i need to step 3.1v-3.7v(input) to 5v (500ma)(output) using mc34063
Already tried different combination of resistors, inductors and capacitors...
also tried values from mc34063 calculator but no good result.....

anyone with help?.......please

specifics will be very much appreciated....
i also need to know how the output current can be varied

thanks in anticipation

 

Various combinations of components is just about the least likely method you can use to build a switching regulator. We should start with a schematic to see if you even understand the correct topology to choose.

 

I once used several thousand monkeys to randomly assemble components to create the next generation of cell phones. Unfortunately, monkeys seem far more adept at disassembly then assembly.

olasesi: Look at Figure 6 of the data sheet. That's the closest to your needs (a step up converter). R1 and R2 need to be recalculated to get 5V.

 

How about a pot (adjustable resistor)?

 

Were the capacitors of the "low ESR" variety? Did the inductor you chose have sufficient current handling capability to avoid saturation? What frequency did you pick? What on time and off times are you using? Did you lay out a PC board or are you trying to do this on a breadboard? If you said "Hunh?", then I'm not surprised at your difficulties. Where is the schematic you are using?

 

How about a pot (adjustable resistor)?

The voltage divider to measure the output is the very least of his problems. Again where is the schematic!!??