What does a "self-ballasted" LED mean ?

[daku...@gmail.com]

Could some electronics guru pleas explain what
a "self-ballasted" LED lamp mean ? I have seen
LED lamps, running off the AC line, and powered
by a simple small 5V 1 Amp SMPS, but what exactly
does a self-ballasted LED lamp mean ?

[Don Y]

built in current limit???

[Jasen Betts]

It depends on the context.


possibly it has a resistor inbuilt for operation at some specified
voltage.

--
umop apisdn

[Martin Brown]

In series with something that approximates a constant current source for
some reasonable range of applied input voltages. Could be as simple as a
crude ballast resistor or a semiconductor based device.

A bare LED has a rather rapid increase in current through it once it
starts to glow with a slightly higher applied voltage leading vastly
increased current and then total destruction if you go too high.

You can do some cute physics experiements plotting V-I curves for LEDs.
eg.

http://www.phys.uconn.edu/~hamilton/phys258/N/led.pdf

Expect some LEDs to be destroyed in this practical.

--
Regards,
Martin Brown

[Piotr Wyderski]

Martin Brown wrote:

> A bare LED has a rather rapid increase in current

Like any other PN junction: I(U) is exponential.

Best regards, Piotr

[Maynard A. Philbrook Jr.]

In article <227fa5bf-db57-412f...@googlegroups.com>,
daku...@gmail.com says...

it means it has the require components inside to
accommodate a direct connection to a commonly known
source.

Even with that, you still need to ensure you get the
correct one that matches the voltage you are attaching
it to.

Jamie

[daku...@gmail.com]

Thanks. Your explanation seems to be the most likely one.
We were looking at specifications for certification of
AC wall socket compatible LED lamp in as Asian country.

[Robert Baer]

That term is also used for dual transistors; means "resistor(s) added".