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AD7367-5 circuit diagrams

When I used the AD7367-5 for a single-end  bipolar range-±5V analogue input signal,I couldn't 100% be sure that could that chip work in the single-ended model,since  Figure 21 about typical connection diagram in the data sheet AD7367 has some conflict with Fifure 1 in the reference  design CN0042 about the analog input signal range.Considering about I couldn't get the right output and   the AD7367-5  data sheet has some mistake that makes me couldn't trust it,can someone solve my donbt,or tell me is the circuit diagrams in the attachment correct or not ? Thanks a lot

  • Hi silence_stone

    VDrive pin the voltage supplied at this pin determines at what voltage the interface operates. This pin should be decoupled to DGND. The voltage range on this pin is 2.7 V to 5.25 V and may be different than the voltage at AVCC and DVCC, but should never exceed either by more than 0.3 V.From your circuit Vdrive is 3.3.If Vcc is 5V the Vdrive voltage should between 4.7V to 5.25V.

    Another to check is the REFSEL is tied to GND this configuration is using the external reference, an external can be supplied through DcapA. Please refer to data page 10 descriptions. This pin should be connected to Vdrive if you’re using internal reference. see typical connection diagram for your reference.

  • Hi, silence_stone.
    Vdrive can operate 2.7V  to 5.25V. AD7367-5 accept bipolar single-ended signals.Typical connection diagram attached  the AGND pin is connected to the analog ground plane of the system, and the DGND pin is connected to the digital ground plane of the system. Can you post your output and sampling rate to give us better understanding? Please take note the output coding of the AD7367-5 is twos complement and driver amplifier must be able to settle for a full-scale step to a 14-bit level, 0.0061%, in less than the specified acquisition time. Use the recommended driver amplifier in the datasheet. An op amp such as the AD8021 meets this requirement when operating in single-ended mode.
  •    Hi,Gnib.   

       Sorry really.I put wrongly a wrong previous picture,which caused your misunderstanding.When I was testing the chip,I has already connecting REFSET pin18 to D3V3. But I couldn't still get the corrent digital output.Since AD7367-5 should be controlled by FPGA,whose IO pin voltage is DV3.3,I set VDRIVE pin2 3V3.Is it right,or which way can make it work corrently?And my largest doubt is could this chip work in the single-ended model or could l just use one input VA1 and set VA2 to Ground ,or maybe I should made  all other inputs(VA2,VB1,VB2) connected to the ground? From figure below,V1 is used for a bipo analog ±5V input signal.I want to know which is the ground to V1?

  • Hi, silence_stone.

    I'm checking to see if the Dout pin is converting properly. My suggestion is let’s use DC input to check all 0’s and all 1’s. If input is sinusoidal, let's gather all data and use FFT. In this way we can check if the fundamental level is enough to drive the ADC and the system is free from noise.

  • Hi,Gnib.

      The figure below is latest tested(November 17th) AD7367-5 serial digital output on DOUTA pin1 for five range ±1/±2/±3/±4/±5V all-frequence-10kHz Sinusoidal inputs about V1.And the AGND to V1 is connected to the analog ground plane of the system.

       Since the analog signal's frequence range is from 7kHz to 16kHz,I thought I could use AD8032(the most used driver amplifier in my Lab).When the correct output couldn't be gotten,I has already replaced AD8021.But it still didn't make no difference:same digital output,same frequence,similar mess in higher input voltage.

      I also post the verilog programme in this safe website below,if you have time to check it work correctly or not.Thaks a lot for your help and patience.

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