Service Guide

LTE-A Module Series
EM060K-GL&EM120K-GL_Hardware_Design 38 / 78
4.1.6. (U)SIM2 Card Connector
The module provides two (U)SIM interfaces. (U)SIM1 interface is used for external (U)SIM card only, and
(U)SIM2 interface is used for external (U)SIM card or internal eSIM card.
It should be noted that when the (U)SIM2 interface is used for an external (U)SIM card, the circuits are the
same as those of (U)SIM1 interface. When the (U)SIM2 interface is used for the internal eSIM card, pins
40, 42, 44, 46 and 48 of the module must be kept open.
A recommended compatible design for the (U)SIM2 interface is shown below.
Module (U)SIM Card
Connector
USIM2_DET
USIM2_DATA
USIM2_CLK
RST
CLK
CD
IO
USIM2_VDD
USIM2_VDD
USIM2_RST
VCC
GND
VPP
GND
TVS array
Note: The five 0 Ω resistors must be close to M.2 socket connector, and all other components should be close
to (U)SIM card connector in PCB layout.
48
46
44
40
42
10-20K
22 Ω
22 Ω
22 Ω
33 pF
33 pF
33 pF
100 nF
0 Ω
0 Ω
0 Ω
0 Ω
0 Ω
eSIM
Figure 17: Recommended Compatible Design for (U)SIM2 Interface
4.1.7. (U)SIM Design Notices
To enhance the reliability and availability of the (U)SIM card in applications, please follow the criteria
below in (U)SIM circuit design.
 Place the (U)SIM card connector as close to the module as possible. Keep the trace length less than
200 mm.
 Keep (U)SIM card signals away from RF and VCC traces.
 Ensure the ground between the module and the (U)SIM card connector is short and wide. Keep the
trace width of ground and USIM_VDD no less than 0.5 mm 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.
 To offer better ESD protection, add a TVS array of which the parasitic capacitance should be not
higher than 10 pF. Add 22 Ω resistors in series between the module and the (U)SIM card connector
to suppress EMI such as spurious transmission. The 33 pF capacitors are used to filter out RF
interference. Additionally, keep the (U)SIM peripheral circuit close to the (U)SIM card connector.
 For USIM_DATA, a 10–20 kΩ pull-up resistor must be added near the (U)SIM card connector.