Sierra Wireless AirPrime SL808 Series, Product Technical Specification & Customer Design Manuallines, Page: 43 / 122

Rev 1 Dec.10 Proprietary and Confidential - Specifications subject to change 43
4.6.1 SIM pin descriptions
Table 4-10 describes the SIM interface pins.
See Digital I/O electrical information on page 39 for 1V8 voltage characteristics
and reset state definitions.
Note: To reduce crosstalk from clock to SIM data line, it is recommended to have 18pF on
the EXT_USIM_CLK for the eSIM-installed model of SL, and 36pF for modules without
eSIMs.
4.6.2 Application notes
See Reference schematic on page 40 for an implementation of the SIM interface.
4.6.2.1 SIM socket pin description
Table 4-11 describes the required SIM socket pins.
Table 4-10: USIM interface signals
Pin Name I/O
Type
Reset
state
a
Description Notes
6 EXT_VREG_USIM USIM power supply
•
1.8 V (3G) or 3 V (2G).
•
Maximum allowed current draw =
10 mA.
7 EXT_USIM_RESET USIM reset signal
8 EXT_USIM_DATA USIM data
•
Requires 15–25 k

pull-up resistor
to EXT_VREG_USIM.
•
Shunt capacitor in pF range may be
needed (PCB provision for
capacitor is recommended)
9 EXT_USIM_CLK USIM clock
•
Typically 4 MHz at
EXT_VREG_USIM level.
•
Host should minimize rise time (<
50 ns) by adjusting trace capaci-
tance and filtering needs as
required
a. See Table 4-4 on page 40 for state definitions.
Table 4-11: SIM socket pin descriptions
Pin Signal Description
1
VCC EXT_VREG_USIM
2
RST EXT_USIM_RESET