Datasheet

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 x 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 24: Output Driver
R
ON(PU)
R
ON(PD)
Output driver
To
other
circuitry
such as
RCV, . . .
Chip in drive mode
V
DDQ
V
SSQ
I
PU
I
PD
I
OUT
V
OUT
DQ
8Gb: x4, x8, x16 DDR3L SDRAM
Output Driver Impedance
56
Rev 2.0 June 2016
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