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EDE1104ACSE-5C-E Datasheet(PDF) 46 Page - Elpida Memory |
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EDE1104ACSE-5C-E Datasheet(HTML) 46 Page - Elpida Memory |
46 / 82 page EDE1104ACSE, EDE1108ACSE, EDE1116ACSE Data Sheet E0975E50 (Ver.5.0) 46 Extended Mode Register Set for OCD Impedance Adjustment OCD impedance adjustment can be done using the following EMRS mode. In drive mode all outputs are driven out by DDR2 SDRAM and drive of RDQS is dependent on EMRS bit enabling RDQS operation. In Drive (1) mode, all DQ, DQS (and RDQS) signals are driven high and all /DQS signals are driven low. In drive (0) mode, all DQ, DQS (and RDQS) signals are driven low and all /DQS signals are driven high. In adjust mode, BL = 4 of operation code data must be used. In case of OCD calibration default, output driver characteristics follow approximate nominal V/I curve for 18 Ω output drivers, but are not guaranteed. If tighter control is required, which is controlled within 18 Ω ± 3Ω driver impedance range, OCD must be used. OCD applies only to normal full strength output drive setting defined by EMRS (1) and if reduced strength is set, OCD default output driver characteristics are not applicable. When OCD calibration adjust mode is used, OCD default output driver characteristics are not applicable. [OCD Mode Set Program] A9 A8 A7 Operation 0 0 0 OCD calibration mode exit 0 0 1 Drive (1) DQ, DQS, (RDQS) high and /DQS low 0 1 0 Drive (0) DQ, DQS, (RDQS) low and /DQS high 1 0 0 Adjust mode 1 1 1 OCD calibration default OCD Impedance Adjustment To adjust output driver impedance, controllers must issue the ADJUST EMRS command along with a 4bit burst code to DDR2 SDRAM as in OCD Adjustment Program table. For this operation, burst length has to be set to BL = 4 via MRS command before activating OCD and controllers must drive this burst code to all DQs at the same time. DT0 in OCD Adjustment Program table means all DQ bits at bit time 0, DT1 at bit time 1, and so forth. The driver output impedance is adjusted for all DDR2 SDRAM DQs simultaneously and after OCD calibration, all DQs and DQS's of a given DDR2 SDRAM will be adjusted to the same driver strength setting. The maximum step count for adjustment is 16 and when the limit is reached, further increment or decrement code has no effect. The default setting may be any step within the 16-step range. When Adjust mode command is issued, AL from previously set value must be applied. [OCD Adjustment Program] 4bits burst data inputs to all DQs Operation DT0 DT1 DT2 DT3 Pull-up driver strength Pull-down driver strength 0 0 0 0 NOP NOP 0 0 0 1 Increase by 1 step NOP 0 0 1 0 Decrease by 1 step NOP 0 1 0 0 NOP Increase by 1 step 1 0 0 0 NOP Decrease by 1 step 0 1 0 1 Increase by 1 step Increase by 1 step 0 1 1 0 Decrease by 1 step Increase by 1 step 1 0 0 1 Increase by 1 step Decrease by 1 step 1 0 1 0 Decrease by 1 step Decrease by 1 step Other combinations Reserved |
Similar Part No. - EDE1104ACSE-5C-E |
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