Why AD4841 is not rail-to-rail?

Hi everyone

I am using AD7682 as an ADC and using its external voltage reference mode.

The external voltage reference is buffered by AD4841-2 dual OpAmp.

I power the AD4841 with +- 5.040V power supply. The voltage reference is +5.006V.

However, after buffered by AD4841, the +5.006V reference only becomes +4.386V.

It seems that AD4841 is not rail-to-rail,

Could anyone help on this?

Really appreciate.

Regards

Richie CHEN

Parents
  • 0
    •  Analog Employees 
    on Jan 3, 2013 9:40 PM

    Hello Richie,

    The problem is that you are exceeding the input voltage range of the ADA4841-2, which is on a +5V supply is -0.1V to 4V. If you want to use the ADA4841-2 to buffer the reference you’ll need to increase the power supply to at least 1V above the reference voltage.

    I hope this helps.

    Regards

    John

    cid:image003.jpg@01CDE9A7.01E7C870

Reply
  • 0
    •  Analog Employees 
    on Jan 3, 2013 9:40 PM

    Hello Richie,

    The problem is that you are exceeding the input voltage range of the ADA4841-2, which is on a +5V supply is -0.1V to 4V. If you want to use the ADA4841-2 to buffer the reference you’ll need to increase the power supply to at least 1V above the reference voltage.

    I hope this helps.

    Regards

    John

    cid:image003.jpg@01CDE9A7.01E7C870

Children
No Data