Tait TB8100 Service Manual page 210

Standby Power
Supply
Auxiliary Power
Supply
Interface to AC
Module
210 Power Management Unit Circuit Description
The battery input voltage is also provided as a digital signal to the
microprocessor via opto-coupler circuitry. This provides isolation between
battery ground and microprocessor ground.
The battery control circuitry also prevents deep discharge of the battery by
removing the load from the battery if the voltage falls below a minimum
threshold. This threshold is independent of the microprocessor threshold,
which is set by the user with the Service Kit.
Another function of the battery control circuitry is to provide the
microprocessor with information to identify which DC module is fitted to
the PMU (i.e. 12V, 24V or 48V).
The battery control circuitry is located on a separate card which plugs into
the DC converter board.
The standby power supply is a high efficiency, low power DC converter
which operates in parallel with the main DC converter.
This converter provides a low power output to the reciter, and can also
operate when the main DC converter is shut down (i.e. deep sleep mode).
It is protected from overload and short circuit.
The circuitry for the standby power supply is located on a separate card
which plugs into the DC converter board.
The optional auxiliary power supply uses a high power version of the circuit
design used in the standby power supply. It operates from the high current
28VDC output from the AC converter or DC converter (depending on
which is operating). The auxiliary power supply converter is voltage and
current regulated. The mode of operation is controlled with the Service
Kit.
The circuitry for the auxiliary power supply is located on a separate board
which is mounted on the heatsink of the DC module. The board is
connected to the AC converter board via an 8-way cable.
The main function of this power supply is to provide a controlled
13.65VDC, 27.3VDC or 54.6VDC output (depending on model), as the
main output for the TB8100 base station is 28VDC.
This interface consists of the connectors which connect the DC module to
the AC module. Although there is no circuitry involved this interface, it is
included in the block diagram to illustrate the interconnection between the
DC and AC modules.
TB8100 Service Manual
© Tait Electronics Limited September 2006