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Leaky zener diodes

G

Gordon W

Jan 1, 1970
0
Hi
I've seen references in newsgroups to zener diodes that become leaky. Could
someone explain this for me please.

Gordon W
 
C

CFoley1064

Jan 1, 1970
0
Subject: Leaky zener diodes
From: "Gordon W" [email protected]
Date: 9/2/2004 5:32 PM Central Daylight Time
Message-id:
<[email protected]works.com.au>

Hi
I've seen references in newsgroups to zener diodes that become leaky. Could
someone explain this for me please.

Gordon W

A zener diode has a specified Vz (zener voltage) at a specified Iz (zener
current). Let's take a 1N4740A, which is guaranteed to have a Vz between 9.5V
and 10.5V if you apply 25mA across it.

It's also guaranteed that if you put only 7V across it, the current going
through the diode will be less than 10uA. This is called leakage current. A
leaky zener is one that has been damaged such that the reverse leakage current
at voltages below the zener test voltage is a lot higher than normal. It
frequently happens through momentary current surges that exceed what the xener
is capable of absorbing, which damages the diode.

Good luck
Chris
 
G

Gordon W

Jan 1, 1970
0
CFoley1064 said:
A zener diode has a specified Vz (zener voltage) at a specified Iz (zener
current). Let's take a 1N4740A, which is guaranteed to have a Vz between 9.5V
and 10.5V if you apply 25mA across it.

It's also guaranteed that if you put only 7V across it, the current going
through the diode will be less than 10uA. This is called leakage current. A
leaky zener is one that has been damaged such that the reverse leakage current
at voltages below the zener test voltage is a lot higher than normal. It
frequently happens through momentary current surges that exceed what the xener
is capable of absorbing, which damages the diode.

Good luck
Chris

Thanks Chris

Much appreciated

Gordon W
 
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