High Current Constant Current Source For RGB Power LEDS - Part 1 (Preliminary Design)

Introduction

I found LM334  CCS's performance in high current mode not very satisfactory for current higher than 100mA.  So I am thinking of exploring other circuit designs.

I quickly read the follow articles to get a rough idea of different CCC circuit designs.

[1]  Active Transistor Constant Current Source - electronics-notes.com

[2]  The Basic MOSFET Constant-Current Source June 06, 2016 by Robert Keim - aac

[3]  Current Mirror BJTs - aac

[4]  Simple constant-current driver - lednique

[5]  Simple variable current source for approx 2A, constant load - EESE, 2017jun06

[6]  Current Limiting - Wikpedia 

[7]  Current Source - Wikipedia


After comparing and contrasting all these designs, weighing pros an cons, I am thinking of exploring the following circuit as described below:

1. One power MOSFET 

2. One DAC

3. One current sensing amplifier.

/ to continue, ... 








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LM334 Constant Current Source Test - Part 5/5 (LM334 Theory, Pracice, and DIY)

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Introduction The performance of LM334 High Current circuit is poor. I think the main reason is that the PNP BJT current amplification is difficult to design, because  (1) The transistor needs to be in saturation mode, but static current gain is not well defined, and therefore bias current also not easy to specify. (2) I could not any design/application notes on this high current circuit. However, I found the following two references explaing very well the theory behind the LM334 device.  I am thinking of DIYing a similar CCS using power MOSFET, to achive high current. Next post will not be talking on LM334.  In other words.  This is the last post of LM334.
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