Usb Interface - Quectel EG91 Series Hardware Design

the trace width of ground and USIM_VDD no less than 0.5mm to maintain the same electric potential.
Make sure the bypass capacitor between USIM_VDD and USIM_GND less than 1uF, and place it as
close to (U)SIM card connector as possible. If the ground is complete on customers' PCB, USIM_GND
can be connected to PCB ground directly.
 To avoid cross-talk between USIM_DATA and USIM_CLK, keep them away from each other and shield
them with surrounded ground.
 In order to offer good ESD protection, it is recommended to add a TVS diode array whose parasitic
capacitance should not be more than 15pF. The 0Ω resistors should be added in series between the
module and the (U)SIM card to facilitate debugging. The 33pF capacitors are used for filtering
interference of EGSM900. Please note that the (U)SIM peripheral circuit should be close to the (U)SIM
card connector.
 The pull-up resistor on USIM_DATA line can improve anti-jamming capability when long layout trace
and sensitive occasion are applied, and should be placed close to the (U)SIM card connector.

NOTE
"*" means under development.

3.10. USB Interface

EG91 contains one integrated Universal Serial Bus (USB) interface which complies with the USB 2.0
specification and supports high-speed (480Mbps) and full-speed (12Mbps) modes. The USB interface is
used for AT command communication, data transmission, GNSS NMEA sentences output, software
debugging, firmware upgrade and voice over USB*. The following table shows the pin definition of USB
interface.
Table 10: Pin Definition of USB Interface
Pin Name Pin No.
USB_DP 9
USB_DM 10
USB_VBUS 8
GND 3
For more details about USB 2.0 specifications, please visit http://www.usb.org/home.
EG91_Hardware_Design
I/O Description
IO USB differential data bus (+)
IO USB differential data bus (-)
PI USB connection detection
Ground
LTE Standard Module Series
EG91 Hardware Design
Comment
Require differential
impedance of 90Ω.
Require differential
impedance of 90Ω.
Typical: 5.0V
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