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Original question:

LM317 used as a Constant Current Source

LM317: LM317

Pranav B
Prodigy 10 points
Part Number: LM317

Tool/software:

Need to have a reference circuit for using LM317 as constant current of 1mA.

application - will be use to sense temperature from PT100 sensor. (3 wire)

Voltage used is AA battery - 3V.

  • 0
    TI__Expert 5470 points

    Please follow the applications circuit in fig 18 of the datasheet and use a 1250Ω resistor at the output instead of 24Ω. This sets the output current to the desired 1mA. Connect the RTD to where the battery is connected in this schematic. Input and Output capacitors are not required. Please note that the minimum recommended output current for this device is 10 mA and you shall be operating below this limit.