

[Mosaic]

Is there an approach to have a PIC like a 16F688 self regulate it's supply voltage?

Since it operates on 2 thru 5.5V, if I have a 7VDc incoming through an RC delay couldn't the PIC PWM a (weak pull up) pass FET based on it's comparator being referenced to a precision reference?

Once the PWM frequency is hi enough a small RC filter can smooth the power.

Anyone care to ring in on this pls? Nigel, Eric, Mike(s), Colin(always got a hack) etc?

 

[Mike - K8LH]

Have you considered using one of the "HV" devices which have a built-in shunt regulator?

 

[Mosaic]

Yes...That's a possibility. But I was hoping to use the Oshonsoft Basic to do this. It doesn't yet support those PICs.

 

[be80be]

Check this out **broken link removed** and the rest of the story **broken link removed**

And this page is better **broken link removed**

It shows the same circuit as the first but has some more cool stuff.

 

[Mosaic]

Thx burt!

 

[Mr RB]

It's an interesting idea but is it really worth all that complexity?

If you have 7v input and need 5v the efficiency of a SMPS buck may be equal or even less than a good linear regulator. So you don't get any gains.

Instead of all the external parts and things to go wrong with a buck regulator, you could just use a low quiescent current low dropout 5v regulator, a simple 3pin device, and many are internally protected for overcurrent, overheat and even reverse battery connection.