MT41J256M8HX-187ED Datasheet, PDF (60/211 Pages) Micron Technology – 2Gb: x4, x8, x16 DDR3 SDRAM Features

2Gb: x4, x8, x16 DDR3 SDRAM
Output Driver Impedance
Output Driver Impedance
The output driver impedance is selected by MR1[5,1] during initialization. The selected
value is able to maintain the tight tolerances specified if proper ZQ calibration is per-
formed. Output specifications refer to the default output driver unless specifically sta-
ted otherwise. A functional representation of the output buffer is shown below. The out-
put driver impedance R_ON is defined by the value of the external reference resistor RZQ
as follows:
• R_ON,x = RZQ/y (with RZQ = 240Ω rx Ω or 40Ω with y = 7 or 6, respectively)
The individual pull-up and pull-down resistors R_ON(PU) and R_ON(PD) are defined as fol-
lows:
• R_ON(PU) = (V_DDQ - V_OUT)/|I_OUT|, when R_ON(PD) is turned off
• R_ON(PD) = (V_OUT)/|I_OUT|, when R_ON(PU) is turned off
Figure 26: Output Driver
Chip in drive mode
Output driver
To
other
circuitry
such as
RCV, . . .
I_PU
R_ON(PU)
R_ON(PD)
I_PD
V_DDQ
I_OUT
DQ
V_OUT
V_SSQ
PDF: 09005aef826aaadc
2Gb_DDR3_SDRAM.pdf - Rev. Q 04/13 EN
60
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