Motorola ASTRO MT 1500, Service Manual

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6816985H01-B August 16, 2007
UHF2 Radio Power: B+ and +5V Routing for VOCON 3.3-3
3.3.5 B+ and +5V Routing for VOCON
Refer to Figure 3.3-2 and the appropriate schematic diagrams in the back of this manual.
Figure 3.3-2. XTS 2500/XTS 2500
I
DC Distribution (for all other kits)
Power for the radio is derived from a 7.5 volt battery (), which is applied to the power
mosfet (Q703 and Q700) in the RF and VOCON sections respectively.
Q700 is a power mosfet switch that provides SW_B+ to the MAKO IC to U500 (the 5V regulator) in
the RF section.
The digital circuits in the VOCON section are powered from regulators located in the MAKO IC. The
MAKO IC provides five software-programmable supplies (VSW1, V1.55, V1.875, V2.9 and VCC5).
VSW1 provides voltage to U502 that regulates 3 Volts to digital circuits, while U500 supplies to U501
that power analog circuits with 3 Volts in the RF section. The initial and programmed output of VSW2
(C715) is 2.3V. The VSW2 is used internal to the MAKO IC to supply the 1.875V (V1.875) and 1.55V
(V1.55) linear voltage regulators.
Battery
7.5 Volts
(Nominal)
RF Section
Fuse
U500
5 Volts
U501 U502
3 Volts
Analog Circuits
3 Volts
Digital Circuits
Q700 Q703
U701
SW_B+
3.6 V (VSW1)
1.875 Volts
(V1.875)
5 Volts
(VCC5)
1.55 Volts
(V1.55)
2.9 Volts
(V2.9)
VOCON Section