Re: How quiet are ADCs and DACs on micro controllers?



Hello Rene,


There are some data sheet entries stating the SNR, for example for the 16-bit converter on the MSP430F2013. However, it isn't too clear what kind of code it was running at that time and in my experience it is rather difficult to get that information out of manufacturers.

Anyone with noise experience? How about the DACs? How much noise would be riding on them if you held their data register constant and looked at the analog out?

Other than for mundane 8-bit jobs I always used external ADC/DAC in the past but with newer devices there are often not enough port pins to do that. I could measure it and still hit a snag. Just want to avoid the situation where I am told after tons of work "Yeah, but you should not have accessed the HW multiplier thingie during integrate and hold" or something like that.


Much is dependent on your layout. I'm not too familiar
with the mentioned family to go into details. Try
averaging to reduce the noise if cpu-time permits.


The layout will be RF engineering style. I am more concerned about things on the chip itself. That's behind the bond wires where there is not much I can do other than averaging and making sure that segments of the uC are not jerked on and off in terms of power consumption.

--
Regards, Joerg

http://www.analogconsultants.com
.



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