Re: [buildcheapeeg] Re: Input protection

From: Joerg Hansmann (info_at_jhansmann.de)
Date: 2002-01-09 00:09:49


Hi,

----- Original Message -----
From: sleeper75se <sleeper75se_at_yahoo.se>
To: <buildcheapeeg_at_yahoogroups.com>
Sent: Tuesday, January 08, 2002 2:29 PM
Subject: [buildcheapeeg] Re: Input protection

...
> One question about those FET-diodes... they are only connected to V+.
> Shouldn't there be diodes to V- as well?

I am confused about this detail too.
The gate-source breakdown voltage for Ig=1uA is -35 to -40 V minimum for
the 2N4393 (Temic/siliconix datasheet). This is from the absolute
maximum ratings and I am not sure if the breakdown is reversible
like in z-diodes.
If it were z-diode like, it would not be useful anyway, because the
internal clamping diodes to v- (see block diagram) would conduct long before
the gate-source breakdown occurs.

> Of course, the people at
> Linear know what they are doing...

Do not be too credulous. To err is human.

In case of doubt an email to Linear Technology will help.

Regards,

Joerg



picture

This archive was generated by hypermail 2.1.4 : 2002-07-27 12:28:36 BST