User's Manual

Reproduction forbidden without Fibocom Wireless Inc. written authorization - All Rights Reserved.
L850-GL Hardware User Manual Page
32
of
51
Pin
Pin Name
I/O
Reset Value
Description
Type
30
UIM_RESET
O
L
USIM reset
1.8V/3V
32
UIM_CLK
O
L
USIM clock
1.8V/3V
34
UIM_DATA
I/O
L
USIM data,internal pull up(4.7KΩ)
1.8V/3V
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
3.6.2 USIM Interface Circuit
3.6.2.1 N.C. SIMCard Slot
The reference circuit design for N.C. (Normally Closed)SIM card slot is shown in Figure 3-12:
Figure 3-12Reference Circuit for N.C. SIM Card Slot
The principlesof theN.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.
3.6.2.2 N.O. SIM Card Slot
The reference circuit design for N.O. (Normally Open) SIM card slot is shown in Figure 3-13: