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?