Memory Power Consumption - IDD modes and utilization rates
Estimate memory power based on DRAM IDD modes and utilization rates
Case 1: Based on a high memory utilization shown below:
a) one rank is in active state per channel 70-80% of the time, IDD7A
b) All other ranks are in active standby mode IDD3N
Power estimation example for 2 ECC DIMMs (36 DRAMs per 2 rank DIMM)
in a single channel (72 DRAMs total per system)
DDR power = (18 Active + 54 Standby + PLLs + registers) x VDD
DDR2 power = (18 Active + 18 ODT + 36 Standby + PLLs + registers) x VDD
Active = IDD7 x (70 or 80%, Standby = IDD3N
ODT = ODT current (Note: Rd/Wr Term power =70-140mw/DRAM during active mode only
PLLs = sum of the PLL currents
Registers = sum of all current from the registers
AMB =AMB power (if FBDIMM, PLL and registers not used)
Case 2: Based on an average memory utilization shown below:
a) one rank is in active state per channel 30% of the time, IDD7A
b) All other ranks are in precharge standby mode 30% of the time, IDD2F or
IDD2Q
c) All rank in precharge power down 40% of the time, IDD2P
Power estimation example for 2 ECC DIMMs (36 DRAMs per 2 rank DIMM)
in a single channel (72 DRAMs total per system)
DDR power = (18 Active + 54 Standby + PLLs + registers) x VDD
DDR2 power = (18 Active + 18 ODT + 36 Standby +PLLs + registers) x VDD
Active = IDD7 x 30%, Standby = IDD2F or IDD2Q x 30%
Precharge = IDD2P X 40%,
ODT = ODT current (Note: Rd/Wr Term power =70-140mw/DRAM)
PLLs = sum of the PLL currents
Registers = sum of all current from the registers
AMB =AMB power (if FBDIMM, PLL and registers not used)
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to help computer hardware board designers with DRAM memory subsystems.
This information is provided as a courtesy by Virtium Technology.
www.virtium.com
