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.

7 segment LED with integrated zener diode .

Status
Not open for further replies.

xandeyes

Junior Member level 1
Joined
Nov 22, 2013
Messages
17
Helped
1
Reputation
2
Reaction score
1
Trophy points
3
Activity points
138
Hi all,
I have requirement for a display PCBA, It has some 7-seg LEDs display (used for home appliance).
I met a problem: after a certain time, one or several segments were broken and no light. (error rate about 0.5%)
To solve this trouble, our supplier (an IDH) who designed my PCBA said he must design the new 7-seg LED with integrated Zener diode to avoid damage by EM environment.
To integrated zener, he have to use a custom led by open a new mold for LED.

I tried to find some led built-in zener on internet, no many LED use this solution. So, do you think he said correct or not ?

Thanks.
 

KlausST

Super Moderator
Staff member
Joined
Apr 17, 2014
Messages
19,722
Helped
4,343
Reputation
8,695
Reaction score
4,304
Trophy points
1,393
Activity points
130,544
Hi,

I see no reason, why the zener can't be external.

I don't think EM (HF) is a problem, I rather think it's overvoltage, overcurrent or overheat.
But LEDs are rather robust, but they don't like reverse voltage.

Please show photos of display, PCB, wiring, mounting...

Klaus
 

betwixt

Super Moderator
Staff member
Joined
Jul 4, 2009
Messages
14,927
Helped
4,874
Reputation
9,766
Reaction score
4,662
Trophy points
1,393
Location
Aberdyfi, West Wales, UK
Activity points
126,983
LEDs are already constant voltage devices so there is no point in placing a Zener across them. If reverse voltage may be an issue, a normal diode will work just as well. As Klaus stated, the problem isn't likely to be over voltage (where a Zener might help) but over current which is a design issue a diode can't fix.

Brian.
 

xandeyes

Junior Member level 1
Joined
Nov 22, 2013
Messages
17
Helped
1
Reputation
2
Reaction score
1
Trophy points
3
Activity points
138
Thank Klaus and Betwixt,
Your information is very helpful. I check with my partner on the design to solve my problem.

Regards.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top