Leaky zener diodes

G

Gordon W

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

Gordon W
 
Subject: Leaky zener diodes
From: "Gordon W" welch@gil.com.au
Date: 9/2/2004 5:32 PM Central Daylight Time
Message-id:
4138d2d4$0$18336$61c65585@uq-127creek-reader-03.brisbane.pipenetworks.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
 
CFoley1064 <cfoley1064@aol.com> wrote in message
news:20040905093943.22172.00000168@mb-m18.aol.com...
Subject: Leaky zener diodes
From: "Gordon W" welch@gil.com.au
Date: 9/2/2004 5:32 PM Central Daylight Time
Message-id:

4138d2d4$0$18336$61c65585@uq-127creek-reader-03.brisbane.pipenetworks.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
Thanks Chris

Much appreciated

Gordon W
 

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