Usb Interface - Quectel RM502Q-GL Hardware Design

If (U)SIM card detection function is not needed, please keep USIM_DET unconnected. A reference circuit
for (U)SIM card interface with a 6-pin (U)SIM card connector is illustrated in the following figure.
Module
USIM1_VDD
USIM1_RST
USIM1_CLK
USIM1_DET
USIM1_DATA
Note: All these resistors, capacitors and TVS should be close to (U)SIM card connector in PCB layout.
Figure 19: Reference Circuit of a 6-Pin (U)SIM Card Connector
In order to enhance the reliability and availability of the (U)SIM card in applications, please follow the
criteria below in (U)SIM circuit design.
⚫
Keep (U)SIM card connector as close as possible to the module. Keep the trace length as less than
200 mm as possible.
⚫
Keep (U)SIM card signal traces away from RF and VCC traces.
⚫
To avoid cross-talk between USIM_DATA and USIM_CLK, keep them away from each other and
shield them with ground surrounded.
⚫
In order to offer good ESD protection, it is recommended to add a TVS diode array with parasitic
capacitance not exceeding 10 pF. The 22 Ω resistors should be added in series between the module
and the (U)SIM card connector so as to suppress EMI spurious transmission and enhance ESD
protection. The 33 pF capacitors are used to filter out RF interference.
⚫
The pull-up resistor on USIM_DATA trace improves anti-jamming capability and should be placed
close to the (U)SIM card connector.

3.7. USB Interface

RM502Q-GL provides one integrated Universal Serial Bus (USB) interface which complies with the USB
3.1 & 2.0 specifications and supports super speed (10) on USB 3.1 and high speed (480 Mbps) and full
speed (12 Mbps) modes on USB 2.0. The USB interface is used for AT command communication, data
transmission, GNSS NMEA sentence output, software debugging, firmware upgrade and voice over
USB*.
RM502Q-GL_Hardware_Design
USIM1_VDD
36 10-20k
30 22R
22R
32
66
22R
34
GND
RM502Q-GL Hardware Design
(U)SIM Card
Connector
100 nF
VCC
RST
CLK
IO
GND
TVS
5G Module Series
VPP
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