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Politics : Formerly About Advanced Micro Devices -- Ignore unavailable to you. Want to Upgrade?

To: Petz who wrote (27103)	12/23/1997 10:52:00 PM
From: Yousef	Read Replies (2) \| Respond to of 1572916

John, Re: "Since power consumption generally increases as the square of frequency ..." This is incorrect, John ... The power increase linearly with the frequency. You must be thinking about how power scales with voltage. Power ~ CV^2F Performance ~ I/(CV) This is why "jacking up" the supply voltage up to meet perfromance targets will never get you into the notebook market. Make It So, Yousef

To: Petz who wrote (27103)	12/23/1997 11:44:00 PM
From: Time Traveler	Read Replies (1) \| Respond to of 1572916

Petz, Power dissipation between 0.25um and 0.35um: By now everyone knows: P = C * V^2 * f, where P = power dissipation, V = applied voltage to the core, F = core operating frequency, and C = geometry constant. In 0.35um K6, V = 3.2V, f = 233, and P = 28.3W (when you design anything to meet a spec, you always have to use the worst case, and I hope you know this), these hints a C = 1.19E-2 with an appropriate unit of Watt/Volt^2/MHz if you want to get down to more details. In 0.25um, C = 1.19E-2 * (0.25 / 0.35)^2 = 6.07E-3, V = 3.2 * (0.25 / 0.35) = 2.3, And say f = 300Mhz, We have P = 6.07E-3 * 2.3^2 * 300 = 9.6 watts worst case for K6 with 0.25um process. Now, what is the theoretical limit of K6 at 0.25um? Take the limit at 0.35um of 233MHz: 233 * (0.35 / 0.25)^2 = 466 MHz. At f = 466MHz, the power dissipation (again worst case) becomes 15 watts. Yes, it looks like the Socket 7 is very capable of dissipating this meager 15 watts, but the die size is reduced to 68 / 162 = 0.42, that means the junction-to-case thermal constant is increased by 162 / 68 = 2.4! Now, can you keep the junction temperature at a satisfactory level? Slot I has lower case-to-ambient thermal constant, and that extra bit of advantage helps. John.