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I have a laser diode driver chip that can produce DC currents up to 200mA. The current is adjusted by a potentiometer on the driver chip. The driver chip has four pins:

  • inputs: GND, SUPPLY
  • outputs: LD+, LD-

My approach was similar to the suggestion here. But how can I measure the current leaving the outputs? Can I connect a large (how large?) resistor between the LD+ & LD- pins and put a shunt across this load resistor, then measure the voltage across the shunt? Do I need a load at all? I don't want to connect the laser diode in case the current exceeds the diode ratings.

EDIT: Spec Sheet of the driver, if it helps.

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  • \$\begingroup\$ Hi, welcome and thank you for your question. posting model numbers and datasheets is allowed and recommended for situations where they could be relevant to answering the question. You might be confusing this with the rule that generally discourages asking for product recommendations. \$\endgroup\$
    – nanofarad
    Commented May 13, 2020 at 15:16

2 Answers 2

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I'm sorry but its not clear what you want. I'm assuming you want to measure the current coming out of the laser diode.

If that's the case, Just connect a resistor across the diode and measure the voltage. With this you know know the current coming out of the laser diode.

Your minimum resistance value should be high enough to withstand highest current of the diode (200mA).

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If you have access to a digital multimeter, you can wire the meter in series with whatever you want to measure the current through. Check out this link for more specifics:

https://www.electronics-notes.com/articles/test-methods/meters/how-to-measure-current.php

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