标题: DDR4 DQ 的 VOH_DC >= 1.1vddq ?? [打印本页] 作者: kobeismygod 时间: 2017-2-22 18:57 标题: DDR4 DQ 的 VOH_DC >= 1.1vddq ?? 本帖最后由 超級狗 于 2017-2-22 21:22 编辑 % H2 u+ b" M7 ]( @; E! t& Z3 Q! X
: P% X( `; {" [" Q1 ^8 \' x1 k
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？作者: tiny丨Y 时间: 2017-2-22 19:41
mark作者: 超級狗 时间: 2017-2-22 21:16 本帖最后由 超級狗 于 2017-2-23 08:55 编辑 I4 f0 w8 A" E1 `
; h* |! S- @' Y; z Output Driver DC Linearity , l9 x) r! d0 \! \* e0 z. fOutput 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 V[sub]OL[/sub]/V[sub]OH[/sub] test points. V[sub]OL(DC)[/sub] and V[sub]OH(DC)[/sub] describe these reference points. % P1 C/ L, B f2 }% |( ]1 }. `' {5 v) S6 p& q0 q% u
Note: 1 k* a0 x; X* v, xV[sub]OL(DC)[/sub] and V[sub]OH(DC)[/sub] are not test conditions. Output current is measured at V[sub]OL(DC)[/sub] and V[sub]OH(DC)[/sub] test points for verification of output drive and linearity. 4 E0 b8 o# m! S) `. u' a 6 P6 M# f. U) q7 d/ d了乎？ ) C) R( F4 W/ x 5 U* F* Q' m. I" x& L5 i% C1 X9 A( v. S 作者: kobeismygod 时间: 2017-2-23 09:56
超級狗 发表于 2017-2-22 21:16 $ n% ^7 O3 n% XOutput Driver DC Linearity7 R _3 x" {4 u" L x
Output linearity is not tested under system load conditions. The output ...
7 B; F4 b3 r. q9 N美光（Micron）的文檔還有這段話： 3 O% Y. ` R) a6 m( Q6 H 4 x$ Z0 l1 ]5 \9 j! ^Defining System V[sub]OL[/sub] and V[sub]OH[/sub] % ?3 T. ]6 F" h: j) RThe SDRAM is not required to achieve the V[sub]OL[/sub] and V[sub]OH[/sub] values stated in the data sheet. Actual system V[sub]OL[/sub] and V[sub]OH[/sub] are determined by the output drive from SDRAM, coupled with the load being driven. System V[sub]OL[/sub] and V[sub]OH[/sub] are usage conditions, not DDR3 SDRAM specifications. Those values are determined by R[sub]ONdrive[/sub] and ODT or the load being driven. 8 T, p/ ^$ `' a$ o2 R4 P5 v0 y% F" S; m! j, y5 i ' P4 B1 a5 w( I/ u作者: EDA-Q 时间: 2017-4-11 10:58
哦？作者: futures3031 时间: 2018-6-21 10:07
sodimm
" x& L5 i% C1 X9 A( v. S
