IS61QDPB44M18B/B1/B2

IS61QDPB42M36B/B1/B2

Integrated Silicon Solution, Inc.- www.issi.com

Rev. A

09/02/2014

6

ODT (On Die Termination)

On Die Termination (ODT) is a feature that allows a SRAM to change input resistive termination condition by ODT pin

which function can have three status, High, Low, and Floating. Each status can have different ODT termination value

that tracks the value of RQ (Refer to the table of Fig1) and ODT of QUADP is always turned on during the read and

write function after ODT level to connect with ODT resistor is forced.

Fig1. Functional representation of ODT

Notes

1. Allowable range of RQ to guarantee impedance matching a tolerance of ±20% is 175

Ω<RQ<350Ω.

2. Allowable range of RQ to guarantee impedance matching a tolerance of ±20% is 175

Ω<RQ<250Ω.

3. ODT control pin is connected to VDDQ through 3.5k

Ω. Therefore it is recommended to connect it to VSS

through less than 100

Ω to make it low.

4. ODT control pin is connected to VSS through 3.5k

Ω. Therefore it is recommended to connect it to VDDQ

through less than 100

Ω to make it high.

ODT PIN

For option1 case, low input level of ODT pin can select strong (RQ

high input level of ODT pin can select weak (RQ

BWx# and if ODT pin is on floating condition, it set weak (RQ

pull-up resistor internally.

For option2 case, high input level of ODT pin can select weak (RQ

range (175

Ω<RQ<250Ω) with D0 to Dn, BWx# and low input level or floating of ODT pin can select disable of the ODT

function.

R1

R2

R3

Option1

3

0.3x

RQ

1

0.6x

RQ

2

0.6x

RQ

2

Option2

4

ODT

disable

0.6x

RQ

2

ODT

disable

PAD

ODT=L

ODT=L

ODT=H

ODT=H

ODT=Floating

ODT=Floating

VDDQ

VSS

VDDQ

VSS

VDDQ

VSS

R1x2

R1x2

R2x2

R2x2

R3x2

R3x2