EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: symbianas on February 19, 2023, 10:26:16 am
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Hi, my car has factory ambient lighting which is very dim so I would like it to shine always at brightest setting, but I cant set it to brightest setting because it also changes instrument cluster brighness to max which I don't want to be at max.
Current supply source changes depending on "brightness setting/engine running" from 1-15V. So I would like to convert 1-15V to 5V or 3.3V for one LED maybe 60mah max power, is there a simple board converter which I could buy for this purpose?
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Converters that will start at 1V and still handle 15V is a tall order. Maybe it exists, but I wouldn’t count on it.
Additionally, if the LED driver is a constant-current source (rather than a voltage source), then you have that layer of complexity to deal with, too.
Wouldn’t it be easier to just use the fixed 12V supply and then a MOSFET or transistor to switch the enable pin of the DC-DC converter?
Also, be aware that automotive electrical systems are extremely “dirty”, with lots of spikes and noise, so you need to provide robust input protection to everything.
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How did you measure that 1-15V? I suspect the LED power is being pulse width modulated (where the voltage is always 15V, but pulsed on/off for a varying regular period depending on brightness desired), but when you're measuring it you're just seeing the average voltage level.
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How did you measure that 1-15V? I suspect the LED power is being pulse width modulated (where the voltage is always 15V, but pulsed on/off for a varying regular period depending on brightness desired), but when you're measuring it you're just seeing the average voltage level.
Indeed that is a very reasonable suspicion given that LEDs that give useful light output from 1 Volt are as rare as rocking hor.......
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How did you measure that 1-15V? I suspect the LED power is being pulse width modulated (where the voltage is always 15V, but pulsed on/off for a varying regular period depending on brightness desired), but when you're measuring it you're just seeing the average voltage level.
Yes, I was using simple multimeter so it might be average voltage level. Do voltage regulators like "step down" work on this pulse width modulated power source?
Wouldn’t it be easier to just use the fixed 12V supply and then a MOSFET or transistor to switch the enable pin of the DC-DC converter?
I might end up doing that...