U3
FT232RL
IC
SSOP-28
USB-serial bridge
About this component
Presents a virtual COM port to the computer and passes serial data to the ATmega328P's UART; its DTR line pulses the MCU's reset so sketches can be uploaded without pressing the button. On the Nano it also supplies the small 3.3 V output on the 3V3 header pin, so that pin is dead if this chip has failed. A Nano that powers up but is not seen by the computer usually points to this chip, the USB connector or the USB fuse/diode. Part variants: Genuine Arduino/Gravitech Nano boards use the FTDI FT232RL. The WCH CH340G is found on many third-party clones, not on the official board.
What it does on this board
Converts USB to the serial lines used to program the MCU.
Pinout & readings
No pinout or reference readings yet — these show what each pin does and what a healthy part should measure.