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L810-MiniPCIeHardware User Manual
Page 17 of 26
5.1.2 USB Interface Application
Reference circuit diagram is shown in Figure 5-1:
Figure 5-1 Reference Circuit Diagram for USB Interface
For T101 and T102, it is required to use 1pF TVS diodes or any with lower capacitance, it is
recommended to use 0.5pF TVS diodes. USB_D+ and USB_D- are high speed differential signal lines,
and the maximum transfer rate is 480Mbps, the following shall be noted in the case of PCB Layout:
USB_D+ and USB_D- signal lines should have the equal length and should be parallel, and right
angle wiring should be avoid.
USB_D+ and USB_D- signal lines should be wrapped with GND at the ends.
USB 2.0 differential signal lines should be routed on the layer that is next to the ground layer.
The impedance of differential lines should be 90 Ohm.
5.2 USIM Interface
5.2.1 Signal Description for USIM Card
Pin
Pin name
I/O
Pin description
Voltage
8
USIM_VCC
O
Power supply for external USIM card
1.8V/3V
10
USIM_IO
I/O
USIM data signal
1.8V/3V
12
USIM_CLK
O
USIM clock signal
1.8V/3V
14
USIM_RST
O
USIM reset signal
1.8V/3V
