DDR4 DQ 的 VOH_DC >= 1.1vddq ？
为什么 DDR4 要求 DQ 的 VOH_DC >= 1.1*vddq?这个明显是达不到的嘛，那个大神可以解惑?
mark
Output Driver DC Linearity
Output linearity is not tested under system load conditions. The output driver's current is measured to the reference load in the data sheet. The output current is measured at defined VOL/VOH test points. VOL(DC) and VOH(DC) describe these reference points.
Note:
VOL(DC) and VOH(DC) are not test conditions. Output current is measured at VOL(DC) and VOH(DC) test points for verification of output drive and linearity.
了乎?
谢谢小编，这段我在镁光的一片文档里面也看到了，但是如果这个点纯粹是为了测试驱动电流或者说是输出阻抗，不是一个实际可以测得的值得话，为啥安捷伦示波器厂家会把这个当做VOH_DC测试的判决标准呢?在实际项目测试中不会pass的啊
美光（Micron）的文檔還有這段話：
Defining System VOL and VOH
The SDRAM is not required to achieve the VOL and VOH values stated in the data sheet. Actual system VOL and VOH are determined by the output drive from SDRAM, coupled with the load being driven. System VOL and VOH are usage conditions, not DDR3 SDRAM specifications. Those values are determined by RONdrive and ODT or the load being driven.
哦?