LPC826 - Case Pisitive or Negative?

[adambowker]

EDIT: Title should say "Positive," not "Pisitive," and I don't know how to change it

Hi all -

Jmillerdoc has recently been kind enough to send me an LPC826 diode and 12mm module for free to help with my first build (thanks again man ).

I have decided on the SurvivalLasers C6 host and their driver set at something like 465mA.

The only problem I have is that I don't know if the LPC826 is case-positive or case-negative. I have been told it is case positive, meaning I need an anodized heatsink, but I was also told it was case negative and not to get an anodized one. Can someone clarify it for me? I don't want to wire it the wrong way and blow my only diode if I can prevent it.

Thanks in advance, everyone!
Adam

 

[NKO29]

 

[adambowker]

Thanks - so it IS case negative? If so I won't need an anodized heatsink, right?

Adam

 

[Seoul_lasers]

Thanks - so it IS case negative? If so I won't need an anodized heatsink, right?

Adam

errr.... ummmm....

I am not sure by your definition of what Anodized means? However,
Anodizing is a way of protecting or coating metals &
It's got nothing to do with polarity.

:thinking::thinking::thinking::thinking:


You can use virtually any metal to use as a way of housing a laser diode, be it Copper, brass, Silver or even gold for that matter...
just as long as it can conduct heat well.
:can: :can: :can: :can:

 

[adambowker]

errr.... ummmm....

I am not sure by your definition of what Anodized means? However,
Anodizing is a way of protecting or coating metals &
It's got nothing to do with polarity.

:thinking::thinking::thinking::thinking:


You can use virtually any metal to use as a way of housing a laser diode, be it Copper, brass, Silver or even gold for that matter...
just as long as it can conduct heat well.
:can: :can: :can: :can:

I know anodized has nothing to do with polarity.

I was talking about using the anodized heatsink to isolate the diode from the host if it had been case positive; if it's anodized it won't conduct electricity.
(At least that's what I've been told I need to do with case-positive in the past. Here's a picture I found on the forums showing the diode isolated from the host in case-positive:

)

 

[123splat]

NO!! You do NOT want the Anodized sink.
Seoul, et.al., Anodizing creates an INSOLATING film on the material. If one was to use an anodized heatsink, in a case where the sink is used as part of the conducting path, they would have to provide a conducting path around (use the diode's case pin in this incidence), or through (remove the anodizing), the sink. Anodized heatsink is a waste of time and effort.

 

[adambowker]

NO!! You do NOT want the Anodized sink.
Seoul, et.al., Anodizing creates an INSOLATING film on the material. If one was to use an anodized heatsink, in a case where the sink is used as part of the conducting path, they would have to provide a conducting path around (use the diode's case pin in this incidence), or through (remove the anodizing), the sink. Anodized heatsink is a waste of time and effort.

Thanks! However, if the diode was case positive, you WOULD need an anodized heatsink... right?

And, just to confirm again... the LPC826 is case-negative. Correct?

 

[Seoul_lasers]

I know anodized has nothing to do with polarity.

I was talking about using the anodized heatsink to isolate the diode from the host if it had been case positive; if it's anodized it won't conduct electricity.
(At least that's what I've been told I need to do with case-positive in the past. Here's a picture I found on the forums showing the diode isolated from the host in case-positive:

)

I see what you're saying now. You had me a little confused.
The word you were looking for was electrically isolating.

 

[adambowker]

I see what you're saying now. You had me a little confused.
The word you were looking for was electrically isolating.

Ah - sorry about that

And can you confirm that the LPC826 is in fact a case-negative diode?

 

[KRNAZNBOY]

Yes the LPC is a case negative diode. This is great for all conventional drivers as they are continuous GND. As long as you use a x-boost/drive, or flexdrive, microboost, etc you will be fine with an un-anodized heat sink.

If you go with say an AMC7135 Driver, which is continuous positive, you will need a case positive diode or an anodized heatsink



Hope this helps!

-Matt

 

[adambowker]

Yes the LPC is a case negative diode. This is great for all conventional drivers as they are continuous GND. As long as you use a x-boost/drive, or flexdrive, microboost, etc you will be fine with an un-anodized heat sink.

If you go with say an AMC7135 Driver, which is continuous positive, you will need a case positive diode or an anodized heatsink



Hope this helps!

-Matt

Thanks Matt! I am most likely going to order this SurvivalLasers buck driver at 530mA - that'll work right?

EDIT: Forgot to say that I'm getting the unanodized aluminum heatsink as well

 

[IsaacT]

Buck Drivers should be fine. And a flexdrive would be okay. But you need to not use a Microboost on any red diodes. Just a rule of thumb that you don't boost reds. Their forward voltage is low enough that they don't need it. If I remember correctly of course.

 

[Seoul_lasers]

Buck Drivers should be fine. And a flexdrive would be okay. But you need to not use a Microboost on any red diodes. Just a rule of thumb that you don't boost reds. Their forward voltage is low enough that they don't need it. If I remember correctly of course.

Red LDs typically have a forward voltage of about ~ 3.2-3.5v ... typically never exceeding 3.5v.

Correct you are!

 

[DTR]

Thanks! However, if the diode was case positive, you WOULD need an anodized heatsink... right?

In that case you would want a driver that regulates via the negative side and can run with a continuous positive. Like a IR driver used in most green DPSS pointers.

 

[Jmillerdoc]

You can still use an anodized heat sink with a case negative diode. Instead of using the heat sink as part of the current path you just need to connect the diode directly to your driver. Just use the negative pin wired directly to the driver's LD - output. If you already bought the anodized heat sink this is much easier to do than trying to remove the anodizing to make an electrical path to the diode.

 

[Jmillerdoc]

Since we've got that picture of the diode up top and I've always wondered what the "not used" pin is for.....what is the "not used" pin not used for? Surely it has a purpose? Why would a manufacturer go through the trouble of putting it there for no reason? The only thing I can think of is they just had a few million diode bodies with these pins laying around that were intended for another use and they decided to make something else with them that didn't require the pin. Someone here know why we have this extra pain?