LTE Module Series
EM05 Hardware Design
EM05_Hardware_Design Confidential / Released 31 / 59
Normally Open (U)SIM Card Connector
When the (U)SIM is absent, CD is open to SW and USIM_DET is at low level.
When the (U)SIM is inserted, CD is short-circuited to SW and USIM_DET is at high level.
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
USIM_VDD
USIM_GND
USIM_RST
USIM_CLK
USIM_DATA
0R
0R
0R
100nF
(U)SIM Card Connector
GND
33pF 33pF 33pF
VCC
RST
CLK
IO
VPP
GND
GND
15K
USIM_VDD
Figure 18: Reference Circuit of a 6-Pin (U)SIM Card Connector
In order to enhance the reliability and availability of the (U)SIM card in
customers’ applications, please
follow the criteria below in (U)SIM circuit design:
Keep placement of (U)SIM card connector to the module as close as possible. Keep the trace length
as less than 200mm as possible.
Keep (U)SIM card signals away from RF and VCC traces.
Assure the ground between the module and the (U)SIM card connector short and wide. Keep the
trace width of ground and USIM_VDD no less than 0.5mm to maintain the same electric potential.
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 10pF. The 0
Ω resistors should be added in series between the
module and the (U)SIM card so as to suppress EMI spurious transmission and enhance ESD
protection. The 33pF capacitors are used for filtering interference of RF. 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.
Quectel
Confidential
