Power solution for AD9684

Question

Hi 
 Below is the power solution proposed by ADI in datasheet AD9684 
 
 I feel the solution is a little old, can power experts provide me a solution with better accuracies and better efficiency in similar lines, my VCC is 12V, so i feel i can tie ADP2370 above also to 3.3V input requiremnet of other LDOs 
 What I am looking at is a much effiencint single IC solution or reduced IC solution using LT micro modules 
 Rails of all supplies are maintained by reference design with Vrms(noise) to 65uV and Accuracies +/- 1%

ADIApproved · Accepted Answer

Hi shyam.sunder91, 
 I apologize for the late reply. 
 To relay the response from power management team, here are the power tree solution using combined LT and ADI parts and the team's recommendations below. 
 
 "LTM8051 is a good choice. As you can see in it&rsquo;s output noise spectrum below, you would only need an LC filter to knock down the switching frequency noise below the 65uVrms noise limit. The 2.1mVrms, 1.2MHz switching frequency noise must be attenuated by an LC filter with at least 30 dB. You can set the cutoff frequency of the LC filter 1 decade lower than the switching frequency (fc=120 kHz) to achieve approx. 40 dB of attenuation (ideally). 
 
 However, I still recommend to test this in a system level to be sure, as AD9684 power rails sensitivity to noise is still unknown. Evaluating the power supply noise sensitivity such as PSMR will help in our decision on which rails need an LDO or just an LC filter. To be safe in this case, conventional approach is putting an LDO in the analog rails (AVDD1, AVDD2 and AVDD3) as these rails are more sensitive to power supply noise. Digital rails might be powered directly from LTM8051 or with an LC filter depending on the sensitivity. 
 Again, this is still conservative design as we don&rsquo;t know the sensitivity to power supply noise of AD9684" 
 Regards, 
 Xavier)

Electronic Design Services - PartnerZone

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Power solution for AD9684