How to work with SCC100A pressure sensor from Honeywell?

Discussion in 'General Electronics Chat' started by Chong Chi Hou, Mar 7, 2016.

  1. Chong Chi Hou

    Thread Starter New Member

    Jan 26, 2016
    10
    0
    Lately, I have bought a pressure sensor (SCC100A) that captures data of absolute pressure. The pressure sensor is a bridge type sensor which uses wheatstone bridge to provide the output voltage and every specifications are shown in its datasheet. The problem is when I supply an 1.5mA current to the sensor, the output does not appear to be the same or even close to output voltage values given from datasheet. Is there anyone who used this sensor or faced this problem before? Thank you.
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,346
    Hello,

    Here I have found an other datasheet, with some application notes from an other manufacturer.
    You could try the application schematic from that.

    Bertus
     
  3. Chong Chi Hou

    Thread Starter New Member

    Jan 26, 2016
    10
    0
    Hi Bertus,

    Thanks for the application notes, it gives me some idea to amplify the output. May I ask you another question? Did you use this kind of sensor before? From what I understand from the datasheet, the air pressure is exerted through the P1 face of the sensor to get the output value. But, the output I obtained are negative and it doesn't even change a little when I increase the air pressure. The output only shows -0.008V (-8mv) when there's no external pressure other than atmospheric pressure. What could it be the problem here? I also have the same problem with the previous pressure sensor MD-PS002, a bridge pressure sensor.

    Darren
     
  4. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,346
    Hello,

    The 1.5 mA given in the datasheet is the maximum allowed current.
    How did you make the 1.5 mA applied to the sensor?
    Do you have a schematic?

    Bertus
     
  5. Chong Chi Hou

    Thread Starter New Member

    Jan 26, 2016
    10
    0
    Hello,

    I just make a simple circuit using transistor. The voltage source is direct from Arduino UNO 5V port. I tune the 10k POT until the current output to the load is 1mA.
     
  6. Chong Chi Hou

    Thread Starter New Member

    Jan 26, 2016
    10
    0
    Hello,

    I will try to use the circuit from the application notes you gave me and test the sensor again. I will let you know if it's workable. Thanks a lot for your patience and help. =)

    Darren
     
  7. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,346
    Hello,

    I assume you connected the sensor in place of the load. (using the pins 1 and 3).
    At 1 mA the sensor will have 5 Volts on it, as the senor is about 5K (given in the datasheet).
    As you power it with only 5 Volts, the voltage can not be reached.

    chong_scc100a_connections.png

    Bertus
     
  8. Chong Chi Hou

    Thread Starter New Member

    Jan 26, 2016
    10
    0
    Hello,

    Does it mean I have to power it with much higher voltage or get an external source that is greater than 5V? And I do not understand much about the "voltage cannot be reached".
     
  9. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,346
    Hello,

    Did you measure the voltage across the load (sensor)?
    I think you will not make the 1 mA through the sensor.

    Bertus
     
  10. Chong Chi Hou

    Thread Starter New Member

    Jan 26, 2016
    10
    0
    Hello,

    Yeap, you were correct. I measure and get 4.66V across the Vs and GND of the sensor which is lesser than 1mA. Now I'll try to increase the current supply and see if it works.

    Darren
     
  11. Chong Chi Hou

    Thread Starter New Member

    Jan 26, 2016
    10
    0
    Hello,

    I'm confused about the part that should I measure the 1.5mA before putting in the load or after? Because I tried with before putting in the load, I adjust the output from the transistor to be 1.41mA. Once I put the load series to it along with a multimeter, the current is 0 as if no current passes through. I measured the Vs and GND of the sensor, it does give me 6.39V but the output gives -16mV.

    Darren
     
  12. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,346
    Hello,

    In the given application note there is a schematic that uses a current source of about 0.75 mA.
    There is also a formula given for the output voltage:

    chong_scc100_schematic.png

    Bertus
     
  13. Chong Chi Hou

    Thread Starter New Member

    Jan 26, 2016
    10
    0
    Hello,

    Thanks, I will try to work with this circuit first.

    Darren
     
Loading...