Usb Interface; Usb Pin Definition - Fibocom NL668-LA Series Hardware Manual


USIM_CLK and USIM_DATA signals are ground isolated to avoid mutual interference. If it is difficult
to do so, (U)SIM signal needs to be ground protected as a set;

The filter capacitor and ESD device of (U)SIM card signal cable should place close to the (U)SIM
card connector.

Please select equivalent capacitor is 22pF to 33pF for ESD device.

USIM_DATA should pull up to USIM_VDD with a 10K resistor.

5.4 USB Interface

5.4.1 USB Pin Definition

NL668-LA series module support USB2.0, compatible with USB High-Speed(480Mbits/s) and USB
Full-Speed(12Mbits/s). module USB bus timing and electrical characteristics refer to Universal Serial Bus
Specification 2.0.
Table 5-9 USB pin definition
Pin name I/O
USB_DP IO
USB_DM IO
USB_VBUS PI
For more information about the USB 2.0 specification, please refer to
Note:
Since the module supports USB 2.0 High-Speed, TVS tube equivalent capacitance on the
USB_DM/DP differential signal cable is required to be less than 1pF, and a 0.5pF capacitance
TVS is recommended.
Connect a 0Ω resistor to USB_DM / DP differential line to help analyze problems.
USB_DM and USB_DP are high-speed differential signal cables, can achieve the maximum
transmission rate of 480Mbits/s, and must follow the rules below in PCB Layout:
 USB_DM and USB_DP signal cable's control differential impedance is 90Ω.

USB_DM and USB_DP signal cables shall be parallel and equal in length, and avoid the
right-angle route.

USB_DM and USB_DP signal cables are routed on the signal layer closest to the ground
layer, and the cables shall be grounded.
Reproduction forbidden without Fibocom Wireless Inc. written authorization - All Rights Reserved.
FIBOCOM NL668-LA Series Hardware Guide
Pin No.
69
70
71
Description
USB differential data bus D+
USB differential data bus D-
USB Plug detect
http://www.usb.org/home
Page 34 of 61