Design Checklist - Sierra Wireless MC5725 Hardware Integration Manual

7: Design Checklist

Table 7-1: Hardware integration design considerations
Suggestion
Component placement
Protect the USIM socket so that the USIM cannot be removed
while the host is powered up.
If an ESD suppressor is not used, allow space on the USIM
connector for series resistors in layout (up to 100 Ω may be used
depending on ESD testing requirements).
Minimize RF cable losses as these affect the performance values
listed in the product specification document.
Antennas
Match the module / antenna coax connections to 50 Ω —
mismatched antenna impedance and cable loss negatively
affects RF performance.
If installing both the MC57xx and MC87xx in the same device,
consider using separate antennas for maximum performance.
Power
Limit host power rail dips caused by module inrush current by
adding sufficient capacitance to the host power rail.
Make sure the power supply can handle the maximum current
specified for the module type.
Limit the total impedance of VCC and GND connections to the
USIM at the connector to less than 1 Ω (including any trace
impedance and lumped element components — inductors,
filters, etc.). All other lines must have a trace impedance less
than 2 Ω.
Rev 1.9.1 Feb.09
In the event of a discrepancy in values between this guide and the Product Specification Document (PSD), the PSD takes precedence.
This chapter provides a summary of the design considerations
mentioned throughout this guide. This includes items relating
to the power interface, RF integration, thermal considerations,
cabling issues, and so on.
Note: This is NOT an exhaustive list of design considerations. It is
expected that you will employ good design practices and engineering
principles in your integration.
Proprietary and Confidential
Section where discussed
USIM operation
page 67
USIM operation
page 67
RF connection
page 39
RF connection
page 39
Antenna and cabling
page 40
Inrush currents
page 24
Current consumption overview
page 27
USIM operation
page 67
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