Fibocom L831-EAU-01 - USB2.0 Interface Application; USIM Interface; USIM Pins Description

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L831-EAU-01 Hardware User Manual Page
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3.4.2 USB2.0 Interface Application
The reference circuit is shown in Figure 3-14:
Figure3- 14 Reference Circuit for USB 2.0 Interface
Since the module supports USB 2.0 High-Speed, it is required to use TVS diodes with equivalent
capacitance of 1pF or smaller ones on the USB_D-/D+ differential signal lines, it is recommended to use
0.5pF TVS diodes.
USB_D- and USB_D+ are high speed differential signal lines with the maximum transfer rate of 480 Mbit/s,
so the following rules shall be followed carefully in the case of PCB layout:
 USB_D- and USB_D+ signal lines should have the differential impedance of 90 ohms.

USB_D- and USB_D+ signal lines should be parallel and have the equal length, the right angle
routing should be avoided.
 USB_D- and USB_D+ signal lines should be routed on the layer that is adjacent to the ground
layer, and wrapped with GND vertically and horizontally.
3.5 USIM Interface
The L831-EAU module has a built-in USIM card interface, which supports 1.8V and 3V SIM cards.
3.5.1 USIM Pins
The USIM pins description as shown in the following table:
Pin
Pin Name
I/O
Reset Value
Description
Type
36
UIM_PWR
PO
USIM power supply
1.8V/3V
30
UIM_RESET
O
L
USIM reset
1.8V/3V
32
UIM_CLK
O
L
USIM clock
1.8V/3V