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I want to control the power consumption and intensity of a IR LED which is fed by a 38kHz signal. Can I add mosfets in series with different resistors (25/250) like in my schematic? Application is a battery powered beam brake.

IRLML2502PBF MOSFET datasheet here

Do I need additional resistor in gate and between gate and source? Driven by 5V Atmega328P or maybe 3.3V to lower the power consumption. Also, am I right that using mosfets instead of bipolar transistors is more energy-saving?

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    \$\begingroup\$ Place resistors in drain rather than source of FETs. | As shown you get I = V/R = (Vdrive - Vgsth)/R . \$\endgroup\$
    – Russell McMahon
    Feb 18, 2020 at 3:56
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    \$\begingroup\$ What input - output expectations do you have ? optical , electrical , control, tolerance, power current voltage . I call these Design Specs. These are more important than a schematic that doesn't work. \$\endgroup\$ Feb 18, 2020 at 5:40
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    \$\begingroup\$ MOSFET datasheet here infineon.com/dgdl/… \$\endgroup\$
    – Russell McMahon
    Feb 18, 2020 at 5:49
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    \$\begingroup\$ Drive via maybe 10 Ohm resistors. At 38 kHz you may be OK with direct gate drive - a simple gate driver may help square things up but it's not too demanding - probably. You can omit Q-high and just PWM either left or right fet gate for high or low power. | I fet approx ((Vcc - Vled-Vlowerfeton) / R ~~= (5-2-0.1) / R = 2.9/R =! 115 mA or 12 mA. Maybe a little less. \$\endgroup\$
    – Russell McMahon
    Feb 18, 2020 at 5:55
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    \$\begingroup\$ tony, sorry I dont know what you mean. I just have a Led taht should flash at 38kHz with two different currents \$\endgroup\$ Feb 18, 2020 at 6:22

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