Fibocom L831-EAU-01 - USIM Interface Circuit; N.C. SIM Card Slot

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L831-EAU-01 Hardware User Manual Page
25
of
39
Pin
Pin Name
I/O
Reset Value
Description
Type
34
UIM_DATA
I/O
L
USIM data,internal pull up(4.7KΩ)
1.8V/3V
66
SIM_DETECT
I
USIM detect, pull up(100KΩ)
Active high, and high level indicates
SIM card is inserted; and low level
indicates SIM card is detached
1.8V
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 3-15:
Figure 3-12 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.
Note:
SIM_DETECT pull-up is 100K.