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I was thinking if i use dc-dc step down converter on infrared LED 5 mm, 940 nm and The supply voltage for the DC to DC step down is 5 V from a smart phone charger then I will set it on 1.4 V exactly what IR LED needed voltage. I will use five IR led in parallel. I'm thinking now about the current that the light might break or burn out because look the detail about DC to DC max current is 3 A. But the way I will use it on my mini CCTV camera.

Here the details of the item I will use :

  1. DC-DC LM2596 LM2596S input 4V-35V output 1.23 V - 30 V step-down power supply.
  • Module property: Non-isolation buck
  • Rectification mode: Non-synchronous rectifier
  • Input voltage: 3.6 V - 46 V
  • Output voltage: 1.25 V - 35 V
  • Output current: Rated current is 3 A,
  • Conversion efficiency: 92% (highest)
  • Switching frequency: 65 kHz
  • Output ripple: 30 mV (maximum)
  • Load regulation: ±0.5%
  • Voltage regulation: ±2.5%
  • Work temperature: -40° - 85°

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  1. IR Infrared LED 5mm 940 nm

  • Dominant Wavelength: 940 nm

  • Emitted Color: Infrared receiving

  • Forward Voltage (V) : 1.27 - 1.4 V

  • Reverse Current: 10 μA

    enter image description here

Transistor
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MARK
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1 Answers1

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No, you should not attempt to drive LEDs with constant voltage. This has been addressed here over and over again.

Elliot Alderson
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  • I would say over and over and over and over and over (I got cramp now so I'll stop) – Andy aka Sep 05 '21 at 12:53
  • How about the 3w infrared led light? Emitted Color: 850nm Infrared IR Viewing Angle: 120 degrees DC Forward Voltage (VF): 1.5-1.7V DC Forward Current (IF): 500-700mA Maximum Pulse Voltage: 2.2V Maximum Pulse Current: 800mA, did you have circuit diagram for it? – MARK Sep 05 '21 at 13:18
  • Sure, there are many possible circuits. You could use a 12V battery with a resistor of about 20 ohms in series. Or a 5V source with a resistor of about 7 ohms. But you should probably do some research on constant-current LED drivers to find a solution that really meets your needs. – Elliot Alderson Sep 05 '21 at 13:32
  • What if i use LM317 for constant current and voltage or i will buy ready to use LM317 DC-DC step-down DC converter circuit board power and set it on required voltage need on 5 IR LED 5MM, 940MN. ? But I'm gonna use 5v smart phone charger? Here the details of the board Link : https://youtu.be/iuMngik0GR8 – MARK Sep 05 '21 at 13:44
  • Output Current : 1.5A ( minimum ), 2.2A ( typical value )

    Input-output voltage difference (VI-VO): 40Vdc ( max )

    Adjustable output voltage range : 1.2 ~ 37V

    Working temperature : -55 C to + 150 C

    Current output : 1.5A

    Voltage Input : 4.2 ~ 40 V

    Operating temperature : 0 C ~ 125 C

    Characteristic frequency : 100 (MHz)

    Module size : 35.6 (mm) x16.8 (mm)

    Input mode : VIN input positive level , GND input negative

    Output : VOUT output positive level , GND output negative

     – MARK Sep 05 '21 at 13:44
  • The LM317 is not a "DC-DC step-down DC converter", it is a linear regulator. You keep talking about "set it on required voltage"...that's a bad idea. – Elliot Alderson Sep 05 '21 at 16:11