Re: Input protection

From: sleeper75se (sleeper75se_at_yahoo.se)
Date: 2002-01-09 10:15:12


--- In buildcheapeeg_at_yahoogroups.com, "Joerg Hansmann" <info_at_jhansmann.de> wrote:
> 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.

And minimizing the number of inquiries is cost effective for the
company. If they made a mistake, I'm sure someone has pointed it out
to them by now.

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

Yep, I'm working on that now. I'm asking about alternatives to 2N4393
as well.

/Andreas



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