2Mbit SPI flash with 70 MHz read — code shadow or data log
The Renesas AT45DB021E-SHN2B-T is a 2Mbit SPI serial flash organized as 1024 pages of 256 bytes each, clocked at up to 70 MHz over the SPI bus. That page structure maps cleanly to firmware shadowing — the MCU boots by copying the first page into SRAM, then the remaining pages stream in at 70 MHz, keeping the boot time under the watchdog timeout on most Cortex-M designs.
Industrial temperature and write-cycle budget
Page write time is 8µs typical, with a 3ms page erase — for a data logger writing one 256-byte record every minute, the write cycle takes 8µs and the erase happens on a separate cycle. The 2Mbit density holds roughly 8000 such records before wrap-around, so wear-leveling in firmware is optional for low-frequency logging but recommended for sustained writes.