# What does a "self-ballasted" LED mean ?

Started by November 19, 2014
```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 ?
```
```On 11/19/2014 8:40 PM, dakupoto@gmail.com wrote:
> 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 ?

built in current limit???

```
```On 2014-11-20, dakupoto@gmail.com <dakupoto@gmail.com> wrote:
> 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 ?

It depends on the context.

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

--
umop apisdn

```
```On 20/11/2014 03:40, dakupoto@gmail.com wrote:

> 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 ?

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
```
```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

```
```In article <227fa5bf-db57-412f-8fb7-a27513ada1c1@googlegroups.com>,
dakupoto@gmail.com says...
>
> 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 ?

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

```
```On Thursday, November 20, 2014 7:06:22 PM UTC-5, Maynard A. Philbrook Jr. wrote:
> dakupoto@gmail.com says...
> >
> > 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 ?
>
>  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

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.
```
```dakupoto@gmail.com wrote:
> 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 ?
That term is also used for dual transistors; means "resistor(s) added".

```