Speed CAS Latency tRCD(min) tRP(min) tRC(min) DDR2-667 5-5-5 5 15 15 54 DDR2-533 4-4-4 4 15 15 55 DDR2-400 3-3-3 3 15 15 55 Units tCK ns ns ns • JEDEC standard 1.8V ± 0.1V Power Supply • VDDQ = 1.8V .