How do I do I output an analog signal from 0V - 10.67V using a DAC and provide a Vcc of 5Vdc that can supply at least 3.5 Amps to the rest of my circuit?
I am trying to make a circuit that outputs a specific voltage in the range of 0V - 10.67V . This circuit is also part of a larger circuit with a current draw of 3.5 Amps. I'm using an Atmega328P and an MCP4922 12-bit DAC powered by a 5V AC/DC wall adapter. My goal is to be able to send the Atmega328P a number and have the MCP4922 output the corresponding voltage which I am able to do but I cannot make the MCP4922 output a voltage higher than (approaching but not equal to) Vcc. I have a couple ideas on how to get to the 10.67V so far but I am not sure which would be best or if I am even on the right track.
MCP4922 datasheet: here
Keep the circuit and power supply "as is". Except at the Vout of the DAC, add on an op amp configured for single side supply operation in a non-inverting gain circuit like shown in this example from microchip.com.
Then I would set R2 and R1 so that the Vout = Vin * Gain. Where Gain = 10.67 / (Vref of the DAC). I would reduce my calculations for the DAC in half. Where previously, if I wanted to output 2 Volts, I would tell the DAC to output 2V. Now, if I want to output 2V, I tell the DAC to output 1V and the opamp will double it to 2V. By the same logic, if the DAC outputs 5V, then the op amp will convert it to 10V.
Is this doable? Good idea?
Get rid of the AC/DC wall adapter and switch to a 12Vac transformer. Take the 12Vac output and split it in two +/-12V lines. Take one line and use a (full wave?) bridge rectifier with a smoothing capacitor to convert the 12Vac to 12Vdc. Take the other line and use the 12Vac with an op amp in a non-inverting amplifier configuration. Where the Vout of the DAC would go to the (V+) of the op amp. And where the desired gain would be = 10.67 / (Vref of the DAC).
*My apologies. I made an edit and removed the second part asking about how to step down 12V to 5V to make this topic more specific.