Quectel EC21-A User Manual

LTE Standard Module Series
EC21_Series_Hardware_Design
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EC21 series supports (U)SIM card hot-plug via the USIM_PRESENCE pin. The function supports low
level and high level detections. By default, it is disabled, and can be configured via AT+QSIMDET. See
document [2] for more details about the command.
The following figure shows a reference design for (U)SIM interface with an 8-pin (U)SIM card connector.
Module
USIM_VDD
USIM_GND
USIM_RST
USIM_CLK
USIM_DATA
USIM_PRESENCE
0R
0R
0R
VDD_EXT
51K
100 nF (U)SIM Card Connector
GND
GND
33 pF 33 pF 33 pF
VCC
RST
CLK
IO
VPP
GND
GND
USIM_VDD
15K
Figure 17: Reference Circuit of (U)SIM Interface with an 8-pin (U)SIM Card Connector
If (U)SIM card detection function is not needed, keep USIM_PRESENCE unconnected. A reference
circuit for (U)SIM interface with a 6-pin (U)SIM card connector is illustrated in the following figure.
USIM_GND 10 Specified ground for (U)SIM card

Quectel EC21-A Specifications

General

Brand	Quectel
Model	EC21-A
Category	Control Unit
Language	English