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Technology Stocks : Rambus (RMBS) - Eagle or Penguin -- Ignore unavailable to you. Want to Upgrade?

To: John Walliker who wrote (33604)	11/2/1999 5:39:00 PM
From: Bilow	Read Replies (1) \| Respond to of 93625

Hi John Walliker; Re those Rambus channel output currents... The RAC also is specified to drive 30 to 90mA outputs, just like the RDRAM are: rambus.com My guess is that Intel would use 90mA in their calculations for ground bounce &c. Your numbers are nominal for the design as it is being used, (but do not take into account worst case for either the resistance or the voltage), but that the Rambus architecture is designed to allow double termination of the bus. That is why the 90mA is there, it allows a doubly terminated 28 ohm bus to work over the full range of possible reference and termination voltages. By doubling the output currents, you could drive a doubly terminated bus, and this would eliminate the problems with output drive compliance that we have discussed here recently. Since the designers cannot be sure of what bus topology is going to be used (that is, single or doubly terminated), they are going to design for the worst case, which is a somewhat under resistance, over voltage, doubly terminated line. Thus 90mA. Do you have an explanation of why the 90mA is in all the Rambus specs? The above seems like the one to me. -- Carl