Keysight Technologies D9020DDRC, Руководство пользователя

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16 Data Timing Tests
260 DDR2(+LP) Compliance Testing Methods of Implementation
Test References
See Table 41 - Timing Parameters by Speed Grade (DDR2-400 and DDR2-533) and Table 42 -
Timing Parameters by Speed Grade (DDR2-667 and DDR2-800) in the
JEDEC Standard JESD79-2E .
See Table 41 - Timing Parameters by Speed Grade (DDR2-1066) in the JESD208 .
Also see Table 108 - Data Setup and Hold Base- Values in the JESD208-2B .
PASS Condition
The worst measured tDS shall be within the specification limit.
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
IH(AC)
in the burst.
4 Find all valid falling DQ crossings that cross V
IL(AC)
in the same burst.
5 For all DQ crossings found, locate all next DQS crossings that cross 0V.
6 tDS is defined as the time between the DQ crossing and the DQS crossing.
7 Collect all tDS.
8 Find the worst tDS 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 the worst tDS 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 the worst tDS 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 (VREF 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.
Symbol LPDDR2 Units Specific Notes
400 333 266 200
tDS(base) 180 300 450 700 ps V
IH/L(AC)
= V
REF(AC)
+/- 300mV