Very low noise DAC

Question

Hi, 
 I need a low noise DAC for a precision low-frequency (<500Hz) application, resolution >= 16 bits, 3.3V, SPI 
 I am thinking of using the LTC6655BHMS8-2.5 as a reference, but trying to find a DAC that doesn't swamp its 400nVpp low frequency (0.1-10Hz) noise is difficult. 
 In your product selector guide the LTC2641 is shown as a low noise DAC but its datasheet doesn't provide much information on noise, what is its 0.1-10Hz peak-peak noise? 
 Is there a lower noise output part that you can suggest? 
 (The AD5780 has 1.1uVpp typical) 
 
 Many thanks, 
 Dominic

DMW · Accepted Answer

Thanks for the reply. 
 The AD5791 is 1.1uV i.e. much worse than AD5512 The AD5541/AD5542 seem to also be a possible choice 
 
 Thanks

mehdiaghayi · Answer

Hello DMW, 
 AD5791 has better Output Noise Spectral Density in comparison with AD5542a (7.5 < 11.8). Don't forget that portion of indicated noise for AD5791 is contributed by AD8676 opamp. 
 regarding the DC noise they have same value. but the noise value has been scaled by reference voltage. 
 as a result, AD5791 is a better choise for output voltage higher than 5v. however, design is going to be more difficult because of the need for at least 5 volts negative rail supply. . If you don't need really 20bits resolution and the output voltage swing is below 5v and want to avoid negative voltage, I would say AD5542a is a better choice. 
 Regards

Electronic Design Services - PartnerZone

Very low noise DAC

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