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Electronics => Beginners => Topic started by: FrankT on May 14, 2013, 04:59:18 am

Title: Selecting drive current for opto reflective sensor
Post by: FrankT on May 14, 2013, 04:59:18 am

I'm building a circuit using a SFH 9240-Z Reflective Interrupter (http://www.mouser.com/ds/2/311/FH9240_Pb_free-39520.pdf (http://www.mouser.com/ds/2/311/FH9240_Pb_free-39520.pdf)) and I'm not sure what current I should be driving the emitter at.

The data sheet mentions absolute maximum If=50mA.  The parameters use If=20mA when measuring turn on/off times, and If=50mA when measuring Vf.  I know that the lower the current, the longer the emitter will last.

Is there a way to calculate the optimal emitter current?

Title: Re: Selecting drive current for opto reflective sensor
Post by: David_AVD on May 14, 2013, 06:16:12 am

I'd probably use 10mA but check for correct operation at 5mA as a safety margin.