I am going to the customer lab on this problem tomorrow. I will take these ideas with me and then work out getting this power supply to work. I'll write up a reply report as to what the result is after I get it working. I will then make up a final copy of the circuit on my prototype setup here and publish a working result on my 8052.com web page (with code) in the next week or so.

Thanks for all the input, and questions.

Here are a couple of answers to some of the questions asked already........................

I will be putting this example problem on a Cygnal 'F226 processor when I publish it. The Cygnal 'F226 will have a push-pull output on the timer pin. Right now I have to admit that the customer I am working with is asking me to put it onto another brand of controller that will remain unnamed here.

The processor this algorithm has to run on is rather busy already. It has an 8MHz instruction cycle rate and I guess it is busy loaded at about 40% of total bandwidth. It manages an 8x2 LCD, scans a 2x4 key matrix, runs a 1 KHz interrupt to produce two output waveforms that are sub-multiples of 1 mSec timing resolution at 60/40 duty cycle timing, and it monitors three analog inputs (in addition to the High Voltage input). Two of the analog inputs interact with user settings from the key pads and cause changes in the two output waveforms. I am not at liberty to give more detailed information at this time.

I thought the project of doing a software controlled switcher was so interesting that I want to spend a day putting in on a real 8051 type chip to share it here after it is done.

Mike Karas