Keysight Technologies D9020DDRC, Manual

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16 Data Timing Tests
282 DDR2(+LP) Compliance Testing Methods of Implementation
Measurement Algorithm
1 Acquire and split read and write burst of the acquired signal.
2 Take the first valid WRITE burst found.
3 Find all valid rising DQ crossings that cross V
IL(DC)
in the burst.
4 Find all valid falling DQ crossings that cross V
IH(DC)
in the same burst.
5 For all DQ crossings found, locate all prior DQS rising crossings that cross V
IH(AC)
and all prior
DQS falling crossings that cross V
IL(AC)
.
6 tDH1 is defined as the time between the DQ crossing and the DQS crossing.
7 Collect all tDH1.
8 Find the worst tDH1 among the measured values and report the value as the test result.
9 Measure the nominal slew rate on the DQ and DQS edges where worst tDH1 was found.
• For DQ Falling, Slew Rate = (V
REF
- V
IL(AC)
) / tF
• For DQ Rising, Slew Rate = (V
IH(AC)
- V
REF
) / tR
tF and tR are the transition time respectively.
• For DQS Rising, Slew Rate = (V
HITHRES
- 0V) / tR
• For DQS Falling, Slew Rate = (0V - V
LOTHRES
) / tF
tF and tR are the transition time respectively.
10 Report the nominal slew rate for DQ and DQS.
11 Measure the tangent slew rate on the DQ and DQS edges where worst tDH1 was found. The
measurement is similar to nominal slew rate, except the transition time is broken into ten parts
and the slew rate is measured from a pivot point (V
REF
or 0V) to each of the ten points. Tangent
slew rate is the maximum slew rates measured.
12 Report tangent slew rate for DQ and DQS.