Teledyne LeCroy QPHY-DDR4 - Manual (Page 43)

QPHY-DDR4 Software Option
Electrical Tests (CKdiff-DQSdiff-DQse)
The electrical tests will be discussed in 4 groups in this section. The groups of tests that are run are:
Electrical Tests on W bursts
1. SRIN_dIVW, Input Slew Rate
2. tDVAC, Time Above AC Level
3. AC Overshoot/Undershoot
Electrical Tests on R bursts
4. SRQ, Output Slew Rate
Each of these tests are described in detail below.
SRIN_dIVW, Input Slew Rate
The purpose of these tests are to characterize the slew rate on all of the W (input) signals. This test is
performed on both rising and falling edges. By default the slew rate is measured on DQ, DQS, and CK;
however, the Input Slew Rate variable allows the user to choose what signals are measured as part of
this test (see the QPHY-DDR4 Variables section for more information).
Note: The DDR4 spec introduces a different slew rate definition for DQ (SRIN_dIVW) compared to
the traditional DDR slew rate methodology (Vref to VIH(ac)/VIL(ac)). DQS and CK are both still
measured using the traditional DDR slew rate methodology. Both approaches will be described in
different sections below. The measurement methodology will only be discussed for the rising edge.
SRIN_dIVW, Input Slew Rate (DQ)
The DDR4 specification defines different voltage levels to measure the slew rate over compared to the
traditional approach of Vref to VIH(ac)/VIL(ac). The slew rate is measured across VdIVW, the input
compliance mask voltage, centered at Vref.
924291 Rev A 43