HSMA-A10X データシートの表示（PDF） - Broadcom Corporation

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HSMA-A10X

PLCC-2, Surface Mount LED Indicator

Broadcom Corporation 

HSMx-A10x-xxxxx Data Sheet

 If the LED is intended to be used in harsh or outdoor

environment, protect the LED against damages caused

by rain water, water, dust, oil, corrosive gases, external

mechanical stresses, and so on.

Thermal Management

The optical, electrical, and reliability characteristics of the

LED are affected by temperature. Keep the junction

temperature (TJ) of the LED below the allowable limit at all

times. TJ can be calculated as follows:

TJ = TA + RθJ-A x IF x VFmax

where;

TA = ambient temperature (°C)

RθJ-A = thermal resistance from LED junction to ambient

(°C/W)

IF = forward current (A)

VFmax = maximum forward voltage (V)

The complication of using this formula lies in TA and RθJ-A.

Actual TA is sometimes subjective and hard to determine.

RθJ-A varies from system to system depending on design

and is usually not known.

Another way of calculating TJ is by using the solder point

temperature, TS as follows:

TJ = TS + RθJ-S x IF x VFmax

where;

TS = LED solder point temperature as shown in the

following figure (°C)

RθJ-S = thermal resistance from junction to solder point

(°C/W)

IF = forward current (A)

VFmax = maximum forward voltage (V)

Figure 16: Solder Point Temperatures on PCB

Package mark

PLCC-2, Surface Mount LED Indicator

TS can be easily measured by mounting a thermocouple on

the soldering joint as shown in preceding figure, while RθJ-S

is provided in the data sheet. Verify the TS of the LED in the

final product to ensure that the LEDs are operating within all

maximum ratings stated in the data sheet.

Eye Safety Precautions

LEDs may pose optical hazards when in operation. Do not

look directly at operating LEDs because it might be harmful

to the eyes. For safety reasons, use appropriate shielding or

personal protective equipment.

Ts point

Broadcom

AV02-0198EN

16

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