HUAWEI EM770 HSPA PC Embedded Module V100R001
Product Specification
Issue 1
(2008-09-15)
Huawei Confidential: This documents is Huawei Proprietary and Confidential(NDA
Required).It may not be duplicated, neither distributed externally without
prior and written permission of Huawei.
Page
26 of 68
IO
Minimum
Maximum
V
OH
0.7Vcc
Vcc+0.3
The IO signal is bidirectional and is pulled up to VCC by a 20 k
Ω
resistor, as the
standard recommends.
Note:
This pull-up resistor should be placed near to the SIM connector and it should be connected to
the UIM PWR.
The V
OL
max of 0.45 V for the outputs 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.
4.
ESD protection
Since the SIM is a CMOS device, ESD protection devices should be placed near to
the SIM connector to provide protection. In addition, all the SIM interface signals
should be bypassed with a 33 pF capacitor.
5.
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).
6.
Routing recommendations
The SIM interface signals consist of four signals that are Vcc, RST, CLK, and IO (Vpp
is also connected but not used in many applications). Due to the relatively low clock
frequencies involved, the concern is not the degradation of the SIM signals
themselves. The main concern is 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:
l
It is recommended that these signals should be routed over a contiguous ground
plane.
l
SIM interface signals should not be routed near high transient signals (power
supply chokes and DC/DC switching FETs).
l
Avoid routing of these signals near output connectors.
l
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.
3.2.5
W_DISABLE# Signal
The W_DISABLE# signal is provided to allow users to disable wireless
communications add-in cards. When the W_DISABLE# signal is asserted, all radios
should be disabled. When the W_DISABLE# signal is not asserted, the radio may
transmit if not disabled by other means such as software.
The W_DISABLE# signal is an active low signal with internal 100 k
Ω
pull-up resistor
that shall disable radio operation when being asserted (driven low) by the system.
Due to the potential of a software disable state, the combination of the software state
and W_DISABLE# assertion state must be determined before the normal operation is
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