Tagged Questions

0
votes
1answer
26 views

R-EXT connection on the STP16CP05MTR LED sink driver

I'm planning to use a STP16CP05MTR LED sink driver to drive some LEDs in a matrix. The STP16CP05MTR supports constant current by the use of an external resistor ...
1
vote
1answer
41 views

TLC5926 With No Load

I've read here that running the TLC5940 with no load can cause some issues with it drawing excessive power. The TLC5926 is a constant current driver rather than a PWM driver. It seems to me that since ...
3
votes
2answers
371 views

Efficient constant-current regulator for 700ma LEDs

I'm building a lamp with twelve 3x700ma RGB LEDs in it, that need to be individually PWM controlled (100-200Hz), so they can display different colours from each LED. To do this then, I think I need a ...
2
votes
1answer
542 views

Constant current circuit with transistors/MOSFETs design comparison

There are a few designs out there for constant current devices, but most of them use a certain chip. I was looking for a way to build my own constant current supply from parts that I have available. ...
5
votes
2answers
76 views

BCR402R - what is the purpose of Rext in this LED driver?

I'd like to know what is(are) the purpose(s) of Rext in the BCR402R LE driver circuit. The BCR402R is a 20 mA constant current LED driver. The application circuit (see below) shows an external ...
4
votes
2answers
478 views

How to dim an LED with constant current supply?

I have a power RGB led with 350 mA max per color. If I get 3x 300-350 mA constant power supplies will I be able to dim each individual color from 0 to 100% power with Arduino (with NPN transistors)? ...
5
votes
2answers
444 views

Using a TLC5940 to control LEDs with different forward voltages

I am trying to build an LED matrix (64x32) of RGB LEDs using a TLC5940 current sink LED driver. The forward voltages of the LED components for each RGB LED are: R: 1.8V G: 2.8V B: 2.8V The driver ...
1
vote
1answer
375 views

PWM LED dimming via constant current source

I have this idea to dimm LEDs and I'd like to get some opinions if it's feasible. Q1 and M1 form a constant current source, Q1 ensures a 0.7V drop across R2 by pulling M1 gate to ground. Q2 gets a ...
4
votes
2answers
320 views

Powering RGB LED's and using a PWM chip; series or parallel?

I'm working on a hobby project where I will be using an Arduino board and a TLC 5940 to control 5 different groups of RGB LED's. The number of LED's in any particular group will not necessarily match ...
1
vote
2answers
372 views

Low loss current sink

I'm working on a battery powered device that has 4 individual LED drivers. The output from the LEDs are controlled with separate PWM signals from a small MCU. This has to be low cost, and a low cost ...
5
votes
4answers
2k views

Adjustable linear led driver? Linear, not PWM

I'm working on a product that requires an led to output currents varrying from 0mA to 350mA and as many possible levels in between (~1000 would be sufficient I suppose). I CANT output a PWM signal to ...
1
vote
4answers
509 views

Improving this current regulated LED driver circuit

In this here circuit the function generators at the left represent the digital output pins from a microcontroller. I happen to be using an Arduino Uno for that purpose at the moment and the relevant ...