LG MX8550, Service Manual

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- 35/148 - LG Electronics Inc.
M X8550
2.3.4 Memory Part
MCP contents 1Gbits NAND FLASH memory and 512Mbits SDRAM. In the NAND Flash Memory part of MCP
are programs used for terminal operation. The programs can be changed through downloading after the assembling of
terminals. On the SDRAM data generated during the terminal operation are stored temporarily.
2.3.5 Power Supply Part
When the battery voltage (+4.0V) is fed and the PWR key of keypad is pressed, U303(PMIC) is activated by the
PWR_ON_SW signal, and The PWRON signal is held high, Buck and LDO1,2,3 are turned on; when LDO1 reaches
87% of its final value a 60ms reset timer is started at after which RESET\ is asserted high. Now the BB Processor is
initialized and will assert PWRHOLD high. PWRHOLD maintains the power on.
The Buck/LDO1,2,3 are generating the +1.4V_MSMC, +2.6V_MSMA, +1.8V_MSMP1 and +2.8V_LCD
respectively.
The Rx part LDO(Out5) is operated by the control signal SLEEP/ from MSM6500
The Tx part LDO(Out4) is operated by the control signal IDLE/ from MSM6500.
The TCXO part LDO(Out7) is operated by the control signal TCXO_EN/ from MSM6500.
2.3.6 Logic Part
The logic part consists of internal CPU of MSM, RAM, MCP. The MSM6500 receives TCXO (=19.2MHz) from
the X100 and controls the phone in CDMA modes. The major components are as follows:
CPU
The ARM926J-S microprocessor includes a 3 stage pipelined RISC architecture, both 32-bit ARM and 16-bit
THUMB instruction sets, a 32-bit address bus, and a 32-bit internal data bus. It has a high performance and low
power consumption.
MCP
NAND Flash is used to store the terminal’s program. Using the down-loading program, the program can be
changed even after the terminal is fully assembled.
SDRAM is used to store the internal flag information, call processing data, and timer data.
KEYPAD
For key recognition, key matrix is setup using KYPD[1][3][5][7][9][11][13][15][17]signal from MSM6500. 2
LEDs and backlight circuitry are included in the keypad for easy operation in the dark.
TOUCH KEYPAD
For key recognition, U106 communicates with MSM6500 by using TOUCH_DATA, TOUCH_CLK,
TOUCH_ACK. 4 LEDs and backlight circuitry are included in the keypad for easy operation in the dark. Touch
keypad also supports vibe-touch function when pressing is recognized.
LCD MODULE
LCD module contains a controller which will display the information onto the LCD by 16-bit data from the
MSM6500. It is also supplied 2.8V_LCD by Out3 in U303 for fine view angle and LCD reflects to
improve the display efficiency. 3 LEDs is used to display LCD backlight.
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