Wed Apr 19 22:55:01 EDT 2017
Pulsed LED power supply
What if it were simpler to create a pulsed supply and use it to create
brightness profile, than to gate a constant supply with a mosfet.
Googling, some more about current vs. brightness curves - not what I wanted.
It seems better to go for switched current sources like:
The 15uH power inductor seems expensive comparted to rest of circuit.
This is likely why using a series resistor is still a common thing.
The other LED light I have uses R-L-L-L series, equally distributed.
Doing the same for a 10W LED (1A, 9V) with 3V resistor drop would
require a 3Ohm, 3Watt resistor. That is a lot.
Ajna light material is pretty woo-woo. Looking for some clearer material, found this:
Dr.med. Dipl.-Psych. Dirk Proeckl
Hmm not less wonky.
current mode converters
- in a current-mode buck converter, why is there a capacitor?
it filters the ripple current. for LED driver, ripple might not be
I found at least one circuit that doesn't have the cap, and uses a
switch to ground to charge the inductor.
Circuit could be calibrated to run in feedforward PWM only.
- how to pick an inductor?
higher frequencies allow for smaller inductors, but create more
switching losses. where is the optimum?