USB Application Notes TA0357 & AN4875

TA0357: Overview of USB Type C and Power Deliver Tech.
- 2 Configuration channels (CC) for the discovery, configuration and management of USB Type C Power delivery features
- A sink must assert Rd pull-down resistors on both CC pins
- USB 2.0: Nominal voltage of 5V, max current of 500mA
AN4878: Introduction to USB hardware and PCB Guidelines for STM32
- Protection against ESD and EMI:
  - The "HBM" require that USB pins of component device be tolerant p to 2kV of discharge
  - Low Price: USBLC6-2SC6 (+ ESDA7P60-1U1M for VBUS)
  - Low Area: USBLC6-2P6 ((+ ESDA7P60-1U1M for VBUS)
- VBUS Sensing:
  - A USB device must have VBUS sensing detection based on the USB specification
  - When the device detects the host's presence it connects its pull-up resistor to either a D+ or D- data signal line, this allows the host to detect the device presence on the bus
  - 1) If the USB device is bus powered, USB sensing isn't mandatory (USB is always connected with device is powered)
  - 2) Device is self powered - VBUS sensing is mandatory
  - ************* Not all STM32 microcontrollers that have USB peripherals have dedicated sensing pins
    - If they do, it is usually - PA9 additional functions: OTG_FS_VBUS
  - ************* The embedded pull up resistor on D+ pin in STM32G0B1CE is used for USB device detection

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