> I am using DDR buffer with internal termination of 50 ohm. > So when the voltage range is between 0 to VCC, I do not have a zero current. > Is that current should be treated as a leakage current? It might be actual leakage current or terminator (pullup/pulldown) current or something else. > If the power clamp and gnd clamp are overlapped (in the range 0 - vcc). > I will get the same current results for this range in the power and gnd clamp. And I will have double counting. > Should I write the current results for this range only in one of the clamps (gnd or power), > And in the second writing zeroes? This is a little trickier, and I may not be the best person to answer it. But here is how I see it. You need to decide which table(s) to put that current into. Where the current doesn't change with Vcc, then it should go in the Gnd clamp table. Where the current curve tracks with Vcc, it should go in the Power clamp table. That is mainly how to decide. The simulator takes the data from the Power clamp table and offsets them by the power supply voltage, which has some min/typ/max range. When you have a device with very little current between 0 and Vcc, it's easy to truncate the currents in that broad range where they are near zero, and assign the lower part of the current curve to the gnd clamp and the upper part to power clamp. In your case you may need to do some "fudging" to make a smooth transition between one table and the other, so that when the two clamp curves are added together, with min/typ/max Vcc, you don't end up with gaps or overlapping areas that have discontinuities. If you know something about the inner workings of your device, enough to say that this portion of the current is due to a pullup device to Vcc but that portion of the current is going through some sort of device to Gnd, then you can separate those portions out from the total current and assign each to the corresponding clamp tables ... in such a way that the total adds up to the total device current. I may not be the best at describing this. Hopefully you get the idea. Andy -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. -------------------------------------------------------------------- |For help or to subscribe/unsubscribe, e-mail majordomo@eda-stds.org |with the appropriate command message(s) in the body: | | help | subscribe ibis <optional e-mail address, if different> | subscribe ibis-users <optional e-mail address, if different> | unsubscribe ibis <optional e-mail address, if different> | unsubscribe ibis-users <optional e-mail address, if different> | |or e-mail a request to ibis-request@eda-stds.org. | |IBIS reflector archives exist under: | | http://www.eda-stds.org/pub/ibis/email_archive/ Recent | http://www.eda-stds.org/pub/ibis/users_archive/ Recent | http://www.eda-stds.org/pub/ibis/email/ E-mail since 1993Received on Wed Aug 5 10:33:40 2009
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