Motorola ASTRO XTS 5000 Detailed Service Manual page 66

Theory of Operation
: VOCON Board
3.2.3.6 EEPOT U509
The EEPOT is a digitally programmable potentiometer with 256 taps and a total resistance of
50 kohms. This 10-pin package contains two independent potentiometers, one for each microphone
line. The EEPOT resistance values are programmed by the Patriot IC GPIOs EEPOT_INC* (U509
pin 9) and EEPOT_U_D* (U509 pin 2). The EEPOT_INC* signal increments the resistance value up
or down, which depends on the EEPOT_U_D* signal. The EEPOT_CS* line (U509 pin 10) is
asserted when the internal microphone gain is being changed. Similarly, the EEPOT_CS_XST*
(U509 pin 1) is asserted for external microphone gain changes. The EEPOT is supplied with voltage
from the GCAP II V2 regulator.
3.2.3.7 MAKO IC U501 (for NNTN5567)
The MAKO IC is a mixed-signal IC that provides control, clock generation, digital support, audio, and
voltage regulation functionality. It comes in a 176-pin, ball-grid array (BGA) package with 0.8mm
pitch solder balls. The MAKO IC is supplied with switched battery voltage SW_B+.
3.2.3.7.1 Voltage Regulation
The MAKO IC contains all of the regulators that are used in the design of the VOCON board: VSW1,
VSW2, V_2.9, V1.55, V1.875, and VCC5. VSW1 is a programmable switching regulator controlled
by the MAKO IC on pin SW1_SUMCOMP_DL, while the current is sourced by a driver Q501 using
the switched battery voltage (SW_B+). The switching frequency of VSW1 (R511) is programmable
by the dual-core processor through the SPI bus. The VSW1 voltage is supplied to the to the input pin
of MAKO's VSW2 regulator (pin SW2_VCCS).
The VSW2 regulator is a SPI programmable switching regulator. The initial and programmed output
of VSW2 (C515) is 2.3 volts. The VSW2 voltage is used internal to the MAKO IC to supply the 1.875
volt (V1.875) and 1.55 volt (V1.55) linear voltage regulators. The V1.875 voltage is supplied to the
dual-core processor U401 (EIM voltage), SRAM U403, and Flash memory U402. The V1.55 voltage
(R518) is supplied to the dual-core processor U401 (core voltage).
The V_2.9 volt regulator is a linear regulator within the MAKO IC that used VSW1 as its input. The
initial output of V_2.9 is 2.775 volts, which is then programmed to 2.9 volts by the dual-core
processor via the SPI bus. The V_2.9 voltage is supplied to the dual-core processor (I/O ring - SPI,
BBP, SAP, UART, GPIO, etc.), the display module connector P301, and the many discrete
components that interface with the dual-core processor and the MAKO IC.
3.2.3.7.2 MCU Interface
The MAKO IC has a four-wire, SPI connection to the dual-core processor (SPI B). The SPI B clock is
connected to the SPI_CLK pin (TP_SCKB). The SPI B MOSI line is connected to the SPI_DI pin
(TP_MOSIB). The SPI B MISO line is connected to the SPI_DO pin (TP_MISOB). The MAKO SPI B
chip-select signal is connected to the SPI_CS pin (TP_MAKO_CE). Through this interface, the dual-
core processor can program the voltage regulators, the CODEC, the transmit and receive audio
filters and amplifiers, digital support multiplexing, and read information from the ADC.
The MAKO IC has a 10-bit ADC with eight general-purpose channels and two voltage-monitoring
channels. Five out of the eight general-purpose channels are assigned to the display backlight
button on the control head (ATOD_2), the monitor volume (ATOD_1), the two-position toggle switch
(ATOD_3), the OPT_SEL_IN (ATOD_8), and board type ID (ATOD_5). The other three general
purpose channels are unused. Battery voltage is also monitored by the ADC. The dual-core
processor reads the ADC values through the SPI bus.
6881094C31-E
3-27
November 16, 2006