OSRAM has quite good datasheet for this kind of things. However
a duty cycle of 8% and 70ms pulse time will not increase the
pulsing current above the DC forward current by much. I will
guess in your application, the LED can not pulse higher than
20mA without causing derating.

Normally we use high pulse current capability RED/InfraRed
LEDs for our applications. OSRAM is a good source for this
kind of applications and so far it has the best datasheets,
better than Agilent/Vishay/Stanley/...

Eg: SFH464 Red Led Emitter, Datasheet from OSRAM
DC forward current: 50mA

Permissible Pulse Handling
Capability IF =3D f (?), TA =3D 25 =B0C,
duty cycle D =3D parameter

Pulsing current at D=3D1% using 10us pulse (100us period): 400mA max
Pulsing current at D=3D10% using 10us pulse (100us period): 850mA max
Pulsing current at D=3D10% using 100us pulse (1ms period): 200mA max
Pulsing current at D10% using 1ms pulse (10ms period): 85mA max
Pulsing current at D=3D10% using 10ms pulse (100ms period): 72mA max

For some of the LEDs, they have a parameter called surge current:
Eg: LST676 PLCC2 SMD LED
DC forward current: 30mA
Surge current: 1A
(Surge current: t ? 10 =B5s, D =3D 0.005, TA=3D25=B0C)

Regards,
Xiaofan

-----Original Message-----
From: piclist-bounces@mit.edu=20
Sent: Friday, October 21, 2005 8:04 AM
To: piclist@mit.edu
Subject: [EE] Pulsing LEDs

any pointers on pulse driving LEDs ?
Assuming a standard 10mA  5mm LED, what sort of repetition frequency and =
max

current would be suitable for a led that has a duty cycle of 8%, (
illuminated=20
for about 0.07 seconds each second ) are there any manufacturers guidelin=
es=20
about this?
--=20

--=20
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