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FM350-GL Hardware Guide
Page 30 of 59
Pin
Pin Name
I/O
Reset Value Description
Level
66
SIM_DETECT
I
PD
USIM card detect, internal 390K pull-
up.
Active high, and high level indicates
SIM card is inserted; and low level
indicates SIM card is
detached.
1.8V
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 3-16:
Figure 3-16 Reference circuit for N.C. SIM card slot
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 3-17: