Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Charlieplexing & LED leakage

Status
Not open for further replies.

faisal78

Member level 3
Joined
Aug 27, 2004
Messages
62
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Activity points
592
Hello
I am designing a charlieplexing LED drive scheme using an Arduino board.
Schematic 3.jpg
Connection are something similar to the above.

LED1/2/3/4 are all RED LEDs with a Vf of ~2v.
LED 5/6 are BLUE LEDs with a VF of 3.6v.
All LED source is driven from 5V supply.

In theory, when I am driving LED5 to be turned ON, there should also be a leakage path through LED1/3 because the Vf of the RED LEDs are so low.
Can anybody confirm this?
FOr some odd reason, I am unable to replicate this symptom on my board and was working if that my setup/configuration was wrong.
Any help/clues?

Thanks in advance.
 

Hello
I am designing a charlieplexing LED drive scheme using an Arduino board.
View attachment 105751
Connection are something similar to the above.

LED1/2/3/4 are all RED LEDs with a Vf of ~2v.
LED 5/6 are BLUE LEDs with a VF of 3.6v.
All LED source is driven from 5V supply.

In theory, when I am driving LED5 to be turned ON, there should also be a leakage path through LED1/3 because the Vf of the RED LEDs are so low.
Can anybody confirm this?
FOr some odd reason, I am unable to replicate this symptom on my board and was working if that my setup/configuration was wrong.
Any help/clues?

Thanks in advance.


Hello, another great example of the possible leakage issue can also be seen in the below application, which I have taken from
https://fritzing.org/projects/charlieplex-snowfallshooting-star-20-leds

Same scenario, when trying to intentionally turn on LED04, the anode (green) would be ~5v, and cathode (blue) would be ~ground.
There is a possibility of a leakage path via LED03 and LED10 which I had marked out the path on the diagram.

Capture_leak.JPG
 

LED1/2/3/4 are all RED LEDs with a Vf of ~2v.
LED 5/6 are BLUE LEDs with a VF of 3.6v.
The worst of all possible combinations, can't work without unwanted lighting of red LEDs.
 

The worst of all possible combinations, can't work without unwanted lighting of red LEDs.

Hmmm, is there really no solution to Charlieplexing a RGB LED from a single power source?
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top