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SG H- X100 Circuit Description
2. Baseband Circuit description of SGH-X100
1) PCF50601
1.1 Power Management
Ten low-dropout regulators designed specifically for GSM applications power the terminal and help ensure optimal system
performance and long battery life. A programmable boost converter provides support for 1.8V, 3.0V, and 5.0V SIMs, while
self-resetting, electronically fused switch supplies power to external accessories. Ancillary support functions, such as RTC
module and High Voltage Charge pump, Clock generator, aid in reducing both board area and system complexity.
I2C BUS serial interface provides access to control and configuration registers. This interface gives a microprocessor full
control of the PCF50601 and enables system designers to maximize both standby and talk times. Supervisory functions.
including a reset generator, an input voltage monitor, and a temperature sensor, support reliable system design. These
functions work together to ensure proper system behavior during start-up or in the event of a fault condition(low
microprocessor voltage, insufficient battery energy, or excessive die temperature).
1.2. Backlight Brightness Modulator
The Backlight Brightness Modulator (BBM) contains a programmable Pulse-width modulator (PWM) and FET to modulate
the intensity of a series of LED or to control a DC/DC converter that drives LCD backlight. This phone (SGH-X100) is
not use PWM, but use DC CONTROL (BACKLIGHT). So "BACKLIGHT" voltage is high value, backlight is bright.
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1.3. Clock Generato
The Clock Generator (CG) generates all clocks for internal and external usage. The 32768 Hz crystal oscillator provides an
accurate low clock frequency for the PCF50601 and other circuitry.
2) Connector
2-1. LCD Connector
LCD is consisted of main LCD(color 65K STN LCD). Chip select signals in the U304, LCD_CS can enable LCD.
LCD_CS signal is LCD select signal. This signal is from ENABLE part of OM6357.
"RESET_2V8" signal initiates the Reset process of the LCD.
16-bit data lines(HD(0)~HD(15)) transfers data and commands to LCD through by pass capacitor. Data and commands use
"RS" signal. If this signal is high, Inputs to LCD are commands. If it is low, Inputs to LCD are data. The signal which
informs the input or output state to LCD, is required. But this system is not necessary this signal. So "L_WR" signal is
used to write data or commands to LCD. Power signali for LCD is "VDD3".
2-2. Key
This is consisted of key interface pins among OM6357, KBIO(0:7). These signals compose the matrix. Result of matrix
informs the key status to key interface in the OM6357. Power on/off key is seperated from the matrix. So power on/off
signal is connected with PCF50601 to enable PCF50601. Ten key LEDs use the "VDD_KEY" supply voltage.
"VDD_KEY" signal enables LEDs with current control.
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