AS4C64M8D2 datasheet(13/59 Pages) ALSC

13 / 59 page

AS4C64M8D2

Confidential

Rev. 1.0

Feb. /2014

 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

SW1

Rval1

VDDQ

SW1

Rval1

VSSQ

SW3

Rval3

VDDQ

SW3

Rval3

VSSQ

SW2

Rval2

VDDQ

SW2

Rval2

VSSQ

Input

DRAM

Input

Buffer

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;75Ω

Rtt1(eff)

Rtt effective impedance value for EMRS(A6,A2)=1,0;150Ω Rtt2(eff)

120

150

180

Rtt effective impedance value for EMRS(A6,A2)=1,1;50Ω

Rtt3(eff)

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 separately, then measure current I(VIH(ac)) and I(VIL(ac)) respectively.

( )



V ac

Rtt(eff)=

I(V (ac))-I(V (ac))

NOTE 2: Measurement Definition for Rtt (mis): Measure voltage (VM) at test pin (midpoint) with no load.

1 100%









DDQ

2xVM

Rtt(mis)=

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