JEDEC JESD406-5 PDF

This publication describes the serial presence detect (SPD) values for all LPDDR5/5X memory modules. In this context, “modules” applies to memory modules like traditional Dual In-line Memory Modules (DIMMs) or solder-down motherboard applications. The SPD data provides critical information about all modules on the memory channel and is intended to be use by the system's BIOS in order to properly initialize and optimize the system memory channels. The storage capacity of the SPD non-volatile memory is limited, so a number of techniques are employed to optimize the use of these bytes, including overlays and run length limited coding.

All unused entries will be coded as 0x00. All unused bits in defined bytes will be coded as 0 except where noted.

Timing parameters in the SPD represent the operation of the module including all DRAMs and are valid from tCKAVGmin to tCKAVGmax (see SPD bytes 18, 19, 124, and 125).

To allow for maximum flexibility as devices evolve, SPD fields described in this document may support device configuration and timing options that are not included in the JEDEC LPDDR5/5X SDRAM standard (JESD209-5). Please refer to DRAM supplier data sheets or JESD209-5 to determine the compatibility of components.