amplifiermicrocontrollervoltage
I have a 0-3.3V output that I wish to amplify to 0-10V.
I am using an 8-bit R2R resistor ladder connected to a National Instruments USB-6501 digital I/O device.
The application is to control a linear actuator via a controller that requires a 0-10V command signal therefore I need to amplify the output from the resistor ladder.
Would be grateful for any advice on how this can be achieved, thank you.
OK, so you basically need an audio amplifier circuit but without the high-power stage. So here's a op-amp + Sziklai output stage amplifier that should supply 50V swing at low currents.
It simulated OK in my head, but I tried it in LTspice to get the supply current and transient response, and tune the feedback for stability.
Blue trace is 3V supply current, and red is 50V supply current. The other two are input and output.
You could save some quiescent current by using a 1.5 V supply for the emitter voltage instead of the 40k+40k divider. 20k to a normal rail-splitter circuit would work.
Have you got a full schematic to take a look at? I used the CC2650 Launchpad's debugger (XDS110) to program a custom board recently, and I removed all the headers however between the debugger and the EM. I would suggest doing the same on your debugger.
Best Answer
One approach is to use a non-inverting amplifier at the end of the DAC output, supplied by atleast 10 volts.
The DAC output in this case will be \$V_{in}\$
\$ V_o = V_{in}( 1 + R_1/R_2)\$
Lets say we want \$V_o = 10V\$ , when \$V_{in}= 3.3V\$
\$10 = 3.3(1+R_1/R_2)\$
\$10/3.3-1 = 2.0303 = R_1/R_2\$
So one way to go at it , is make a non-inverting amplifier with a gain of roughly 2, by using 2Kohm for feedback resistor \$R_1\$ and 1Kohm for the other resistor \$R_2\$
8-bit resolution means the range is 255 discrete voltages. So 10V/255 bits = \$ 39.2mV\$/ bit