AB188 LUXEON Automotive LEDs Application Brief 20170530 ©2017 Lumileds Holding B.V. All rights reserved.

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LEDs may not have an integrated ESD protection. LEDs with integrated, unidirectional ESD protection, when operated in

reverse direction, will have a current path and will be destroyed by overcurrent.

• Prevent negative potential from reaching LEDs

– UseofRectifier(Blocking)Diode(seeFigure5)orBlockingFET,intheinputcircuitry,preventsnegativepotential

from being applied to, and potentially damaging, the LEDs

• Provide Circuitry to negate requirement for input polarity

– RectifierBridge,etc.

Addingcircuitrytonegatepolaritycanbeexpensiveandcausepowerlosses,whichmaynotbejustifiedbythelimited

number of connect/disconnect cycles involved. Methods of driver design shall prevent application of a reverse voltage to

the LED (i.e. Poka Yoke or keyed connectors).

3. ESD Guidelines

The likelihood of electrical stress in an LED application can be reduced by taking the following recommendations into

account during the design of the application:

• Maintain proper spacing between signal traces and board edge in an MCPCB/IMS board and proper distance between

signal traces and any grounded surface on the PCB (per IPC-2221B)

• Make use of guard traces/surfaces at edge of PCB, connected to ground, stitching together ground traces on top and

bottom layer (see Figure 6)

• Consider grounding the heatsink, if practical

• WhereverfloatingelectricalconductivematerialsarepotentiallyexposedtoanESDimpact,sensitivesignaltracesin

close proximity need additional protection, for example, by adding large creepage distances or a guard ring. A guard

ring (trace) is a barrier connected to a certain potential (e.g. ground), which can protect the sensitive trace signal from

ESD event

• Add bypass capacitors and discharge protection capacitors whenever possible

• Use common ESD protection methods during manufacturing and installation of LED lamps (e.g. ankle-straps, wrist-

straps,ESDsafeshoes,conductiveworkmats,conductiveflooring,iongenerators,etc.)

• No unconnected metal on PCB to avoid spreading ESD event into the circuit

• Design the product and the process such that direct contact, with ESD sensitive component, is avoided during

assembly

• Most Lumileds high power automotive LED packages feature an integrated TVS protection diode, providing ESD

protectionforhandlingthecomponenttoacertainlevelaccordingtoproductspecification.IfahigherlevelofESD

protection for rough environments (e.g. according to ISO 10605) is needed, additional external unidirectional TVS

devices are necessary, connected parallel to the LED

• Testing performed using Human Body Model (HBM) (see Figure 3)

• Damage can present itself as shown in Figure 4