DC Voltage sensing using lv-25P

Discussion in 'The Projects Forum' started by Navaneeth1285, Mar 19, 2015.

  1. Navaneeth1285

    Thread Starter New Member

    Mar 19, 2015
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    hi,
    i tried to sense 80 V dc using lv-25p, i initially tried for voltage value of 10V.but i am not obtaining voltage on the secondary side,
    primary side resistance is 10k ohm 10W, and my secondary side resistance in 150 ohm, i designed them to obtain a voltage of 3V on the secondary side.
    i tried varying the input but there is no change in the secondary side, also my dso is showing negative value..??
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Diagram please...we are not psychics.
     
  3. Navaneeth1285

    Thread Starter New Member

    Mar 19, 2015
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    i also grounded the secondary side with the +/- 12 V supply
    Untitled-1.jpg
     
  4. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Wired as shown, the primary current should be 8mA if the sensed voltage is 80V. So far so good.
    If I understand the datasheet correctly, the secondary current should therefore be 8*1000/2500 = 3.2mA, resulting in 0.48V across the 150 Ohms. How did you get the 3V figure? If you get 0V, either there's a wiring error or the IC is dead/fake.

    Edit: Looking at the datasheet again, although the conversion ratio is stated to be 2500:1000, the nominal primary and secondary currents are 10mA and 25mA respectively, implying a conversion ratio of 1000:2500. Something is inconsistent :confused:. But that ratio should give 20mA secondary current and hence 3V across the 150 Ohms, as you said.
     
    Last edited: Mar 19, 2015
  5. Navaneeth1285

    Thread Starter New Member

    Mar 19, 2015
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    hi,
    how can i test the LV25p to find whether iis working or not..?
    is there any specific method to do so..?:)
     
  6. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Nope ..you have to build the circuit to test.
     
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