Design Guide

Intel Pro/Wireless 2100/2100A – Bluetooth Coexistence Interface Design Requirements
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276 Intel
®
855GM/855GME Chipset Platform Design Guide
Figure 148. Recommended Topology for Coexistence Traces
Intel®
PRO/Wireless
2100/2100A
14.2. DC Power Requirements for Bluetooth
The Bluetooth* module requires a 3.3-V power supply that can be regulated within a tolerance of ±2%.
This source may be derived from any power rail available on the platform.
14.3. Start Up Conditions and Logic Protection
It is assumed that the power on/off and initialization of the Bluetooth module and Intel PRO/Wireless
2100/2100A are asynchronous and the power delivery to each device is not coupled. As a result,
concerns arise as to the logic state of the coexistence lines when the module intended to receive a signal
is not powered up. This could possibly cause damage to either the Bluetooth* module or Intel
PRO/Wireless 2100/2100A and/or place one of the components into an indeterminate state.
A recommended implementation that will protect both components from potential damage caused by
asynchronous power on/off is depicted in Figure 148. For the Bluetooth module, it is recommended that
a tri-state buffer (powered by the Bluetooth* module supply) and a 1-kΩ series resistor be placed near
the Bluetooth module. Likewise, a tri-state buffer (powered by the mini-PCI 3.3V supply) should be
placed near to the Intel PRO/Wireless 2100/2100A module. This low cost solution has been validated
and noted to have a minimal impact on board area if implemented as recommended.
The RS - Banias Coexistence System Specification requires that no logic “high” signals be asserted by
the Bluetooth module on the coexistence signal lines until the Intel PRO/Wireless 2100/2100A has
signaled to the Bluetooth module that it is ready. It is assumed that the Bluetooth module will initialize
upon power up of the platform and that during this period (estimated to be < 15 ms) the Bluetooth
module’s GPIOs will default to either inputs or a high impedance state. Since the logic level of the Intel
PRO/Wireless 2100/2100A coexistence signals is not known during this time, it is important that no
logic “high” signal be asserted by the Bluetooth* module on either of the coexistence signal lines. Such
signals could cause damage or entry into an indeterminate state if the Intel PRO/Wireless 2100/2100A is
not ready to accept them. It is also possible that the Bluetooth module could assert a logic high signal
when the Intel PRO/Wireless 2100/2100A is powered down since the power sources for the modules are
not coupled.