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Rev2.0, Jan. 21, 2019

www.seoulsemicon.com

SWW0CS07S - WICOP-C

Precaution for Use

b. EOS (Electrical Over Stress)

Electrical Over-Stress (EOS) is defined as damage that may occur when an electronic device is

subjected to a current or voltage that is beyond the maximum specification limits of the device.

The effects from an EOS event can be noticed through product performance like:

- Changes to the performance of the LED package

(If the damage is around the bond pad area and since the package is completely encapsulated

the package may turn on but flicker show severe performance degradation.)

- Changes to the light output of the luminaire from component failure

- Components on the board not operating at determined drive power

Failure of performance from entire fixture due to changes in circuit voltage and current across total

circuit causing trickle down failures. It is impossible to predict the failure mode of every LED exposed

to electrical overstress as the failure modes have been investigated to vary, but there are some

common signs that will indicate an EOS event has occurred:

- Damaged may be noticed to the bond wires (appearing similar to a blown fuse)

- Damage to the bond pads located on the emission surface of the LED package

(shadowing can be noticed around the bond pads while viewing through a microscope)

- Anomalies noticed in the encapsulation and phosphor around the bond wires

- This damage usually appears due to the thermal stress produced during the EOS event

c. To help minimize the damage from an EOS event Seoul Semiconductor recommends utilizing:

- A surge protection circuit

- An appropriately rated over voltage protection device

- A current limiting device