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DAC8718 unipolar single supply operation

Darko Hadzidedic
Prodigy 170 points
Other Parts Discussed in Thread: DAC8718, DAC8568

Hi,

In new design I am planing to use DAC8718. Unipolar output 0-5V is desired.

From data sheet it is not clear if negative supply is required to get output at 0V.

Output Amplifier section (page 40 in data sheet) indicate that 0.5V is min garanteed output in single supply mode.

Figure 85 is also supporting that (output 'close to 0' if unloaded). 

In other hand, elsewhere is spec 0V in single supply mode is claimed.

Thanks,
Darko 

  • 0
    TI__Mastermind 43915 points

    Hi Darko,

    You are able to tie AVSS to 0V but will need a minimum of 9V on AVdd. If you only need a 5V range with eight channels, I would recommend looking into the DAC8568. It would probably be a better fit for you and includes an internal reference. You could choose the DAC8568 Grade C/D which would give you a 5V range using the internal reference.

    Regards,

    Tony Calabria

  • 0 in reply to Tony Calabria
    Prodigy 170 points

    Hi Tony,

    We still like the DAC8718 better due to separate analog and digital ground.

    Analog supply at 9V is not an issue. Still we are not sure about performance around 0V.

    Hopw close can we get to the low rail? Do we have to use external buffer to prevent loading?

    Thanks,
    Darko 

  • 0 in reply to Darko Hadzidedic
    TI__Mastermind 46290 points

    Darko,

    You wont be able to get all the way to ground, I think the closest you will get is ~7.8mV. The outputs are already buffered so the internal DAC string is isolated from the load but if the drive strength isn't sufficient you may add a buffer.