In message , Dave Plowman
writes
In article ,
Major Scott wrote:
Take for example the brake/tail lights. These are often pulsed for
tail and on for brake. So what you said doesn't make sense.
Anything less than full voltage on (as for brake) will be lower heat.

LEDs are current, not voltage, driven.

When there's a series resistor, then you can think of them as voltage
driven.

Why would you have a 'series resistor' if they are pulse driven?

But in any case it is irrelevant. It's the current they are driven with
that matters - not the voltage.

Nothing is really only 'current driven'. It's more correct to say that
LEDs need to be driven from a power source which provides a fairly
well-defined current. Even when you drive them with pulsed current, the
amplitude of the pulses will be determined by the voltage producing the
pulses. At any instant, the power dissipated in the LED is simply the
product of the voltage across it (typically 2V, depending on the colour)
and the current flowing through it. When pulsed, the average power is
also determined by the mark-space ratio of the pulses.
--
Ian