DACs and reducing output noise

[blahblah99]

I am prototyping a circuit which uses a digital-to-analog conveter (the DAC0800 to be exact), but the outputs of it is really noisy! The output voltage levels are from 1.3V - 3.4V and the noise level is about .3V ! How would I reduce the noise level? Could the problem be at the reference inputs? I am using Iref = 5V / 4.7k for the Iref input. The 5V comes from the power supply. Please help!

 

[Gosharkss]

I have found that using seperate power and ground planes (isolate them) helps reduce noise. Also the external R/C's need to be as close to the pins on the chip as phyically possible. The tech notes of the dac should give advice on these areas.

Jim Witkowski
Chief Hardware Engineer
Cornerstone / Monitorsdirect.com

 

[Rastus]

It sounds like a ground loop. Make sure you have exactly one ground point. No more, no less. Whatever you are driving with the output of the DAC should get its ground from the DAC.

 

[blahblah99]

Do i need to supply the DAC with a 5.000V reference lvl or can I just use the 5V off the power supply?