AnsweredAssumed Answered

AD5450 output voltage drop

Question asked by Tejassj on Nov 4, 2016
Latest reply on Nov 7, 2016 by msamera

Hi,

 

I am using AD5450 DAC in one of my projects. I am facing a problem of output voltage drop near  Vref voltage. 

I am using AD5450 in Bipolar operation mode. The output voltage follows the equation given in Page 17 of the datasheet but the output voltage drops when the expected voltage is near Vref.

 

CIRCUIT DESCRIPTION:  

The circuit implemented is same as in Figure 45. 

R3,R5 = 2K ohms

R4 =  1K ohms 

R1,R2 = 0 ohms.

C1 = 18pF

Vref = +3.3V

A1,A2 is OPA2277. VCC and VEE for OPA2277 is +3.3V and -3.3V. 

 

RESULTS:

 

DAC code8-bit Code (D)Expected Voltage(V)OUTPUT VOLTAGE(V)
0x3fff0xFF3.32.163
0x33400xCD22.00
0x29800xA610.987
0x20000x8000.00
0x16400x59-1-1.012
0x0C800x32-2-2.026
0x00000x00-3.3-2.918

 

The expected voltage near 3.3 and -3.3 is dropping. Can this be an issue of OPA2277 being powered-up using +3.3V nad -3.3V ?     

Outcomes