EM68B08CWAH-18H Datasheet, PDF (13/57 Pages) Etron Technology, Inc. – 64M x 8 bit DDRII Synchronous DRAM (SDRAM)

EtronTech
EM68B08CWAH
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,
DQS/DQS#, DM 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 4. Functional representation of ODT
V_DDQ
V_DDQ
V_DDQ
SW1
SW2
SW3
DRAM
Input
Buffer
Rval1
Rval1
Rval2
Rval2
Rval3
Input
pin
Rval3
SW1
SW2
SW3
V_SSQ
V_SSQ
V_SSQ
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, DQS# pins
Table 9. ODT DC Electrical Characteristics
Parameter/Condition
Symbol Min. Nom. Max. Unit Note
Rtt effective impedance value for EMRS(A6,A2)=0,1;75Ƹ Rtt1(eff) 60
75
90
Ƹ1
Rtt effective impedance value for EMRS(A6,A2)=1,0;150Ƹ Rtt2(eff) 120
150
180
Ƹ1
Rtt effective impedance value for EMRS(A6,A2)=1,1;50Ƹ Rtt3(eff) 40
50
60
Ƹ1
Rtt mismatch tolerance between any pull-up/pull-down pair Rtt(mis) -6
-
6
2
NOTE 1: Measurement Definition for Rtt(eff):
Apply V_IH (ac) and V_IL (ac) to test pin seperately, then measure current I(V_IH(ac)) and I(V_IL(ac))
respectively.
Rtt(eff)= ^{VIH(ac) − VIL (ac)}
I(V_IH(ac))-I(V_IL (ac))
NOTE 2: Measurement Defintion for Rtt (mis): Measure voltage (VM) at test pin (midpoint) with no load.
Rtt(mis)=
⎛
⎜
⎝
2xVM
V_DDQ
−
⎞
1_⎟
⎠
×100%
Etron Confidential
13
Rev. 1.2
Nov. /2013