On Mon, 26 Jan 2009 15:45:37 +0530, "pimpom"
put finger to keyboard and composed:

Franc Zabkar wrote:
On Mon, 26 Jan 2009 00:21:34 +0530, "pimpom"

put finger to keyboard and composed:

Does anyone have specific information about the protection
device
at the power supply inputs of hard disks?

I assume that it's a zener diode or something similar in
action
such as an IC that acts like a precision zener diode.

Is it a transient voltage suppression diode?
http://en.wikipedia.org/wiki/Transie...pression_diode

Could be. In fact, I mentioned that in my second post. What I
find surprising and frustrating is that I have not been able to
find any data on the BUX C*** series.

This forum discussion is about TVS devices in hard drives:
http://forum.hddguru.com/seagate-bar...ide-t9356.html

The above discussion refers to this photo of a Seagate HDD with two
TVS devices made by ON Semiconductor:
http://forum.hddguru.com/download/file.php?id=562

The parts have the following markings:

ON logo QE
R617

ON logo 620
LEM .

I can't find exactly the same parts in ON's datasheets, but here are a
few similar looking devices:

Unidirectional Zener TVS 13V 600W (marking = LEN):
http://www.onsemi.com/pub/Collateral/NSB13AN-D.PDF

Zener Transient Voltage Suppressor 12V 600W (marking = LEK):
http://www.onsemi.com/pub/Collateral/NSB12A-D.PDF

400W Peak Power Zener Transient Voltage Suppressor 5V (marking = QA):
http://www.onsemi.com/pub/Collateral/NSA5.0A-D.PDF

600 Watt Peak Power Zener Transient Voltage Suppressor 5V (marking =
6QE):
http://www.onsemi.com/pub/Collateral/NS6A5.0A-D.PDF

Here is a Vishay patent that discusses TVS devices with particular
reference to their application in hard drives:
http://www.freepatentsonline.com/WO2008002421.html

- Franc Zabkar
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