User's Guide

LE920A4 HW User Guide Hardware Interfaces
Doc#: 1VV0301261 USB Port
Rev. 4.7.1 Page 68 of 124 2019-11-21
USB Port
The module includes a Universal Serial Bus (USB) transceiver, which operates at USB
high-speed (480 Mbits/sec). It can also operate with USB full-speed hosts (12 Mbits/sec).
It is compliant with the USB 2.0 specification and can be used for control and data
transfers as well as for diagnostic monitoring and firmware update.
The USB port is typically the main interface between the module and OEM hardware.
NOTE:
The USB_D+ and USB_D- signals have a clock rate of 480 MHz. The signal
traces must be routed carefully. Minimize trace lengths, number of vias, and
capacitive loading. The impedance value should be as close as possible to
90 Ohms differential.
Table 25 lists the USB interface signals.
Table 25: USB Interface Signals
Signal Pad No. Usage
USB_VBUS A18
Power and cable detection for the internal USB transceiver.
Acceptable input voltage range 2.2V – 5.25V @ max 5 mA
consumption
USB_D- F19
Minus (-) line of the differential, bi-directional USB signal to/from
the peripheral device
USB D+ D19
Plus (+) line of the differential, bi-directional USB signal to/from
the peripheral device
USB_ID B19 USB ID signal supporting USB2.0 OTG (see note below)
NOTE:
USB_VBUS input power is internally used to detect the USB port and start
the enumeration process. A power supply pin with a maximum of 5 mA is
required.
Do not use pull up or a voltage divider for sourcing this supply
NOTE:
Even if USB communication is not used, it is still highly recommended to
place an optional USB connector on the application board.
At least test points of the USB signals are required since the USB physical
communication is needed in the case of SW update.