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Original question:

XTR117: XTR117 (0-10V to 4-20mA)

XTR111: XTR111

Dheeraj yadav
Intellectual 640 points

Part Number: XTR111

Tool/software:

Hey Robert, I have modified the circuit as per your suggestion. Could you please verify it once before I proceed with PCB manufacturing?
Thanks for your help. 

  • 0
    Intellectual 640 points

    I am designing 0-10V to 0-20mA now. 

  • 0 in reply to Dheeraj yadav
    Intellectual 640 points

    Also I am using MMBT5087 and BSP170P Is there any other alternative in smaller package that can be used. 

  • 0 in reply to Dheeraj yadav
    TI__Mastermind 31320 points

    Hi Dheeraj,

    One change I would recommend to the schematic is connecting REGF to REGS loaded with a 2.2nF capacitor since you aren't using the voltage regulator.

    The XTR111 has an EVM, the  XTR111-2EVM, that can be used for testing if you are wanting to verify this device in your system. 

    Dheeraj yadav said:
    Is there any other alternative in smaller package that can be used. 

    The MMBT5087 is quite a small transistor as is. I'm assuming this is coming from the BSP170P. 

    We have some information on what specs are important for an external PMOS in the datasheet. The gate drive (VG) can drive close to the positive supply rail to 16V less than VVSP so you'll want a MOSFET with a maximum rating of VGS = 20V. Nothing lower. 

    Since you aren't controlling the OD, I don't think an external protection clamp will be needed.

    There's several trade off with choosing a smaller package resistor. Usually it means:

    • Lower continuous current 
    • Lower max power dissipation 
    • higher RDS On resistance

    I'd focus on the power calculations in normal operation in determining whether a MOSFET would be a good fit or not. 

    Best Regards,

    Robert Clifton