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AD9148 Configuration

Product Number: AD9148

I am having a lot of trouble using the AD9148.
I set the AD9148 with a full scale of 20 mA
I try to generate a current between 0 and 20 mA on the 4 outputs of the AD9148, but I never manage to reach the value of the full scale, the value reached is 18 mA, the DAC is used with a circuit similar to the one described in page 62 of the datassent figure 78.
the other problem I encounter is when I try to generate a current of 20 mA on IoutP, I have only 16 mA on IoutP and 2mA on IoutN, whereas I am supposed to obtain a current close to 0 mA on the IoutN output.
What is the possible cause of this dysfunction ?
the other point which poses problem is the configuration of the registers, indeed when I try to add an offset current by setting the registers 2C, 2D, 2E and 2F, there is no change whatever the value written in these registers. I meet the same problem with the registers 0x50 and 0x51.

I use the DAC in the following configuration:
Afull scale = 20 mA
Data format : unsigned binary format, single port .
Is there a particular configuration for setting the registers?

Thank you in advance for your help, I do not understand the cause of these problems

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  • Hi Marco, 

    Thank you for your Answer, 

    I don't use the AD9148 Evaluation Board, i use the AD9148 with exactly the same schematic as described in figure 78 p60 of the datasheet.

    I use the DAC  in single  port mode, I'dont use DATA PORT B.

    The problem is the presence of a current of 2 mA on the output IoutN when i send DATA equal to 0xFFFF ( input DATA format is unsigned), i'am supposed to obtain a current equal to the full scale on output IoutP and 0 on output IoutN.


    Data converter team 

  • Hi  ,

    We tried the same setup using the AD9148 Evaluation Board, whose output configuration is the same as Fig. 78 page 60 in the datasheet as you described. The currents measured were expected (0mA at IoutN, 20mA at IoutP), and the peak-to-peak voltage measured is ~1V, which matches the datasheet. 

    It would help if you provide your full schematic so we can see where you are probing to obtain your output, as well as the DAC connections to see if there's anything that might cause this issue.