Sometimes the LED may end up damaged during testing without the engineer becoming aware. Special attention must be paid to not overdrive the LED during the testing (for more details on LED testing, please read below).
The testing engineer should also be aware of Electrical Stress Damage (electrical overstress) during the testing.
- Electrical Overstress (EOS) :
EOS threats are mainly due to poor handling and/or test fixture design;
The most severe transient conditions on power and data lines are surges caused by nearby lightning strikes and equipment switching.
- Electrostatic Discharge (ESD) : ESD damage can occur in several ways, including
A charged object (including a person) contacting an ESD-sensitive (ESDS) item;
A charged ESDS device contacting ground or another conductive object at a different potential;
An ESDS device is grounded while exposed to an electrostatic field.
LED manufacturers recommend guidance on preventing and managing ESD/EOS threats. The IEC 61340-5 and ANSI/ESD S20.20 standards provide this guidance on preventing EOS and ESD damage while LED components are being assembled into a system.
- Reverse Polarization
Most LEDs produce light in forward bias and are not generally designed for reverse bias operation. LEDs consist of a p-n junction, and if a high voltage surge goes through the device in the reverse direction the junction can be destroyed due to the excessive current.
LED manufacturers recommend that zener diodes are used for testing your system prior to installation of LEDs.