I’m working on a TV-B-Gone type project using an ESP32, and I want to drive 2 SFH4544 and 1 SFH4545 IR LEDs at maximum possible output.
I have two power supply options:
5V 2A
3.5V–4.2V 3A (realistically I can only draw up to 2.5A for safety reasons)
My goal is to achieve maximum range with minimum power loss.
Some questions:
Should I connect the LEDs in series or parallel for best efficiency and performance?
Which MOSFET or transistor would you recommend to drive these high-power IR LEDs from an ESP32 GPIO safely and efficiently?
What’s the most efficient circuit design (current-limiting resistor, direct drive with pulsing, etc.) for this case?
Is it better to use the 5V 2A or the 3.7V 3A supply, considering the LEDs’ forward voltage and total current?
I want to push the IR LEDs as hard as safely possible for max brightness and range. Any schematics, part suggestions, or advice would be greatly appreciated.
The data sheet will tell you how much you can drive them. The forward voltage will be just under 3 volts. The brightest will be about 1A pulse less than 100us but that is just a SWAG as you did not give ambient conditions, duty cycle etc. Without knowing the rest of the circuit or how the LEDs will be cycled I cannot give an accurate answer on the power supply. You need to give us more information. Here is a simple schematic showing the LED circuit. Be sure to use R2 as it guarantees the MOSFET will be off during reset etc.
If you want to reach near 1A max pulse current, you can't drive them in series with your power supply options.
I think the most convenient way to power these would be 3V battery without series resistors (like some commercial remote controls do). Keep duty cycle low for best efficiency.
Be aware when prototyping that the pulses are some microseconds max, accidentally writing pin high would burn your LED in milliseconds.
