Usim Interface Circuit; Sim Card Slot - Fibocom L850-GL Series Hardware Manual

3.5.2 USIM Interface Circuit

3.5.2.1 N.C. SIM Card Slot
The reference circuit design for N.C. (Normally Closed) SIM card slot is shown in Figure 3-18:
The principles of the N.C.SIM card slot are described as follows:
When the SIM card is detached, it connects the short circuit between CD and SW pins, and drives

the SIM_DETECT pin low.
When the SIM card is inserted, it connects an open circuit between CD and SW pins, and drives the

SIM_DETECT pin high.
3.5.2.2 N.O. SIM Card Slot
The reference circuit design for N.O. (Normally Open) SIM card slot is shown in Figure 3-19:
The principles of the N.O.SIM card slot are described as follows:
When the SIM card is detached, it connects an open circuit between CD and SW pins, and drives

the SIM_DETECT pin low.
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FIBOCOM L850-GL Series Hardware Guide
Figure 3-18 Reference circuit for N.C. SIM card slot
Figure 3-19 Reference circuit for N.O. SIM card slot
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