SLVUCU5 December 2025 UCD91160 , UCD91320
When the host (or controller) writes PMBus configuration data to the target, it does not write directly to target's flash memory. Instead, the host writes to the target's volatile memory (RAM). The target device accepts these incoming commands and maps these to an area in RAM, possibly translating the configuration data to an internal device-specific format.
Since the PMBus command writes are to RAM, engineers can safely test changes, and if there is an error, they can recover the previous configuration by issuing a device reset. When an engineer determines that the configuration is valid, they can commit the configuration to non-volatile flash memory by issuing the STORE_DEFAULT_ALL PMBus command, which handles copying parts of RAM to flash memory.