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'[EE]: 7912/7905'
2001\03\08@192642 by Andy N1YEW

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whats the pinout of a 7905 and 7912? They are negative voltage regulators.

I think they are like this

looking at front(not tabbed side)

Input   Gnd   Output

Andy N1YEW

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2001\03\08@230901 by Anand Dhuru

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face
No Andy, thats how the positive regulators (78XX) are pinned; the 79XX parts
are Gnd-Inp-Out

Regards,

Anand

{Original Message removed}

2001\03\09@030551 by Sean H. Breheny

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I've always wondered if this was so the 79xx series parts wouldn't be
damaged if you put them into a 78xx series circuit (the input would be
negative wrt the GND terminal, and the regulator would just try to keep the
output at V+ minus the rated voltage).

Is this why? Any thoughts?

Sean

At 09:41 AM 3/9/01 +0530, Anand Dhuru wrote:
>No Andy, thats how the positive regulators (78XX) are pinned; the 79XX parts
>are Gnd-Inp-Out
>
>Regards,
>
>Anand
>
>{Original Message removed}

2001\03\09@041224 by Vasile Surducan

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That's because there is an internal protection diode between in and out.
Vasile

On Fri, 9 Mar 2001, Sean H. Breheny wrote:

{Quote hidden}

> >{Original Message removed}

2001\03\09@041850 by Spehro Pefhany

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At 03:06 AM 3/9/01 -0500, you wrote:
>I've always wondered if this was so the 79xx series parts wouldn't be
>damaged if you put them into a 78xx series circuit (the input would be
>negative wrt the GND terminal, and the regulator would just try to keep the
>output at V+ minus the rated voltage).
>
>Is this why? Any thoughts?

The die is bonded to the heatsink tab, which should be the most
*negative* point.  That's ground on the 78xx and input on the 78xx.

Best regards,


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2001\03\09@042055 by Spehro Pefhany

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At 03:06 AM 3/9/01 -0500, you wrote:
*negative* point.  That's ground on the 78xx and input on the 78xx.
                                                             ^^^^
<cough> 79xx

Best regards,


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2001\03\09@075529 by Alan B. Pearce

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>Input   Gnd   Output

definitely not. One end is ground. These are not a 7800 series device with pnp
transistors in place of npn. It still uses npn transistors inside and the pin
functions are adjusted to suit. It does mean you have to insulate the tab if
mounting it to a grounded heatsink.

I cannot tell you the pinout off hand, but I know the above from my first use of
7900 series devices.

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2001\03\09@082301 by Randy Glenn

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Don't know for sure, but you could probably find a datasheet at
http://www.national.com

- -Randy Glenn

This coming from the guy with a system tray 10 icons wide... by 2
tall... yes, I am insane ;)
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- {Original Message removed}

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