TB8100 Installation and Operation Manual Functional Description 49
© Tait Electronics Limited June 2005
4.4 Power Distribution
This section details how the input power feed is distributed throughout the
base station system to power its various sub-systems. The high level block
diagrams in Figure 4.5 on page 50 show the power distribution paths in
single and dual base station systems, while Figure 4.9 on page 67 provides
more detailed information on a typical single base station system. Also refer
to “Circuit Description” on page 15 for more detailed circuit descriptions
of the individual sub-systems that make up the BSS.
The TB8100 can receive input power from either the AC or DC input.
Internal seamless switching between the AC or DC input ensures there are
no power interruptions should a changeover occur between the two inputs.
The base station will default to the AC input if both AC and DC inputs are
provided.
The AC converter has a series switch which isolates the mains input from
the converter. The DC input, however, has much higher current ratings,
and supports an on/off switch on the converter only.
The outputs from both the AC and DC high power converters are added
together and fed to the PA via the PA1 and PA2 outputs. The auxiliary
output is also tapped off this summed output.
When a DC module is fitted, a high efficiency standby card can be used to
power up the receiver circuitry. If required, the high power but low
efficiency converters can then be disabled, saving considerable power during
periods of no channel activity, by using the standby card to power the reciter
more efficiently.
Base stations fitted with a 12V PA do not require a PMU. In this case the
DC input is connected directly to the PA, where it is fed to the internal
boost regulator board. This board provides a 12VDC output for the reciter
and a 28VDC output for the PA circuit boards.
The reciter input power feed is distributed to all internal reciter boards.
Local regulation ensures that noise and common mode interface signals are
kept to a minimum between sub-assemblies. Various power supplies in the
reciter further power and isolate critical sub-sections.
The reciter also powers the control panel, via a backpower protection diode.
The system control bus is used to route power to the control panel, thus
whenever a reciter is powered, and plugged into the control bus, if a control
panel is connected there will always be a reciter present to drive the control
bus functions.
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