Motorola APX 7500, Подробное руководство по обслуживанию

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September 9, 2011 68009482001
2-2 Theory of Operation: Power Distribution
2.2.1 5 Volt Regulator
U1300 is a 5 volt (VCC_5V) switching regulator with a 3A maximum output current. It supplies all the
power for the Mainboard with the exception of the ON/OFF circuits. In addition to being the voltage
source for many of the Mainboard’s pull-up resistors, VCC_5V also supplies power to the RS232
transceiver U1704 and is the USB Host interface’s VBUS source. VCC_5V is also the voltage source
for the backlight LEDs on the keypad board and display board. VCC_5V is made available on the
rear panel DB25 Accessories Connector J104 pin 18 for intended use with a relay coil. This VCC_5V
path has a maximum current rating of 150mA. The regulator output is controlled by the ATMEL AVR,
U1311, using enable pin 7 on the regulator. When the enable pin is driven low, the regulator enters
standby mode with a quiescent current of 50 A.
2.2.2 3.3 Volt Unswitched Regulator
U1305 is a Texas Instruments TPS71533 low drop-out 3.3 volt (UNSW_3.3V) regulator with a 50mA
maximum output current. This regulator draws a quiescent current of 3.2 A and is used to power the
ON/OFF circuitry, real time clock, OMAP McBSP2 muxes, and CAN termination circuitry. This
regulator is active whenever A+ is applied to the Consolette.
2.2.3 Wireline Voltage Regulator
U1319 is a Texas Instruments TPS71501 low drop-out adjustable regulator with an output current of
50mA. The voltage is set to within 5% of 9.6V (9.6V_WL); furthermore, using a voltage divider circuit,
the 9.6V is divided down to 4.8V (4.8V_WL) and 2.2V (2.2V_WL). These are the voltages used for
the various op amp, comparator, and switches on the wireline. This regulator is self enabled with A+
as the input voltage.
2.2.4 TPS65010 Power Management IC
The Texas Instruments TPS65010 power management IC, U1301, provides several voltages used
by the OMAP microcontroller and peripheral devices. It also provides the proper power-on sequence
of these voltages. The TPS65010 is supplied by the 5 volt switching regulator. It contains two
stepdown converters and two low drop-out regulators. VMAIN is a step-down converter with a 1A
maximum output current. In addition to supplying 3.3 volts (VCC_3.3V) to some of the Mainboard
peripherals (and the divided down 1.35 volts, labeled VCC_1.35V, used for audio biasing), VMAIN
also supplies the internal VLDO1 and VLDO2 regulators. VCORE is a step-down converter with a
400mA maximum output current. VCORE is used to provide the 1.6 volt (VCC_1.6V) OMAP core
voltage. Both VLDO1 and VLDO2 are low-dropout regulators with 200mA maximum output current.
VLDO1 provides 2.8 volts (VCC_2.8V) to most of the OMAP I/O pins and external peripherals on the
Mainboard, along with supplying 2.8 volts to the keypad board (PPLN7788A) and display board
(PPLN7789A) for both boards’ keypad matrix pull-up resistors. VLDO2 provides 1.8 volts
(VCC_1.8V) that is used mainly by the Codec digital section, FLASH memory, and SDRAM memory.
2.2.5 2.85 Volt Regulator
U1304 is a Texas Instruments TPS73201 low drop-out adjustable regulator with an output current of
250mA. The voltage is set to within 2% of 2.85V. This voltage is used for the Codec analog and I/O
section, Nautilus FPGA circuitry, and USB transceivers’ circuitry. VCC_5V is the input voltage to
U1304, as well as its enable input pin 5; therefore, the 2.85 volt regulator is on whenever VCC_5V is
present.
2.2.6 1.5 Volt Regulator
U1307 is a National Semiconductor LM317A adjustable regulator with an output current of 1A. The
voltage is set to within 2% of 1.5 volts (VCC_NAUT_1.5V). This regulator provides the core voltage
to the Nautilus FPGA and is self enabled with VCC_5V as the input voltage.