LM334 Constant Current Source Test - Part 4/5 (High Current Circuit Design)

Introduction

I put the LM334 high current circuit and instead just test the one series, no CCS case with RGWYW LEDs, with and without heat sink.

I found the results disappointing: The CCS cicrcuit does not seem to perform better than the 24R single resistor circuit.  I also tried different values for the bias resistor, from 560R to 3k. I found that smaller the resistor, the larg the LED current in the ranch of 78mA (for 1k) to 56mA (for 3k).

I also don't know how to better control the LED current beside change the values of Rset and R1.  So I need to google again for more design ideas.

.END

Comments

Post a Comment

Popular posts from this blog

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

Image
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.
Read more