LM334 Constant Current Source Test - Part 2/5 (Large current (100 ~ 350mA) 1W RGBYW Power LED Lamp)

Introduction

Now I am using the LM334 high current circuit to test 1W RGBYW Power LED Lamps.

The circuit uses a PNP BJT, so I am reading the cs9012 datasheet to refresh my memory. 













So I wired up the LM334Z High Current Circuit to light up a 1W 350mA Ref power LED. 

I have no idea to use for R1 and C1. For the first trial I just use R1 = 1k and no C1. I found results looks OK.  

For Vcc = 5V, Current I through LED is 112mA, as show below.












Next is to test other colours, Y, B, W. If all RGBYW LEDs ha more or less same value of current, then I can conclude that this preliminary CCS big current test is OK.

I found the LED currents for the RGBYW LEDs are not equal, or nearly equal. The currents are:

R = 112mA

G = 95mA

B = 81mA

Y = 116mA

W = 85mA

Next is to try changing the value of the bais resister, and see if there is any improvement.

Anyway, the 1W white LED is bright enough to take a clear photo, as shown below.







Conclusion - Circuit seems not working, would troubleshoot later.

.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