DDR3 ZQ
来源:互联网 发布:仿大牌的女装淘宝店 编辑:程序博客网 时间:2024/04/30 02:42
What is ZQ calibration - In DDR3, there are 2 different calibration commands to account for variations in the system environment for temperature, voltage, component drift. The ZQ calibration commands calibrate the DRAM's output drivers (Ron) and ODT values (Rtt),normally, using a precision 240 ohm (±1 percent) resistor connected from the DRAM's ZQ pin to ground.
Since the first ZQ calibration long (ZQCL) command issued takes 512 clocks to complete, it is often used during power-up initialization and reset. Subsequent ZQCL commands can be issued at any time the DRAM is idle and will only require 246 clocks.
The ZQ calibration short (ZQCS) requires 64 clocks to complete so it is used periodically when the DRAM is idle to perform calibrations to account for minor variations in voltage and temperature.Each ZQCS command can correct a minimum of 0.5% impedance error within 64 clocks. As a starting point for BIOS development, you candetermine the time interval between ZQCS commands, by calculating the ZQCS time interval as follows:
ZQCS time Interval = ZQCorrection of 0.5%/64 clocks / [(Tsensitivities x Tdriftrate) + (Vsensitivities x Vdriftrate)]
Use the Maximum values from the ODT temperature and voltage sensitivity table shown in the DRAM component specification/datasheet, but the driftrates are system dependant and will vary system environments (often determined by testing in an environmental lab).
Both ZQCL and ZQCS can be initiated at any time and often as required by the BIOS and memory controller to account for larger changes in the system environment. The ZQCL command is used when there is more impedance error correction required than a ZQCS can provide.
- DDR3 ZQ
- DDR3
- DDR之ZQ
- DDR之ZQ .
- DDR之ZQ
- DDR3笔记
- DDR3笔记
- ZQ门禁简要指南 Beta 0.8.1
- SDRAM DDR DDR2 DDR3
- DDR2 DDR3的区别
- DDR3内存技术原理
- DDR3学习笔记
- DDR2 DDR3的区别
- DDR3基本知识及测试 .
- DDR3 SPEC
- DDR3读写时序
- TI DDR3配置
- DDR3 ODT
- 『windows』用C/C++编写window服务
- HTTP协议与状态保持
- GlobalAlloc函数和new()的区别
- Qt单机版斗地主游戏
- 以太网
- DDR3 ZQ
- vmware server 1.0搭建共享存储
- Oracle 表管理1
- as3种常见的弹性效果公式以及波形运动等as3动画效果公式代码整理
- Hama运行pagerank
- java 创建线程的三种方法Callable,Runnable,Thread比较及用法
- The import ... cannot be resolved
- Java序列化与反序列化
- OCP-1Z0-052-V8.02-149题