Normally Open (U)Sim Card Connector; U)Sim Card Connector Without Hot-Plug - Quectel RM520N-GL Hardware Design

4.1.4. Normally Open (U)SIM Card Connector

With a normally open (U)SIM card connector, CD1 and CD2 of the connector are disconnected when
there is no (U)SIM card inserted. (U)SIM card detection by low level is applicable to this type of connector.
Once (U)SIM hot-plug is enabled by executing AT+QSIMDET=1,0, a (U)SIM card insertion will drive
USIM_DET from high to low level, and the removal of it will drive USIM_DET from low to high level.
⚫
When the (U)SIM is absent, CD1 is open from CD2 and USIM_DET is at high level.
⚫
When the (U)SIM is present, CD1 is pull down to ground and USIM_DET is at low level.
The following figure shows a reference design for (U)SIM interface with a normally open (NO) (U)SIM
card connector.
Module
USIM_VDD
USIM_RST
USIM_CLK
USIM_DET
USIM_DATA
GND
NOTE: All these resistors, capacitors and TVS should be close to (U)SIM card connector in PCB layout.
Figure 16: Reference Circuit for Normally Open (U)SIM Card Connector

4.1.5. (U)SIM Card Connector Without Hot-Plug

If (U)SIM card hot-plug 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 by the following figure.
RM520N-GL_Hardware_Design
USIM_VDD
10-20k
22 Ω
22 Ω
22 Ω
10 pF 10pF 10pF
(U)SIM Card
Connector
100 nF
VCC
RST
CLK
CD1
IO
TVS array
GND
5G Module Series
VPP
CD2
4.7k
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