84 MHz Cortex-M4 in a WLCSP — what this part is
The 49-WLCSP package (wafer-level chip-scale) saves board area but demands careful PCB layout — the 0.4 mm ball pitch and 0.5 mm body mean the reflow profile and stencil aperture need tuning for reliable solder joints.
Peripherals and connectivity — what is on the die
For connectivity it offers I²C, IrDA, LINbus, SDIO, SPI, UART/USART, and USB OTG — enough for a sensor hub, a motor-control node, or a USB-to-serial bridge. The 36 I/O lines are all available in the WLCSP, though some are shared with the ADC inputs; the pin mux table in the reference manual is worth a read before committing the schematic.
Temperature grade and operating range
It fits outdoor telecom enclosures, factory-floor controllers, and automotive cabin applications — but not under-hood or engine-bay environments where 125°C is required.
Sourcing posture — active, no LTB risk
The WLCSP package is less common in distributor stock than the LQFP-48 variant (STM32F401CCU6), so lead time may run a few weeks longer; plan the BOM accordingly.