Rainbow Electronics DAB-WLS-C01 (WiFi) - Manual (Page 15)

DSH_WISMC01_1v2 WISM 40 pin TCP-IP Data Sheet.doc © 2007 EZURiO Ltd
Page 15
The module should not be located in a sealed metal enclosure, as this will act as a Faraday cage and
severely attenuate the radio signal.
The antenna finish may tarnish as a result of environmental conditions and handling. This is a cosmetic
effect and does not affect the RF performance.
9.2 External Antenna
The approval of the module was performed using a 3dBi external antenna from RF Castle Electronics
( www.rfcastle.com/pdf/RF-3dbi%20DipoleA.pdf ). The antenna was connected using a short cable to
convert from the U.FL connector on the module to a reverse SMA. The conditions of approval allow the
use of an alternative antenna, but require that the resulting effective radiated power does not exceed
that exhibited during the approvals testing.
To ensure that the approval is not affected, the TOTAL GAIN of the external antenna, including
insertion loss of the connectors and cable must be less than 3dBi. If a higher gain is employed, then
the pre-approved status of the module will be lost. Customers must also ensure that the frequency
characteristic of their antenna matches that of the antenna used for approval. As antennae are tuned
for their frequency band the use of a different antenna technology may result in a change in emissions
outside the 2.4GHz band. It is the customer’s responsibility to ensure that an external antenna does
not negate the approval.
U.FL connectors are supplied from a number of connector manufacturers. Details of Hirose’s mating
U.FL connectors are available at http://www.hirose.co.jp/cataloge_hp/e32119372.pdf
9.3 Power Supply Considerations
The power supply for the Module must be a single voltage source within the range of 3.3 V to 5.0 V. It
must be able to provide sufficient current for a transmit burst. This can rise to 550mA.
The Module includes on-board regulators to provide local 3.0V. This rail is accessible on pin 27 for
monitoring purposes only. Under no circumstances should this pin be used to source current.
Power (VCC_5V) is provided via the board-to-board connector Pins 28, 29 and 31. All VCC_5V and GND
pins should be connected to ensure that individual pin current capacities are not exceeded during
transmit current peaks.
9.4 Power-On-Reset
The Module is provided with an active high reset pin (Hirose 40way DF12C connector pin 13).
However, on the application of power, the Power On Reset circuit built into the Module will ensure that
the unit starts correctly. The external reset signal allows the module to be reset under software control
from the host. After a power on or reset operation, the module will de-assert the UART_RTS output and
re-assert it when it is ready to receive commands.
9.5 Operational Temperature
The Wireless LAN module is designed to meet an operational temperature of -40°C to +85°C in normal
operation where it is running in IEEE power save mode.
If the module is run in a mode that results in more frequent receive and transmit activity the operating
temperature will need to be derated to ensure that overall module power dissipation limits are not
exceeded. When the ambient temperature rises above 60°C the module should only be operated in
powersave mode 1 or higher.
The Wireless LAN module can operate in temperatures as low as -40°C, but the cold start minimum
temperature must not be below -25°C.