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HUAWEI EM820W HSPA+ PC Embedded Module
Hardware Guide Description of the Application Interfaces
Issue 01 (2010-12-31)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
13
Table 3-8 SIM IO requirements
IO Minimum Maximum
V
IL
0 0.4
V
IH
0.7Vcc Vcc
V
OL
–0.3 0.2 Vcc
V
OH
0.7 Vcc Vcc+0.3
The V
OL
max of 0.45 V for the output is specified at an output current of 3 mA whereas the
V
IL
max of 0.4 V for the SIM IO input is specified at an input current of 1 mA. With the smaller
current drive, the output voltage would be driven lower than the stated maximum value.
z
ESD protection
Since the SIM is a CMOS device, ESD protection devices should be placed near
the SIM connector to provide protection before connecting to the module. In
addition, all the SIM interface signals should be bypassed with a 10 pF capacitor.
The used ESD device (PESD3V3L5UY, NXP) in
Figure 3-2 is a low capacitance
5-fold ESD protection diode arrays in SOT363 package.
z
Clock frequency
The
SIM must support clock frequencies between 1 MHz and 4 MHz. (The Mini
Card can be programmed to generate a clock of 1.625 MHz, 2.6 MHz, or 3.25
MHz.)
z
Routing recommendations
The SIM interface signals consist of four signals that are UIM_PWR, UIM_RST,
UIM_CLK, and UIM_DATA (UIM_Vpp is neither connected nor used in many
applications). Due to the relatively low clock frequencies involved, the concern is
not the degradation of the SIM signals but that of routing of the SIM interface
signals through areas considered to be of high risk for RF noise coupling
(crosstalk and RF contamination), which can desensitize the radio circuitry. The
general guidelines that should be followed are listed as follows:
− It is recommended that these signals should be routed over a continuous
ground plane.
− SIM interface signals should not be routed near high transient signals (power
supply chokes and DC/DC switching FETs).
− Prevent routing of these signals near output connectors.
− Keep SIM interface signals isolated from other signals. 2x width spacing (1.5x
min) between SIM interface signals and all other signal routing is
recommended.
3.6.3 Certification Test
Using test equipment simulates a (U)SIM card to test U(SIM) protocol in GCF or
PTCRB test, If some test. If you encounter some issues during SIM/USIM test,
please contact Huawei for more details.