256 Mbit SPI NOR flash in a 6x5 mm MLP8 package
The MT25QU256ABA1EW7-0SIT is a 256 Mbit SPI NOR flash from Micron's MT25QU family, organized as 32M x 8 bits. It runs on a 1.7 V to 2 V supply rail and clocks up to 133 MHz over the SPI bus. The 0.5 mm pitch means a 2-layer board can fan out the outer rows, but a 4-layer board gives cleaner signal routing for the SPI lines at 133 MHz.
SPI throughput and write timing for firmware updates
At 133 MHz, the SPI interface delivers a raw bit rate of 133 Mbps. The Quad I/O capability (implied by the family architecture) pushes the effective throughput to roughly 532 Mbps, but the controller must support the Quad I/O protocol and the flash's dummy-cycle configuration must match the read command. Page program time is 2.8 ms typical, and sector erase takes 8 ms typical. For a 256 Mbit device, a full-chip erase runs well over a second — budget this into the firmware update procedure. The 100,000 program/erase cycle endurance per sector means field updates are viable over the product lifetime without wear-leveling at the application layer.