133 MHz Quad SPI — throughput for boot and logging
The 133 MHz clock frequency on the Quad I/O interface gives a theoretical read throughput of 532 Mbps. That matters when the MCU boots from external Flash or when the system logs telemetry without stalling the core. The QPI mode reduces the command overhead by using the four I/O lines for both address and data, which tightens the bus turnaround. On page 7 of the datasheet you will find the AC timing table — the nominal 133 MHz is at 2.7 V minimum, so the timing closure holds across the full supply range.
It is a surface-mount device, so the standard SOIC-16 footprint applies. The wide body gives enough room for the eight SPI and control signals plus the supply and ground pins.