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The SDRAM devices used in the RAM expansion modules must be self-refresh type devices for operation from a 3.3-V power supply. The speed of the SDRAM devices must be 125 MHz or greater (8 ns access time).
The devices are programmed to operate with a CAS latency of 3. At that CAS latency, the access time from the clock transition must be 6 ns or less. The burst length must be at least 4 and the minimum clock delay for back-to-back random column access cycles must be a latency of 1 clock cycle.
When the computer is in sleep mode, the RAM modules are in self-refresh mode and the maximum power-supply current available for each bank of SDRAM is 8 mA (see the section RAM SO-DIMM Electrical Limits). Developers should specify SDRAM devices with low power specifications so as to stay within that limit.