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Tuesday, October 13, 2009

Laser Diode Driver Circuit

This is a design circuit for laser diode driver circuit that can be implemented using voltage-controlled current source. This is a simple circuit that is linear laser diode driver gives cleaner drive current than a switched (PWM) drivers. This is the figure of the circuit.

A Howland current pump with a current booster is used as the basic of this laser diode driver. Q1 is used as the current booster on the output of a R-R CMOS OPA350 op amp (U2). Voltage drop across a shunt resistor (RSHUNT) in series with the laser diode is measured differentially to sense the current. An analog voltage from a potentiometer of from a microprocessor controlled DAC can be fed to VIN to control the laser diode current.

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