K4N56163QF Datasheet, PDF (31/73 Pages) Samsung semiconductor – 256Mbit gDDR2 SDRAM

K4N56163QF-GC
256M gDDR2 SDRAM
ODT (On Die Termination)
On Die Termination (ODT) is a feature that allows a DRAM to turn on/off termination resistance. For x16 configuration
ODT is applied to each DQ, UDQS/UDQS, LDQS/LDQS, UDM, and LDM signal via the ODT control pin. The ODT feature
is designed to improve signal integrity of the memory channel by allowing the DRAM controller to independently turn on/off
termination resistance for any or all DRAM devices.
The ODT function is supported for ACTIVE and STANDBY modes, and turned off and not supported in SELF REFRESH
mode.
Functional Representation of ODT
VDDQ
sw1
DRAM
Input
Buffer
Rval1
Rval1
VDDQ
sw2
Rval2
Rval2
Input
Pin
sw1
VSSQ
sw2
VSSQ
Switch sw1 or sw2 is enabled by ODT pin.
Selection between sw1 or sw2 is determined by “Rtt (nominal)” in EMRS
Termination included on all DQs, DM, DQS and DQS pins.
Target Rtt (ohm) = (Rval1) / 2 or (Rval2) / 2
ODT DC Electrical Characteristics
Parameter/Condition
Rtt effective impedance value for EMRS(A6,A2)=0,1; 75 ohm
Rtt effective impedance value for EMRS(A6,A2)=1,0; 150 ohm
Rtt mismatch tolerance between any pull-up/pull-down pair
Symbol
Rtt1(eff)
Rtt2(eff)
Rtt(mis)
Min
60
120
-3.75
Nom
75
150
Max
90
180
+3.75
Units
ohm
ohm
%
Notes
1
1
1
Note 1: Test condition for Rtt measurements
Measurement Definition for Rtt(eff): Apply V_IH (AC) and V_IL (AC) to test pin separately, then measure current I(V_IH (AC)) and I( V_IL (AC))
respectively. V_IH (AC), V_IL (AC), and VDDQ values defined in SSTL_18
V_IH (AC) - V_IL (AC)
Rtt(eff) =
I(V_IH (AC)) - I(V_IL (AC))
Measurement Definition for VM: Measure voltage (VM) at test pin (midpoint) with no load.
delta VM =
2 x Vm
- 1 x 100%
VDDQ
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Rev 1.6 (Apr. 2005)