Best Part to Use?

[King of Camelot]

Ok, my problem is I have a voltage regulator, that i need to set depending on some input from a microcontroller. Now, the voltage regulator i have picked out is set by either leaving a pin on it unconnected, or have it connected to a Ground on the voltage regulator, allowing it to set several different voltages. Now, what would be the best way to have input from the microcontroller change which ones are connected to that ground, and which ones aren't? I a new to electronics, so any help would be much appreciated.

 

[Phasor]

Can you tell us exactly which regulator you have (ie, the part number)?

 

[King of Camelot]

Ok, I decided to scrap that idea and use an Digital to Analog convertor instead of a regulator to get my voltage, now, the only problem is that I either need one that can output up to 12 volts, or something to boost the voltage from one I was looking at to about 11.4 volts from 5.1 volts. Any suggestions?

 

[Phasor]

11.4 volts from 5.1 volts.

Perhaps an op-amp, as a non-inverting amplifier will suffice.

 

[stevez]

What is the load on the 11.4 volts, in terms of milliamps, amps,...?

Can you select a microcontroller that has an analog output?

With appropriate considerations for the current/voltage/power, it would seem that a single transistor with appropriate voltage divider on the input and proper power supply might also work.

More of a question to others: could a simple LM317 with the appropriate external resistors, be "adjusted" via an external current source (the analog output) so that there is some regulation for a varying load?

 

[King of Camelot]

Thanks for your advice, I decided to use an op-amp like Phasor said because it sounded easiest to do. Now, I have yet another problem. I am using an ADC. Now only problem is the voltage I want to convert is between 6-12 volts which is too high for the ADC. I was thinking I could drop the voltage 6 volts so it stayed on the 6 volt scale, I would just add 6 on to the voltage taken from the ADC. What could I use to drop it down 6 volts? If I used a resistor, how would I determine the ohms if it is going straight to a pin on the ADC?