Constant Current Laser Diode Driver Circuit Using OPA2350 OpAmp

  • Rajkumar Sharma
  • 15869
  • easy
  • Tested

The voltage-controlled current source circuit can be used to drive a constant current into a signal or pump laser diode. This simple linear driver provides a cleaner drive current into a laser diode than switching PWM drivers. The basic circuit is that of a Howland current pump with a current booster (Q1) on the output of a R-R CMOS OPA2350 op amp (U1). Laser diode current is sensed by differentially measuring the voltage drop across a shunt resistor (RSHUNT) in series with the laser diode. The output current is controlled by the input voltage (VIN) that comes from Trim pot PR1.


  • Supply 3,3V DC
  • Load Up to 300mA
  • PR1 Trimpot Current Adjust


Parts List





  • Mitek

    looks interesting. Can you say ZD1 voltage level ?

    3 years ago
    • admin

      You can use LM385-1.2 voltage reference from but the circuit will work without it.

      3 years ago
  • rawan alsaadi

    is there any equivalent ic instead of opa2350?

    2 years ago
  • Damian W

    F.e MCP6232T from Microchip

    2 years ago
  • naved

    i have to design a laser diode circuit for dental application in pain relief.
    please help me in circuit design process

    9 months ago
  • Edu Blumer

    Can you say ZD1 voltage level ?

    3 months ago
    • You can use ZD1 -> 1.05V zener diode.

      3 months ago

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