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icp(integrated circuit piezoelectric) acceleration sensor signal conditioning

aseok tag
Intellectual 290 points

Hello

As a part of my project , i should work with icp acceleration sensors.

It is mentioned in it's document that for proper operation of this kind of sensor , it need's 2-20mA constant current excitation with 18 to 30 VDC supply.

How can i implement this excitation with opamps ? 

Does this constant current excitation make any obvious difference with respect to other piezoelectric sensors?

Please guide me through the design of it's supply.

Thanks.

sensor specification :

Signal Conditioning Basics for ICP® & Charge Output Sensors :

Does this circuit meet our purpose ?

  • TI__Genius 12325 points
    Hello,
    The circuit schematic that you show is a charge amplifier which is commonly used for un-amplified charge output accelerometers. The sensor that you have linked to is internally amplified and only needs a voltage source in series with a current regulating diode as a power supply and op amps are really not needed for the power supply. This is shown in Figure 7 of your second link.
  • in reply to John Caldwell
    Intellectual 290 points
    Thanks for your answer, but is it possible to design a current source with opamps(excluding these diodes) ?
  • in reply to aseok tag
    Intellectual 290 points

    Is it possible to use something like this?

  • in reply to aseok tag
    Intellectual 405 points
    Hi Aseok

    As John has said you don't need to use op amps at all. A current regulating diode is enough. I have use the SST511 from Linear Systems in the past. One side is connected to the power supply and the other side goes to the sensor. This part delivers 4.7mA+/-20% constant current. If you need more current (longer cable) you can parallel them but in general you won't need to do this. Figure 7 in the ICP reference doc shows the connection of the CRD to the power supply and sensor. I used +24V as the power supply but as the article says anywhere from +18V to +30V may be used. Don't forget the AC blocking capacitor (the decoupling cap shown) since the sensor will sit at about +10V DC.

    regards
    Steve