Rev. 0.8 / Oct. 2007

15

3.3.3 OCD default characteristics

Description

Parameter

Min

Nom

Max

Unit

Notes

Output impedance

See full strength default

driver characteristics

ohms

1

Output impedance step size for OCD calibration

0

1.5

ohms

6

Pull-up and pull-down mismatch

0

4

ohms

1,2,3

Output slew rate

Sout

1.5

-

5

V/ns

1,4,5,6,7,8

Note

1. Absolute Specifications ( Toper; VDD = +1.8V ±0.1V, VDDQ = +1.8V ±0.1V). DRAM I/O specifications for

timing,voltage, and

slew rate are no longer applicable if OCD is changed from default settings. Please refer to the Device Operation &

Timing Diagram

of DDR2 for the Full Strength Default Driver Characteristics.

2. Impedance measurement condition for output source dc current: VDDQ=1.7V; VOUT=1420mV; (VOUT-VDDQ)/Ioh

must be less than 23.4 ohms for values of VOUT between VDDQ and VDDQ-280mV. Impedance measurement

condition for output sink

dc current: VDDQ = 1.7V; VOUT = 280mV; VOUT/Iol must be less than 23.4 ohms for values of VOUT between 0V

and 280mV.

3. Mismatch is absolute value between pull-up and pull-dn, both are measured at same temperature and voltage.

4. Slew rate measured from vil(ac) to vih(ac).

5. The absolute value of the slew rate as measured from DC to DC is equal to or greater than the slew rate as

measured from AC to AC. This is guaranteed by design and characterization.

6. This represents the step size when the OCD is near 18 ohms at nominal conditions across all process corners/

variations and represents only the DRAM uncertainty. A 0 ohm value(no calibration) can only be achieved if the

OCD impedance is 18 ohms +/- 0.75 ohms under nominal conditions.

Output Slew rate load:

7. DRAM output slew rate specification applies to 400 , 533 and 667 MT/s speed bins.

8. Timing skew due to DRAM output slew rate mis-match between DQS / DQS and associated DQs is included in

tDQSQ and tQHS specification.

VTT

25 ohms

Output

(Vout)

Reference

point