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sinara-hw / FMC_Shuttler

16-channel 125MS/s 16bit DAC in FMC form factor.
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FMC schematic: AD9117 DVDD output shorted to DVDDIO #22

Closed mkiepiela closed 3 years ago

mkiepiela commented 3 years ago

DVDD (internal LDO output) must be disconnected from DVDDIO when supplied from external source (V_ADJ). obraz

Disconnect and bypass DVDD output with 1 uF to GND.

obraz

dhslichter commented 3 years ago

Do we need to maintain the potential for adjustability of the DVDDIO rail? At least in my view, it is preferable to always require that the DVDDIO rail be at 1.8 V. This lowers power dissipation on the DAC as well as the FPGA driving the digital lines, and running 1.8V signals instead of 3.3V signals reduces EMI.

gkasprow commented 3 years ago

the LVDS won't work with 3.3V anyway. So we should support 1.8 and 2.5V only and this is the way I design all FMC boards. We should add 0R + 1uF to support 2.5V VADJ. We have a place for PCB for that.

gkasprow commented 3 years ago

obraz