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afe7222: AFE7222 Current Vout

Part Number: AFE7222
Other Parts Discussed in Thread: AFE7225EVM, TRF370333

Dears.

customer is developing AFE7222.

AFE7222 DAC has a current output, but use Voltage input GRF6413, need Current to Voltage with Common voltage tuning. Use Transformer or using a Termination with mid point DC bias?

The input voltage of GRF6413 is 1.5V.

How can I connect the AFE7222's DAC output to the GRF6413 with a 1.5V level?

Please consider the part connecting AFE7222 and GRF6413.
Schematic review Please

Thank you.

  • Henry,

    Thank you for your interest in our parts. Your post is assigned to the correct engineer.
  • Henry,

    Please refer to "output voltage compliance range" from datasheet, which shows 2.5~3.5V. You can refer to EVM schematic of Rev C on AFE7225EVM web page (www.ti.com/.../AFE7225EVM

    Page 2 of schematic shows DAC output to transformer and in this case, you'll need 3V before transformer to meet output voltage compliance range.
    Another option is page 4, which DAC output goes to TRF3703 (modulator). TRF370333 has 3.3V common mode voltage input and its circuitry is shown in page 4.

    As DAC output of AFE722x ranges 2.5~3.5V, you cannot connect the device having 1.5V of common mode voltage. But customer should be able to use 1.5V of common mode with DAC ouput by adding series cap, and this should be located after 3V with R12/R13 (example) in page 2.

    Thanks,
    KW