Description
USB3.0 is a SuperSpeed USB protocol that can achieve maximum bandwidth of 5Gbits/s.
Microchip USB5744 IC is used as a USB3.0 hub controller. Microchip’s USB5744 IC is a 4 port, SuperSpeed (SS)/Hi-Speed (HS), low power, low pin count configurable and fully compliant with the USB 3.1 Gen 1 specification. The USB5744 also supports Full Speed (FS) and Low Speed (LS) USB signaling, offering complete coverage of all defined USB operating speeds.
The USB 3.0 is a 10 core cable.
- Two cores are D+/D- for USB2.0 data
- Two cores are SSTX+/SSTX- for USB3.2 transmitter data
- Two cores are SSRX+/SSRX- for USB3.2 receiver data
- Two cores are VCC & GND for the power
- Two cores are shield over the SSTX and SSRX lines
The USB Hub system consist of below blocks
- Upstream Port (connection with the host PC)
- Downstream port (connection with the peripherals)
- Main USB HUB controller (manages the communication between peripheral devices and the computer system)
- Overcurrent protection IC (Protect the downstream port from short circuit and overcurrnet).
- ESD protection for downstream and upstream port (To protect the circuit from ESD)
The USB5744 is a configurable IC. The superspeed TX+/Tx- lines can be swapped to simplify the routing. The vendor string can be changed using the Microchop MPLAB Windows utility.
PCB Layout
A PCB layout has to follow high speed PCB design guideline provided by Microchip while designing the PCB to maintain signal integrity and avoid EMC issues.
PCB Details
- 6 Layer Impedance controlled PCB.
- SuperSpeed trace impedance: 85 Ohm.
- D+/D- trace impedance : 90 Ohm
- Differntail pair length matching
USB Hub used on PCB
