Windless handheld mini fan

Design Purpose:
To combat the summer heat, this small desktop fan can be used to cool a laptop or blow air directly on the user. It has a built-in battery for outdoor use.
Design Scheme:
Overall Design Scheme, Functional Block Diagram,
Schematic Diagram, Design Description:
Battery Management:
A CN3763 is used to charge three lithium batteries. Battery balancing protection uses a BM3451UNDC-T28A.
A DC interface (12~24V) is used to charge the CN3763, and a CH224K is used to induce 15V for charging the CN3763 via a TYPE-C port.
Power Management:
An SI2301 is used to control the microcontroller's power supply. Automatic power-on upon button press. Automatic power-off upon timer completion. Fan
Speed ​​Management:
PWM+PMOS is used to control the fan speed. A button switches between high, medium, and low fan speeds.
Timer Shutdown:
A microcontroller timer manages the timer shutdown function. Each press of the timer button increases the duration by 30 minutes.
Product Demonstration: Actual
product images.
Notes
: The fan is barely perceptible; please do not attempt to replicate this design!