R2R ladder with OPAMP and controller

Thread Starter

Nidhi123

Joined Jul 24, 2018
13
Hello,
Please find herewith attached an Image of a block diagram.

In this now we are facing that we get output voltage which is range from -2.8 to -0.6 V for (111 to 001 combinations).

But in our application, we want -5V as output. so is there any option to get -5V as output? The controller which we are using is operated on 3.3V. so can we do this by using OPAMP as a differential?

Please guide.
 

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crutschow

Joined Mar 14, 2008
27,696
is there any option to get -5V as output?
Increasing the value of the 20kΩ op amp feedback resistor will increase the output voltage..

You can't get a negative output without a negative voltage, so you will need a negative supply for the op amp of a least -5V.
 

Ian0

Joined Aug 7, 2020
3,186
Something not quite right about that R-2R ladder - bit 0 seems to have no other connection than a resistor to ground.
 
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