Elantec EL2142C line receiver latchup problem

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2 total messages Started by David L. Jones Mon, 08 Apr 2002 05:42

#22583

Author: David L. Jones
Date: Mon, 08 Apr 2002 05:42

16 lines
1809 bytes

Has anyone had any problems with the inputs on the Elantec EL2142C
diff line receiver latching up and causing excess current drain?
I appear to be having this problem, and the chip is drawing up to an
extra 100mA for some reason.
I'm using the device in the standard twisted pair application as shown
in the data sheet (single resistor feedback), with a terminated diff
input (but no signal connected). The current drops back to normal if I
single-end one of the inputs to ground.
It's not the chip, I've changed it, power rails are clean and
decoupled, no oscillation, Vref at ground, and the output is not
driving any significant load.

Any ideas?

Thanks
Dave :)

Re: Elantec EL2142C line receiver latchup problem

#22582

Author: Glenn Gundlach
Date: Tue, 09 Apr 2002 05:11

32 lines
2728 bytes

dljones@ozemail.com.au (David L. Jones) wrote in message news:<734fad6f.0204072142.5b3c9d7e@posting.google.com>...
> Has anyone had any problems with the inputs on the Elantec EL2142C
> diff line receiver latching up and causing excess current drain?
> I appear to be having this problem, and the chip is drawing up to an
> extra 100mA for some reason.
> I'm using the device in the standard twisted pair application as shown
> in the data sheet (single resistor feedback), with a terminated diff
> input (but no signal connected). The current drops back to normal if I
> single-end one of the inputs to ground.
> It's not the chip, I've changed it, power rails are clean and
> decoupled, no oscillation, Vref at ground, and the output is not
> driving any significant load.
> 
> Any ideas?
> 
> Thanks
> Dave :)
You're using the chip as in figure 1 of the Elantec .PDF at

http://www.elantec.com/pages/search.cgi

You're staying within the +/- 2 volt differential input range and the
common mode range ? The 2 resistor version implies gain. Are you
driving the output beyond its range? I'm not Elantecs biggest fan but
their stuff usually works as stated (EXCEPT for the EL4390 which does
NOT work as shown in fig 2) From the sound of it I would bet 1 (or
both) of your inputs are outside of the common mode range. The fact
that 1 input to ground restores it suggests a common mode problem.
Since I AM Analog devices biggest fan, did you check the AD830 or
AD8129/8130? Will be interested in hearing your progress.

Glenn Gundlach

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