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XTR 110

Purushottam Pawar
Intellectual 400 points

Other Parts Discussed in Thread: XTR110

Hi,

I have implemented application circuit  provided in the datasheet  on breadboard for 0 to 10 V input and 4-20 mA output.

Supply voltage- 24V 

PMOS used - J176 (gate-source breakdown voltage of 30 V)

Input voltage range 0-10 V (through power supply)

But for the provided input voltage range, output varies from 6.31 mA to 18 mA.

I have changed the configuration for 0-5 V input but in that case also output is somewhat similar to previous case.

I tried with  zero and span adjustment as per mentioned in datasheet. But found no change. 

I have to use 0-5 V input and 4-20 mA configuration.

Please suggest!!

Thanks,

Paddy

  • 0
    Guru 21975 points

    Paddy,

    I'm sorry you are having difficulty with the XTR110. Can you please explain how you are measuring the output current? Are you measuring the voltage across an output load resistor? What is its resistance value?

    Please recheck all the connections shown in figure 1 of the data sheet. Are you connected as shown in figure 1?

    Be aware the the power dissipation capabilities of the J176 may not be sufficient. What package type are you using? This may not be a cause of your issues but common use of the XTR110 would normally require a MOSFET with higher power dissipation capability.

    Regards, Bruce.

  • 0 in reply to Bruce Trump
    Intellectual 400 points

    Thanks Bruce for your quick and kind suggestions!!!!

    I did connections as shown in figure 1 and measuring voltage across  an output load resistor (Value of load resistor is 10 ohm).  

    I have assembled the same circuit with 3 different XTR 110 and every time found the same results. 

    I am using TO 92 package of J176.

  • 0 in reply to Purushottam Pawar
    Guru 21975 points

    Paddy,

    The 10 ohm resistor load resistor is functionally okay but could pose a measurement issue. Be sure to measure directly across the resistor (Kelvin connection). Contact resistance in a breadboard might add changing resistance that could make the reading unstable or variable. It might be wise to change to a larger resistance value such as 100 ohms so that you are reading a larger voltage level.

    A plug-in type breadboard or poor socket contact could cause problems at the connection of pin1 and 13. Be sure this connection is very secure. The ground connection at pin 9 can also be vulnerable to series resistance.

    Check voltages expected at various nodes. Connected for 0-10V = 2-20mA...

    • 0V at pins 2, 5, 9
    • 10V at pin 3

    As you can see from this, my best guess is that you have some connection error or poor connection so check all points. Also, have you tried changing the FET? Perhaps there is a problem here.

    Good luck and please report.

    Regards, Bruce.

  • 0 in reply to Bruce Trump
    Intellectual 400 points

    Hi Bruce,

    Thank you very much for your kind co-operation.

    I  replaced 10 ohm load resistance with 100 ohm and measured the output  across this resistor.

    Voltage at pin no.  16,  1, 13 = 24V

    Voltages at  pin no. 2,5 and 9 are 0 V.  But there is some trouble with the voltage at pin no. 3. 

    I have checked 3 IC's and observations are as follows.

    1.  First IC-- Vref  in (Voltage at pin no. 3)= 10 V 

                          Vref adjust (Voltage at pin no. 11)=2.45 V

                          Output voltage across 100 ohm load resistor= For 0 V  input - 0.64 V 

                                                                                                               For 10 V input - 1.93 V

    1.  Second IC-- Vref  in (Voltage at pin no. 3)= 4.3  V 

                                Vref adjust (Voltage at pin no. 11)=1 V

                                Output voltage across 100 ohm load resistor= 0 V  input - 0.67 V 

                                                                                                                    10 V input - 1.59V

    1.  Third IC-- Vref  in (Voltage at pin no. 3)= 17.35 V 

                            Vref adjust (Voltage at pin no. 11)=0 V

                            Output voltage across 100 ohm load resistor= 0 V  input - 0 V 

                                                                                                               10 V input - 0 V

     Currently I do not have any other alternate option to J176.

     I have ordered some of the recommended FET's mentioned in datasheet. 

    To avoid the loose connections issue I have assembled the circuit  on general purpose board.

    Please suggest!!!!

    Regards,

    Paddy

  • 0 in reply to Purushottam Pawar
    Guru 21975 points

    Paddy,

    Do you have anything connected to the reference adjustment, pin 11?  I recommend that you make no connection to this pin. For most applications, no trimming is required.

    With no connection to pin 11, you should get 10V out on pin 3. If not, something is seriously wrong, so that's a good place to start your troubleshooting.

    Regards, Bruce.

  • 0 in reply to Bruce Trump
    Intellectual 400 points

    Hi Bruce,

    I have not connected anything to reference adjustment, pin 11.  

    Even though I am getting 10 V at pin no 3 in first case, the output across load resistor is 0.6 V to 1.93 V.

    Now only thing remaining  is the replacement of J176 MOSFET.

    I will update you the results when I am done with this.

    Thanks & regards,

    Paddy