[SI-LIST] Re: LA probes

I have mapped to CMOS logic family. The probe impedance is 20K. I am
seeing a voltage of 2.0 V on a static pin on which I was expecting 3.3V.


-----Original Message-----
From: olaney@xxxxxxxx [mailto:olaney@xxxxxxxx]=20
Sent: Monday, July 30, 2007 12:00 PM
To: prajitsnair@xxxxxxxxx
Cc: SRINIVASAN ANAND-B06739; si-list@xxxxxxxxxxxxx
Subject: Re: [SI-LIST] Re: LA probes

Does the logic analyzer allow you to specify the logic family
parameters?
 You might have the wrong setting, for instance PECL loading on a CMOS
signal.

Orin

On Mon, 30 Jul 2007 15:19:39 +0900 "PRAJIT S  NAIR"
<prajitsnair@xxxxxxxxx> writes:
> Dear Anand
> It may be happening because of probe loading. Please check your Probe=20
> Capacitance, Frequency of Operation and also Load impedance.
>=20
>=20
> Best Regards
> Prajit
>=20
>=20
> On 7/30/07, SRINIVASAN ANAND-B06739 <anand.srinivasan@xxxxxxxxxxxxx>
> wrote:
> >
> > Content-Type: text/plain;
> >        charset=3D"us-ascii"
> > Content-Transfer-Encoding: quoted-printable Hi All, I have a=20
> > problem. Given below is a topology that i have.=3D20
> >
> >
> >
> > =3D20
> >
> > =3D20
> >
> > I have a bidirectional bus which connects a FPGA to the CHIP. The=20
> > distance between them is 2 inches. Now to probe this bus, i have
> the
> > signals coming out to the right at a distance of about 6 inches.=20
> Note
> > that i am using active probes to probe this interface and there
> are NO
> > buffers on the line between the chip and LA probes. Now the
> problem is
> > that when the LA is plugged in I find that the strength of the
> signals
> > driven by the chip comes down from 3.3V to 2V. Without the LA
> plugged,
> > the signal strength remains intact. Could anyone help me in=20
> > understanding this? If a solution is possible to get around this,
> it
> > will be great.
> >
> > =3D20
> > Regards,
> > Anand
> >
> > =3D20
> >
> > =3D20
> >
> >
> >
> >
> > -- Binary/unsupported file stripped by Ecartis --
> > -- Type: image/jpeg
> > -- File: Outlook.jpg
> > -- Desc: Outlook.jpg
> >
> >
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>=20
>=20
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>=20
>=20
>=20
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