# Need help getting at least +/-10 V from op-amp

I'm new to here and I did already some of the research but cannot really find an answer. I'm not very familiar with op-amps.

I have wired a LM358 op-amp as per the below example schematic in the MCP4725 DAC datasheet. The problem is that I'm getting only +2.7 V all the way to -2.2 V (I guess because I used 22 kΩ resistor instead of 20 kΩ) on the 12-bit DAC resolution.

However, I used bipolar supply with +/-15 V, and I was expecting the output voltage to be somewhere close to the 15 V both ways, or at least 10 V. Can somebody please explain what am I missing in order to reach my voltage output? Is the op-amp chosen wrong? If so, can you please recommend a device to use?

Thank you very much in advance for any help.

• R1 and R4 are 22kΩ
• R2 and R3 are 10kΩ
• The MCP4725 is operated with Vdd = + 5V. It is output Vout could be not higher than 5 V. The first formula gives the value 5(4095/4096) V = 4.9988 V. You have to calculate the values of R1, R2, R3 and R4 to get an output of -10 to + 10 V. You need an amplification of 4 to get -10 to + 10 V from 0 to 4.9988 V. – Uwe Dec 10 '18 at 12:11
• I see now, the datasheet stated gain is 0.5 based on 10k/20k resistors. Am i right? – Kris Dec 10 '18 at 12:14