Part Number: AM625
We tested the DDR4 waveforms using a TELEDYNE LECROY oscilloscope and found several items that did not pass. We would like to confirm the debugging approach with you.
Failed Items
1. Measurement: srr1, min
- Description: Input Slew Rate over VdIVW, rising edges, min (DQ)
- Current Value: 399 MV/s
- Test Criteria: x >= 1.000 GV/s
- Result: FAILED
2. Measurement: srf1, min
- Description: Input Slew Rate over VdIVW, falling edges, min (DQ)
- Current Value: 232 MV/s
- Test Criteria: x >= 1.000 GV/s
- Result: FAILED
3. Measurement: ADOS1, Max (DQ)
- Description: Maximum overshoot area per 1 UI between VDDQ and VDOS (DQ)
- Current Value: 357.31 pVs
- Test Criteria: x <= 105.00 pVs
- Result: FAILED
4. Measurement: SRQse, max
- Description: Single ended output slew rate (DQ), max
- Current Value: 10.861 GV/s
- Test Criteria: x <= 9.000 GV/s
- Result: FAILED
5. Measurement: tHZ(DQS) Max
- Description: DQS_t and DQS_c [or DQSdiff] high-impedance time, Max
- Current Value: 610.2 ps
- Test Criteria: x <= 225.0 ps
- Result: FAILED
6. Measurement: TdIPW min
- Description: DQ input pulse width, Min
- Current Value: 497.6 mUI
- Test Criteria: x >= 580.0 mUI
- Result: FAILED
Observation
It appears that the lowest point of the DDR waveform is relatively high, at over 500 mV, which is causing the above issues.
Request
We need your support to determine how to tune these parameters to meet the waveform requirements. Preferably, we would like to resolve this through software adjustments.
