Current sense and efficient LED driver?

On a sunny day (Tue, 11 Feb 2014 10:22:24 -0800) it happened Daniel Pitts wrote in :

Of course not, but neither does Jimmy boy's. You need an indcutor for that as I pointed out before, as many others did. As I (and I think you too) have no clue what you are trying to do, it is hard to tell if any switching circuit would accomplish something that I could design even when half asleep, in a few microseconds. :-)

I know exactly what I'm trying to do, but I doubt you could help me. You're too busy trying to feel smugly superior. Good bye.

you already got a couple of answers before the mud slinging start (standard procedure here)

and the point still stands, if you want higher efficiency you need and inductor

I'm guessing from what you wrote that you want to drive the LEDs in some sort of matrix then it gets trickier

you need to give us some more info, what color LEDs?, how many?, in a matrix? scanned how fast?, what supply voltage?

-Lasse

I'm more interested in the theory, and I've got a solution that works without all this "optimal" stuff.

My project is: 8x8x3 matrix, RGB. Common anode per row for all colors (8 anodes signals). Common cathode for each column/color (24 cathode signals).

I've been using 5v supply, but I could probably get away with less .

960hz refresh (60hz per "frame", with up to 16 pulses each). It scans each row individually, so each "pulse" happens at 7680hz. Brightness is controlled with "duty cycle", so an LED is on for the number of pulses that corresponds to its brightness level.

Design constraints are that the control circuitry must fit on a 2-layer board that is

;)

I think the simplest that would fit on such a small board would be to add a switching supply of say 3V for the red and green led, the drop-out of the TLC5916 looks it is around 1V so the Blue is near minimum at 5V already

-Lasse

On a sunny day (Tue, 11 Feb 2014 15:01:40 -0800) it happened Daniel Pitts wrote in :

Then why ask here?

That is your problem, you would noy be able to pay the fee anyways.

Bit touchy are't we? :-)

You have no idea of my financial situation, and to imply you do proves what I thought about you.

Not really.

Daniel, You're discovering who are the pompous assholes resident here and pretending to expertise.

If you want to contact me privately, I'd be happy to give you some pointers... I have substantial experience in high accuracy LED driving schemes, as in...

I doubt that you need something as involved as that ;-) ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142   Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

Can't escape them anywhere ;-) Sometimes its fun to taunt them, but mostly I just ignore them. The only annoying part is when my thread gets hijacked by one of them, and someone else who thinks they can influence their behavior. Eg. Troll feeders are almost as bad as trolls.

I appreciate the offer immensely. It was your work that inspired my question actually.

Definitely not. This is just for me to have a little trinket to play with. Actually, I've already got the trinket on a protoboard. My PCBs are being shipped now, for a more permanent form.

A lot of what I do next depends on how these turn out. I may move on to my next (completely unrelated) project. Or I may decide to turn this into a wearable. I don't know yet.

Mentoring privately looks like what I'll have to resort to... that PAL with the HUB syndrome constantly sniffing my crotch is as irritating as the neighbor's dog >:-} ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142   Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

But the dog most likely has more friends it can go out on the town with and sniff, piss and shit anywhere they'd like!

Jamie

On a sunny day (Thu, 13 Feb 2014 21:04:43 -0500) it happened "Maynard A. Philbrook Jr." wrote in :

Poor Jimmy boy, trying to sell himself as electronics designer, what do we have oscillating audio amps, cannot make a LT spice circuit diagram, falsifying original designs he claimed worked OK by constantly changing them, incapable of admitting being wrong, using dirty language against real designers like J.L. and others who point out Jimmy's errors. polluting Usenet with ever the same alcoholic adds as sig, pushing guns on Usenet, Even taken in consideration the final stages of Alzheimer's that does not justify posting here. The saddest part is that if he starts 'advising' others offline, for example via email, then those will experience all the problems that at least here get pointed out, and without our help will those people will get stuck or spend large amounts of time and money for nothing. And _that_, is the reality of it. And he is a patent troll too, patenting the more than obvious, and probably even the wrong and useless. See Jimmy, no need for a personal attack, your work is enough of a target, :-)