Chapter 2 Theory Of Operation; System Overview; Power Distribution - Motorola APX 7500 Detailed Service Manual

Chapter 2 Theory of Operation

2.1

System Overview

The APX Consolette consists of several key components: the Mainboard, the O5 control head, the
APX mobile radio and a power supply. The O5 control head provides part of the user interface for the
APX Consolette radio system. The control head provides this interface with a 320 x 83 pixel display,
five programmable menu buttons, one programmable button that defaults to emergency operation,
volume knob, mode knob, dim button, home button, power button, and navigation pad. The GCAI is
also located on the control head and allows attachment of accessories such as the microphone and
programming cables. Additional user interface is provided by the front panel keypad which consists
of twelve alpha-numeric keys as well as three function keys and a speaker mute key, an additional
LCD with three programmable buttons, a power indication LED and another mobile microphone port
that allows for programming and keyloading of the radio transceiver inside the Consolette.
2.2

Power Distribution

The Consolette contains a power supply that converts either an AC input or a DC input into two DC
outputs. The first DC output is the Main output which provides A+ (13.2VDC +/- 2%) to the mobile
transceiver and supports up to 12A continuous current. The second DC output is the Auxiliary
output, which provides A+ to both the Mainboard and O5 Control Head (via the Mainboard) and can
support up to 5A continuous current. A+ is supplied to the Mainboard from connector P2 pin 1
through 2A fuse F100. A+ is also supplied to the O5 control head via the Mainboard from connector
P2 pin 1 through inductor L101 and 4A fuse F101 before reaching connector P10 pin 4, where the
O5 power cable is attached. The Auxiliary output also provides an AC power valid indicator to the
Mainboard in the form of signal AC_POWER_GOOD through P2 pin 2 with logic High at 3.0VDC +/-
0.2, logic Low at -0.3VDC to +0.5VDC. This AC_POWER_GOOD signal is routed to two locations via
the Mainboard. The first location being the GCAI board (PPLN7790) which contains the front panel
power-on LED. AC_POWER_GOOD is routed to this board through connector P2000 pin 2 along
with A+ through P2000 pin 1. When AC_POWER_GOOD is at a logic High (AC voltage present), the
circuitry on this board will light the power-on LED green. When AC_POWER_GOOD is at a logic Low
(DC voltage present), the circuitry on the GCAI board will light the power-on LED amber. The second
routing location of AC_POWER_GOOD is OMAP input AC_PG_OMAP (U400 pin W10 through octal
buffer U1500). This lets the Consolette detect the presence of an AC voltage source. A+ is also
routed via the Mainboard to the front panel display board (PPLN7789A) through display connector
P110 pins 8 &10 and to the Consolette fan through fan connector P20 pin 1.
On the Mainboard itself, A+ feeds five devices, the main 5 volt, 3A switching regulator (U1300), a 3.3
volt, 50 mA unswitched linear regulator (U1305) used to power the on/off circuitry, an adjustable 50
mA unswitched linear regulator (U1319) used to provide the necessary wireline voltages (provides
9.6V which is divided down to also supply 4.8V and 2.2V), a MOSFET switch used to provide SWB+,
and a MOSFET switch used to provide ignition for the O5 control head and APX transceiver. The 5
volt regulator feeds the TI TPS65010 power management IC, which provides power to the rest of the
board; furthermore, the 5 volt regulator also feeds the regulators used to generate 2.85V and 1.5V.
SWB+ feeds regulators which supply the 4.8V biasing for the headset microphones and the 9.6V and
4.8V for the headset speakers' volume control. SWB+ is also made available on the rear panel 14-
pin Terminal Connector J103 pins 4, 6, and 8 for intended use with a relay coil. Each of these three
SWB+ paths have a maximum current rating of 150mA.
68009482001 September 9, 2011