Nichia STS-DA1-0043A
<Cat.No.071228>
(3) Static Electricity
· Static electricity or surge voltage damages the LEDs.
It is recommended that a wrist band or an anti-electrostatic glove be used when handling the LEDs.
· All devices, equipment and machinery must be properly grounded. It is recommended that precautions
be taken against surge voltage to the equipment that mounts the LEDs.
· When inspecting the final products in which LEDs were assembled, it is recommended to check
whether the assembled LEDs are damaged by static electricity or not.
It is easy to find
static-damaged LEDs by a light-on test or a VF test at a lower current (below 1mA is recommended).
· Damaged LEDs will show some unusual characteristics such as the forward voltage becomes lower,
or the LEDs do not light at the low current.
Criteria : (VF > 2.0V at IF=0.5mA)
(4) Application Design Considerations
· In designing a circuit, the current through each LED must not exceed its absolute maximum rating.
It is recommended to use Circuit B which regulates the current flowing through each LED.
In the meanwhile, when driving LEDs with a constant voltage in Circuit A, the current through
the LEDs may vary due to the variation in forward voltage (VF) of the LEDs. In the worst case,
some LED may be subjected to stresses in excess of the absolute maximum rating.
(B)
(A)
· Thermal design of the end product is of paramount importance.
Please consider the heat generation
of the LED when making the system design. The coefficient of temperature increase per input
electric power is affected by the thermal resistance of the circuit board and density of LED placement
on the board, as well as other components. It is necessary to avoid intense heat generation and operate
within the maximum ratings given in this specification.
· Please determine the operating current with consideration of the ambient temperature local to the LED
and refer to the plot of Ambient temperature vs. Allowable Forward Current on CHARACTERISTICS
in this specifications. Please also take measures to remove heat from the area near the LED (heat sink)
to improve the operational characteristics of the LED.
· The equation 1 indicates correlation between Tj and Ta, and the equation 2 indicates correlation
between Tj and Tc.
Tj=Ta + RjaꢂW
1
Tj=Tc + RjcꢂW
2
ꢀTj = Dice Temperature : °C, Ta = Ambient Temperature : °C,
Tc = Die Heat sink Temperature : °C,
Rja = Heat resistance from Dice to Ambient temperature : °C /W,
Rjc = Heat resistance from Dice to Tc measuring point ≒ 10°C /W,
W = Inputting Power (IF ꢁ VF) : W
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