Samsung SGH-D600 Service Manual page 6

Circuit Description
2-2. Baseband Circuit description of SGH-D600
2-2-1. PCF50603 (U400)
- Power Management
Eight 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 SIMs,
while a 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 PCF50603 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).
- Clock Generator
The Clock Generator (CG) generates all clocks for internal and external usage. The 32.768 kHz crystal oscillator
provides an accurate low clock frequency for the PCF50603 and other circuitry.
2-2-2. LCD
LCD is consisted of main LCD(color 262K TFT LCD).
Chip select signals in the U301, LCD_MAIN_CS, can enable LCD. BACKLIGHT signal enables white LED of main LCD.
16-bit data lines(LD(0)~LD(15)) transfers data and commands to LCD. 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_WRB" signal is used to write data or
commands to LCD. Power signals for LCD are "VDD_IO_HIGH".
2-2-3. Key
This is consisted of key interface pins KEY_ROW(0:4) and KEY_COL(0:4) in PCF5212EL1. These signals compose the
matrix. Result of matrix informs the key status to key interface in the PCF5212EL1. Power on/off key is seperated from
the matrix. So power on/off signal is connected with PCF50603 to enable PCF50603. Key LED is consisted of six white
LEDs for sub key and twelve white LEDs for main key. White LED for sub key use the VBAT voltage.
"SLIDER_KEY_ON" signal enables Transistor for sub key backlight.
Main key LED use the 3.3V LDO for a supply voltage. KEY_LED_ON signal enables eight white LED.
"FLIP" informs the status of slide (open or closed) to the PCF5213EL1. This uses the hall effect IC, EM-1681
A magnet under LCD enables EM-1681.
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