AL5802 LED-Driver Works on the Breadbord, but Not on Its (seemingly Functionally Identical) PCB

If a circuit doesn't act like the schematic suggests it should, always go back to basics and make sure your "as built" circuit actually faithfully implements the schematic (no more, and no less)

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You can easily increase the gate voltage by 1.2 .. 1.4 V using a pull-up resistor and a couple of diodes:This will toggle gate voltage between 1.2 and 4.5V instead of 0 and 3.3V. There may be a small current flowing into the PIR when it drives its output high, which is undesired but which the PIR will most probably cope with.

A more elaborate solution using an extra BJT would be:simulate this circuit Schematic created using CircuitLabThis will drive the gate between 0 and 5V, as you did manually, so it should work

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What am I doing wrong? COB LED with LED Driver

You have a buck converter that can output a maximum of 32V with 36V supply, but your LED needs 31V typical, the particular sample you have might need more, the data sheet link is broken.Anyway, the key thing is that a buck converter can only output less than the supply, so it will not light with a 24V supply, and only maybe marginally supply enough even with a 36V supply to regulate well.The output voltage limit is 30V and see also note 4 (maximum output voltage is input -3V).

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Trying to split the current output of an LED driver

The LED driver regulates current, so it adjusts the voltage until the current is 20mA.If you put two LEDs in series, the LED driver will still regulate to 20mA, but the voltage required for that will be the sum of the LED forward voltages.The downside is that you need a high enough supply voltage, and any channel that has only a single LED will need to drop the voltage in the driver. If it's a buck converter, fine, but a linear regulator will heat up quite a bit

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Dim LED high level brake light

LEDs are not all or nothing, your typical LED car light has several LEDs in it, so you can have partial failures if one or more go bad. LEDs last a very long time, however they do break early sometimes, and the circuitry is not bulletproof either, so you could have a partial failure of the unit. The failure modes that would make sense are:My money would be on #2, however #3 is easy enough to test, just disconnect the wiring harness and use a multimeter to check the voltage.

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Need help finding the right transistor for a switching circuit

You are likely way better off (function wise and cost wise) using something like and LED driver eg. LM3414 with PWM input, or if you want to keep it basic you can use a DLD101, which is a MOSFET and matching BJT. With that you can drop the LM338, 1N4007, and heavyweight resistors.

What frequency are you planning on switching the diode on/off at? Both of the above will work well at