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LTC1666 - Vref - input resistor

Hello fellows, I'm building my own DAC Eval Board and Im wondering to know ..

  1. if the External Vref  (suggested 2.5v) Can be set in a higher value?, like 5v. I only read about, adjusting Irefin current by resistor avoiding to source more than 10mA, but nothing about the Vref max limits values (May be, not exceed the sourcing values? +/- 5v). The higher Vref values in the DAC, the higher voltage range per counts (better for noise issues)
  2. About the DAC inputs, Is it necessary to put 22ohms resistor between the FPGA ouput and the DAC input ports? (I'm interfacing a Cyclone V with the DAC) Datasheet suggest to use a resistor bank in Application Information Section - Suggested Evaluation Circuit.

Thanks in advance!

[edited by: HernArg at 4:12 PM (GMT -4) on 26 Apr 2021]
Parents Reply
  • Thank you so much!!!!!

    Why sometimes the resistor between two chips interface are suggested? Just to limits the current in case you have different logic voltage levels?

    Do you have any suggestion to source the board with a split voltage +/-5 with the power source embedded on it? A read about using LTC3388 +/-5mA, Aplication Note , but a will need more current to be sure not suffer a lack of power sourcing DAC, output circuits with op amps.