Power Interface; Overview Of Operation; Em Power Signals; Electrostatic Discharge - Sierra Wireless MC5720 Hardware Integration Manual

P C I E x p r e s s M i n i C a r d H a r d wa r e I n t e g r a t i o n G u i d e

Power Interface

Overview of operation

The EM is designed to run off the same power supply as the host system
(typically 3.3V). There is neither an independent power supply within the EM
nor any protection circuits to guard against electrical issues. It is the
responsibility of the host system to provide safe and continuous power to the EM
at all times.
The EM powers on when W_Disable# is floated or driven high, and valid power
is applied to the VCC rail. Once turned on by the host system, the EM remains on
until the host commands the module to power down. Once the unit is powered
off, the host can turn the unit on again. The EM unit monitors its voltage and
informs the host if the power rail gets too low by requesting shutdown.

EM power signals

shows the signals comprising the host-EM power interface. A sample schematic
of the interface and BOM (Bill of Materials) are shown on the following page.
See the Product Specification document for your module for detailed
specifications on the power signals.

Electrostatic discharge

You are responsible for any ESD protection on digital circuits. Specific
recommendations are provided as needed for each of the interfaces described in
this guide; however, the level of protection required depends on your application.
For ESD protection level of the EM pins during your product assembly and test,
refer to the EM Product Specification.
Extra precaution should be taken on the U-SIM/R-UIM signals as these signals
are usually brought out externally and are susceptible to ESD events. ESD
protection is recommended at the point where the contacts are exposed.
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