Hello everyone, I am new here but not to electronics.
I have run afoul of something I am not finding enough information to come up with a solution for, I am hoping you wonderful folk will be able to help.
I am working on the restoration of a 1965 Chevrolet C10 truck, this particular bit has to do with the dash illumination. The dash illumination will be mix of small bulbs and LEDs. They will all have a common ground and dimmed power feed, I am not opposed to having a separate power for the bulbs and LEDs, but all will be wired in parallel and the number of LEDs is not known. The driver must be able to handle changing numbers of LEDs without adjustment, although it is acceptable that the brightness of the LEDs be reduced slightly by the addition of more LEDs in the circuit.
So I've done LED drivers before in design, but in terms of building them I have only ever used display drivers that handle a single LED per driver and have a common return back to the chip. I have made designs for buck drivers, but never built one yet. I do know that the best way to drive LEDs is in series, and that driving them in parallel has several drawbacks. I also know that a constant current buck converter will not be a safe option for this configuration because the load will not be balanced with the LEDs wired in parallel.
Given these design criteria, I don't know how to drive them.
The best theory I have at this time is to PWM a P-FET on the high side, low pass filter, and have individual current limit resistors at each LED. This does not seem like the best way to do it though.
Any help is greatly appreciated,
Mike
I have run afoul of something I am not finding enough information to come up with a solution for, I am hoping you wonderful folk will be able to help.
I am working on the restoration of a 1965 Chevrolet C10 truck, this particular bit has to do with the dash illumination. The dash illumination will be mix of small bulbs and LEDs. They will all have a common ground and dimmed power feed, I am not opposed to having a separate power for the bulbs and LEDs, but all will be wired in parallel and the number of LEDs is not known. The driver must be able to handle changing numbers of LEDs without adjustment, although it is acceptable that the brightness of the LEDs be reduced slightly by the addition of more LEDs in the circuit.
So I've done LED drivers before in design, but in terms of building them I have only ever used display drivers that handle a single LED per driver and have a common return back to the chip. I have made designs for buck drivers, but never built one yet. I do know that the best way to drive LEDs is in series, and that driving them in parallel has several drawbacks. I also know that a constant current buck converter will not be a safe option for this configuration because the load will not be balanced with the LEDs wired in parallel.
Given these design criteria, I don't know how to drive them.
The best theory I have at this time is to PWM a P-FET on the high side, low pass filter, and have individual current limit resistors at each LED. This does not seem like the best way to do it though.
Any help is greatly appreciated,
Mike