AS4C128M8D2 datasheet(13/59 Pages) ALSC

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AS4C128M8D2

Alliance Memory Inc. 551 Taylor Way, San Carlos, CA 94070

TEL: (650) 610-6800

FAX: (650) 620-9211

Alliance Memory Inc. reserves the right to change products or specification without notice.

Rev. 1.0

June 2013

 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#,

RDQS/RDQS#, 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#, RDQS and RDQS# pins

Table 10. 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 seperately, then measure current I(VIH(ac)) and I(VIL(ac)) respectively.

( )



V ac

Rtt(eff)=

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

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

1 100%









DDQ

2xVM

Rtt(mis)=

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