The S25FL256LDPMFV000: 256 Mbit density, organized as 32M x 8, with SPI Quad I/O interface at 66 MHz.
66 MHz Quad I/O — read throughput and pin count trade-off
The 66 MHz clock rate with Quad I/O delivers a sustained read throughput that keeps most Cortex-M and RISC-V cores fed for execute-in-place (XIP) boot without needing a parallel NOR interface. Compared to single-SPI, Quad I/O quadruples the data rate per pin, which matters when the PCB layout is tight and you want to avoid a high-pin-count package. The QPI mode further reduces command overhead for random reads, improving the average latency in code-shadowing applications.