In summary:
For the practicing engineer, the "Value" of this PDF lies in three specific areas: jesd794d pdf
JESD79-4D is the "Gold Standard" for DDR4. It is a mature, comprehensive document that has stabilized the industry. While the industry is transitioning to DDR5 (JESD79-5), the 79-4D document remains arguably the most important reference for the current installed base of computing hardware. In summary: For the practicing engineer, the "Value"
| Timing | Symbol | Typical Value | |--------|--------|----------------| | – Row to Column Delay | 15 ns (≈ 10 CK) | | tRP – Row Precharge | 15 ns (≈ 10 CK) | | tRAS – Row Active Time | 35 ns (≈ 24 CK) | | tRC – Row Cycle Time | 50 ns (≈ 34 CK) | | tRFC – Refresh Cycle | 350 ns (standard) | | tREFI – Refresh Interval | 7.8 µs (typ.) | | tWR – Write Recovery | 15 ns (≈ 10 CK) | | tCCD – Column‑to‑Column Delay | 4 CK (for BL8) | | tFAW – Four Activate Window | 30 ns (≈ 20 CK) | | Timing | Symbol | Typical Value |
Improves signal integrity and reduces I/O power usage compared to older signaling methods. Accessing the PDF