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XTR300: Circuit Configuration Questions

Gabriel Garza45
Intellectual 2275 points
Part Number: XTR300

Hello,

We have a customer who is asking the following:

"We want use XTR300 for : +-10V , 0 to 10V, 0 to 20 mA , and 4 mA to 20 mA, all configurations  must be controlled  via software .

 

I Question , controlling  +- 10V and , 0 to 10V

                                                                              DRV

                                                                              _|_

                                                                              __   47nF

                                                                               |

          5V-----|LDO  Vout 2.5V|  -------------------•-------------------------àSET (pin4 XTR300)

              ENABLE   ---à |                                  |2,49K Ohms 1%|

                                                                           |

                                                                           |

                                                                         GND

 

         RGAIN  =10K

 

La idea is to Enable-Disable  2.5 V from LDO in order to provide 2.5 V or 0 , depending is VOUT +-10V or +10V.

This is correct  I would like to know if this is correct.

 

II, controlling   4 to 20 mA , and  +- 20 mA

a)      Single ended : Is any effect to be connected  RGAIN ?

b)      Bipolar  can be use the above circuit in order to drive +- 20 mA"

Could someone please have a look?

Thanks,

 

  • 0
    TI__Genius 11135 points
    Gabe
    Your schematic didn't come through properly...could you re-post?
  • 0 in reply to Dennis Goeke
    TI__Intellectual 2275 points
    Dennis,
    This is what was provided by the customer, and it looks just like what is posted. I have invited him to join the conversation so he can elaborate more in-depth.

    Thanks,
  • 0
    Intellectual 735 points

    The explanation of the schematic is as follows:

    In in order to control a Single Ended and bidirectional Voltage , a LDA  Vout=2.5V control Bidirectional ==>Enable ON,  Single Ended = ENABLE OFF.

    In this way the control is done via software, can be done in this way.

    Albert

  • 0 in reply to ALbert Tello
    Intellectual 735 points
    Second question :
    We want Vout +-10V and , 0 to 10V ,
    Our Arm processor Vcc= 3.3, can we use
    Vref =3.3
    VIN from 0 to 3.3 V
    Instead of 5V ?
    Albert
  • 0 in reply to ALbert Tello
    TI__Mastermind 23050 points

    Albert, Gabriel,

    You can certainly do this provided you choose the appropriate resistors for scaling. I have attached an example design that accomplishes this function. Please note that for some reason in voltage output mode the simulation does not behave as it should unless you remove the load, but I can assure you this design functions as intended.

    XTR300 Adjustable Range.TSC

    For this to work it is critical that disabling the LDO actually puts its output into a high impedance state, otherwise you will skew the response for the 0-10V range. Some devices simply enter a low power mode when disabled, but this does not truly disconnect the output. Others use a resistive feedback network to sense the output voltage, and if this is the case you would need to make sure you use sufficiently large resistors in this loop to avoid influencing the gain. 

    For the 4-20mA range you will either need to set your minimum input voltage to 660mV or add a -660mV reference voltage on Ros. 

  • 0 in reply to ALbert Tello
    TI__Genius 11135 points
    Albert
    We haven't heard back from you so we assume this resolved your issue. If not, just post a reply below (or create a new thread if this one is locked due to time-out).

    Thanks
    Dennis