Quectel EG915U-EU - Page 45

LTE Standard Module Series
EG915U-EU_Hardware_Design 44 / 81
The following figure shows a reference design for (U)SIM interface with an 8-pin (U)SIM card connector.
Module
USIM_VDD
GND
USIM_RST
USIM_CLK
USIM_DATA
USIM_DET
0R
0R
0R
VDD_EXT
51K
100 nF
GND
GND
33 pF 33 pF 33 pF
VCC
RST
CLK
IO
VPP
GND
GND
USIM_VDD
15K
(U)SIM Card Connector
Switch
Figure 20: Reference Circuit of (U)SIM Interface with an 8-Pin (U)SIM Card Connector
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
GND
USIM_RST
USIM_CLK
USIM_DATA
0R
0R
0R
100 nF
GND
33 pF 33 pF
33 pF
VCC
RST
CLK IO
VPP
GND
GND
15K
USIM_VDD
(U)SIM Card Connector
Figure 21: 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 placement of (U)SIM card connector as close to the module as possible. Keep the trace length
less than 200 mm as far as possible.
⚫ Keep (U)SIM card signals away from RF and VBAT traces.
⚫ Ensure USIM_VDD has a bypass capacitor less than 1 µF, and the capacitor should be close to the
(U)SIM card connector.