a thing that one miss in most of these introductory notes is the fact that in some applications one would also like to control the maximum voltage on a LED string and not only the led string current... not all devices on the market has this function. This is for example when you have different devices on a control panel such as displays and luminating LEDS on control buttons and knobs. In these applications controlling the voltage reduces the number of different types of LED driver devices required.
Hmmm, series vs. parallel connections of WLEDs?
This seems very timely in this holiday season when many non-engineers learn about series vs. parallel circuits the hard way as they debug strings of Christmas lights that don't fully light!
Students might like this; comparing several engineering solutions for the same problem. Sure, it is a little biased in favour of Micrel's product, but hey, it is an infomercial, after all. I agree about the charge pump's unavoidable inefficiency (peak currents are huge if the switches have low R(on)); but I don't think an inductive buck/boost circuit can be dismissed quite so easily, especially if it extends battery life for the whole product.
Here's three ideas for comment:
- I foresee the next generation switchers using tiny ultra-high-frequency SiC devices switching 'free' inductors formed from PCB traces.
- Staying with analog, maybe it's about time a manufacturer made a LED with a self-regulating characteristic.
- Could LEDs be made tough enough to work as switcher diodes, thus making a self-illuminating regulator?