Shall i Feed 0-2.5V AC signal to AD5750-1 at Vsense+ and Vsense- ?

Hello,

I am designing a product to measure current using Current Transformer and my final output should be 4-20mA or 0-20mA or 0-5V or 0-10V based on primary current. So I plan to use AD5750-1 to my application.

In my design, current sense transformer output is 0-2.5V AC which is sensed using burden resistor across current transformer output. I want that to be fed to input of AD5750-1.

Can i feed my 0-2.5V AC signal to input of  AD5750-1 at Vsense+ and Vsense- ? If not, What would be the best practice to achieve this ?

Regards,

Winiston.P

Top Replies

    •  Analog Employees 
    Jan 27, 2020 in reply to winiston.p +1 verified

    Hi winiston.p,

    1) You will also get an AC signal at the output but that depends on how fast your AC signal at VIN changes. For the mentioned figures, they are showing the output responses based on a step…

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  • 0
    •  Analog Employees 
    on Jan 24, 2020 12:03 AM

    Hi,

    You need to feed it to the VIN pin of AD5750.

    Vsense+ and Vsense- are should be connected across the load of the VOUT to ensure proper regulation.

    Cheers,

    Ivan

  • Hi,

    Thanks for replying. I hope that "VIN" pin is only for DC(0-2.5V DC) input in AD5750-1. 

    Shall i feed 0-2.5V AC/50hz signal to VIN pin of AD5750-1?

    If I feed AC signal(0-2.5V AC/50hz) to VIN pin, will it damage IC ? How AD5750-1 will perform for AC signals?

    Regards,

    Winiston.P

  • Hi Isantos,

    Thanks for your reply. I referred figure 17, 18, 47. I hope that It works well for 50 HZ signals and can get stabilized DC voltage/current (0-5V or 0-10V and 0-20 mA, etc). Can you please clarify below three questions.

    1. If i feed AC signal to "VIN" pin, Can i get DC voltage at VOUT and DC current at IOUT ?

    2. If i want to feed AC signal to "VIN", how to connect neutral of AC input signal? Can i connect Neutral of AC input signal to DC ground ?

    3. What is the performance of  AD5750-1 when i feed single supply?

    Regards,

    Winiston.P

  • +1
    •  Analog Employees 
    on Jan 27, 2020 8:13 AM in reply to winiston.p

    Hi ,

    1) You will also get an AC signal at the output but that depends on how fast your AC signal at VIN changes. For the mentioned figures, they are showing the output responses based on a step response at the input.

    2) I'm not sure whether you should or shouldn't connect the AC line neutral to the DC ground, you may refer this to other experts especially on safety requirements of equipments. One more thing, if the signal coming from the CT is an AC signal, then you might want to use an amplifier to induce a DC offset and scaling (if required) so the AC signal fits with the whole input range of VIN. Or, you could also use a full wave rectifier after the CT to guarantee that you have a unipolar signal at VIN.

    3) Unfortunately the performance was not characterized using single supply, so we cannot really guarantee what is in the specification table for unipolar supply.

    Cheers,

    Ivan 

  • Hi Isantos,

    Thanks for your detailed reply. It is cleared my doubts.

    Regards,

    Winiston.P

  • 0
    •  Analog Employees 
    on Jan 28, 2020 6:02 AM in reply to winiston.p

    Hi ,

    I just remembered that you can also check AD5751 if you only require unipolar output ranges. The specification table is also specified using unipolar supplies.

    Cheers,

    Ivan

  • Hi Isantos,

    Thanks. AD5751 is uni polar output. But still i have a problem with AC input signals. I just plan to use (TLV172 based) below circuit to convert AC to DC with scaling. This is precision full wave rectifier circuit.

    I have two question here.

    1.  How do i adjust gain here. If i adjust R1 & R2 , will the gain be adjusted?

    2. My input is Vi (AC/50HZ). If i use 10uf or 22uf capacitor at output(VO), will it be converted to pure DC signals?

    Regards,

    Winiston.P

Reply
  • Hi Isantos,

    Thanks. AD5751 is uni polar output. But still i have a problem with AC input signals. I just plan to use (TLV172 based) below circuit to convert AC to DC with scaling. This is precision full wave rectifier circuit.

    I have two question here.

    1.  How do i adjust gain here. If i adjust R1 & R2 , will the gain be adjusted?

    2. My input is Vi (AC/50HZ). If i use 10uf or 22uf capacitor at output(VO), will it be converted to pure DC signals?

    Regards,

    Winiston.P

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