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LTE Module Series
EC21 Hardware Design
EC21_Hardware_Design Confidential / Released 40 / 94
EC21 supports USIM card hot-plug via the USIM_PRESENCE pin. The function supports low level and
high level detections, and is disabled by default. Please refer to
document [2]
about
AT+QSIMDET
command for details.
The following figure shows a reference design for USIM card interface with an 8-pin USIM card connector.
Module
USIM_VDD
USIM_GND
USIM_RST
USIM_CLK
USIM_DATA
USIM_PRESENCE
22R
22R
22R
VDD_EXT
51K
100nF
USIM Card Connector
GND
GND
33pF
33pF 33pF
VCC
RST
CLK
IO
VPP
GND
GND
USIM_VDD
15K
Figure 17: Reference Circuit of USIM Card Interface with an 8-Pin USIM Card Connector
If USIM card detection function is not needed, please keep USIM_PRESENCE unconnected. A reference
circuit for USIM card interface with a 6-pin USIM card connector is illustrated in the following figure.
Module
USIM_VDD
USIM_GND
USIM_RST
USIM_CLK
USIM_DATA
22R
22R
22R
100nF
USIM Card Connector
GND
33pF
33pF 33pF
VCC
RST
CLK
IO
VPP
GND
GND
15K
USIM_VDD
Figure 18: Reference Circuit of USIM Card Interface with a 6-Pin USIM Card Connector
Quectel
Confidential