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From: "Zhong Pan"
Subject: Re: Help: Why 1.5V output in Samsung SRAM K6R1016C1C(KM6161002C) ?
Date: Fri, 27 Dec 2002 13:23:55 -0800
Organization: University of California, Davis
NNTP-Posting-Date: Fri, 27 Dec 2002 21:23:56 +0000 (UTC)
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
"John Devereux" wrote in message
> "Zhong Pan" wrote:
> >Thanks John. That would be my guess too (no power or chip blown up) if I
> >hadn't seen correct data being written into and read out of the chip.
> >can write into the chip and read out of the chip correctly, according to
> >measurement done by an Agilent Infiniium DCA. But the voltage is low, and
> >suspect that it is the reason that causes some glitches in my next stage,
> >which is a DAC. This still puzzles me.
> Well, things can still partially work even with no power
> supply. The power comes through the protection diodes on the
> I/O pins. Similarly with the "blown up" theory; it could
> still mostly work.
> Can you measure the correct supply voltages (5V and ground)
> at the chip pins?
Yes, yesterday I measured all the 5V and GND pins and they are all correct.
> >One thought: could it be that I am not measuring the right voltage at
> >My measurement at the SMA connectors driven by a BERT shows a HI voltage
> >2.5V, and power source current does not change. But while measuring the
> >chip, the power source current will increase for around dozens of mA. Is
> >oscilliscope seen by the SRAM chip as a big load?
> If you've switched the scope to 50 ohms it will be a big
> load! So don't do that :)
I guess I AM using 50 ohms! All our coaxial cables are 50 ohms with SMA
We are just using a home-made probe connecting to the cable. The reason is
that we need
to measure from several Mb/s to 10Gb/s digital signal using the DCA. Do you
we can buy the right probe which can be connected to SMA?
In terms of the DCA itself, I am not sure if it is 50 ohms terminated. But I
we did have problem measuring ECL signals 'cause ECL is current output
instead of voltage.
Thanks and Happy New Year!
> John Devereux
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