UPSD3422_06 Datasheet, PDF (170/293 Pages) STMicroelectronics – Turbo Plus Series Fast Turbo 8032 MCU with USB and Programmable Logic

USB interface
uPSD34xx
25.5
Typical connection to USB
Connecting the uPSD34xx to the USB is simple and straightforward. Figure 56 shows a
typical self-powered example requiring only three resistors and a USB power detection
circuit. The USB power detection circuit detects when the device has been connected to the
USB. When V_BUS is detected, it switches 3.3V to the pull-up resistor on the D+ line. Per the
USB specification, the pull-up resistor on D+ is required to signal to the upstream USB port
when a full speed device has been connected to the bus. The resistors in series in the D+
and D– lines are recommended per the USB specification to reduce transients on the data
lines.
Figure 56. Typical self powered example
VCC
VCC
VDD
USB
VBUS
D–
D+
GND
USB Power
Detection Block
+3.3V
1.5KΩ
22Ω
22Ω
VCC
VDD
uPSD34xx
USB–
USB+
GND
AI10495
170/293