EtronTech
EM68916CWQA
z ODT (On Die Termination)
On Die Termination (ODT) is a feature that allows a DRAM to turn on/off termination resistance for 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. It is turned off and not supported in SELF
REFRESH mode.
Figure 5. Functional representation of ODT
VDDQ
VDDQ
VDDQ
SW1
SW2
SW3
Rval1
Rval2
Rval3
DRAM
Input
Input
pin
Buffer
Rval1
SW1
Rval2
SW2
Rval3
SW3
VSSQ
VSSQ
VSSQ
Switch (sw1, sw2, sw3) is enabled by ODT pin.
Selection among sw1, sw2, and sw3 is determined by “Rtt (nominal)” in EMR.
Termination included on all DQs, DM, DQS, and DQS# pins
Table 11.ODT DC Electrical Characteristics
Parameter/Condition
Symbol
Min
Nom
Max
Unit Note
Rtt effective impedance value for EMRS(A6,A2)=0,1;75Ω
Rtt effective impedance value for EMRS(A6,A2)=1,0;150Ω
Rtt effective impedance value for EMRS(A6,A2)=1,1;50Ω
Ω
Ω
Ω
%
Rtt1(eff)
Rtt2(eff)
Rtt3(eff)
60
120
40
75
150
50
-
90
180
60
6
1
1
1
2
Rtt mismatch tolerance between any pull-up/pull-down pair Rtt(mis)
-6
NOTE 1: Measurement Definition for Rtt(eff):
Apply VIH (ac) and VIL (ac) to test pin seperately, then measure current I(VIH(ac)) and I(VIL(ac))
respectively.
V (ac) − V (ac)
IH
IL
Rtt(eff)=
I(V (ac))-I(V (ac))
IH
IL
NOTE 2: Measurement Defintion for Rtt (mis): Measure voltage (VM) at test pin (midpoint) with no load.
⎛
⎜
⎝
⎞
2xVM
VDDQ
Rtt(mis)=
−1 ×100%
⎟
⎠
Etron Confidential
15
Rev. 1.1
Apr. 2009
ETRON [ ETRON TECHNOLOGY, INC. ]
