User's Manual

COMPANY CONFIDENTIAL
33
9.1.1 Power up, Reset and Power Down Timing
Time
Voltage
NRESET_MOD
0V
+1.2V
+3.3V
< 300ms
>= 2ms
Power Up Power Down
9.2 RF Considerations
Note that overall system, RF and WiFi performance is significantly affected by the product design, environment and the
application. It is the responsibility of the product designer to ensure proper system level shielding (if required) and to verify
performance and fitness for the given product features and applications.
The WiFi performance will be affected by the RF environment surrounding the CX module. Please ensure that the CX
module is positioned in a “quiet” RF environment, as far away as possible from high frequency clock signals and any other
sources of RF energy. Also, make sure the antenna is not shielded by any metal objects, for example loudspeakers or other
metal parts. Please make sure that the power supplies, in particular the +1.9V supply, are quiet and free from noise.
SMSC recommends that systems implementing AirPlay should use a module configuration that includes on-module
shielding, as well as paying particular attention to system configuration and shielding. In particular, SMSC is recommending
the use of the Bottom Shield versions of the modules, which allows greater freedom in antenna positioning.
Also, please see the SMSC Application Note:
SMSCAppNote - CX870_Antenna_Placement_V1_4.pdf
regarding antenna positioning guidelines.
Please see below picture for the recommended keep out area and cable routing for the antennas.