Rev. 0.2 / Mar. 2005

13

512Mb A-ver. DDR2 SDRAM

3.2.4 Differential Input AC logic Level

3.2.5 Differential AC output parameters

Symbol

Parameter

Min.

Max.

Units

Notes

ac differential input voltage

0.5

VDDQ + 0.6

V

1

ac differential cross point voltage

0.5 * VDDQ - 0.175

0.5 * VDDQ + 0.175

V

2

1. VIN(DC) specifies the allowable DC execution of each input of differential pair such as CK, CK, DQS, DQS, LDQS, LDQS, UDQS

and UDQS.

2. VID(DC) specifies the input differential voltage |VTR -VCP | required for switching, where VTR is the true input (such as CK,

DQS, LDQS or UDQS) level and VCP is the complementary input (such as CK, DQS, LDQS or UDQS) level. The minimum value

is equal to VIH(DC) - V IL(DC).

Note:

1. VID(AC) specifies the input differential voltage |VTR -VCP | required for switching, where VTR is the true input signal (such as

CK, DQS, LDQS or UDQS) and VCP is the complementary input signal (such as CK, DQS, LDQS or UDQS). The minimum value

is equal to V IH(AC) - V IL(AC).

2. The typical value of VIX(AC) is expected to be about 0.5 * VDDQ of the transmitting device and VIX(AC) is expected to track

variations in VDDQ . VIX(AC) indicates the voltage at which differential input signals must cross.

Symbol

Parameter

Min.

Max.

Units

Notes

ac differential cross point voltage

0.5 * VDDQ - 0.125

0.5 * VDDQ + 0.125

V

1

Note:

Crossing point

< Differential signal levels >