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Circuit Description
2-2. Baseband Circuit description of SGH-D820
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).
- Pulse-Width Modulator
The Backlight Brightness Modulator (BBM) contains a programmable Pulse-width modulator (PWM) to modulate the
intensity of a series of LED's or to control a DC/DC converter that drives LCD backlight.
This phone is using PWM control to modulate the LCD backlight brightness.
- 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
D820 has just one 2.12" TFT LCD. 16-bit data lines(LD(0)~LD(15)) transfers data and commands to LCD. There are
couple of control signals such as RS, LCD_MAIN_CS, L_WRB, etc. RS stands for "Register Select pin." When RS = 0,
data can be written to the index register or status can be read, and when RS = 1, an instruction can be issued or data
can be written to or read from RAM. Read or write operation is selected according to L_WRB signals. The data is
received when the R/W bit is 0, and is transmitted when the R/W bit is 1.
input, serial data transfer is initiated. On the other hand, at the rising edge of LCD_MAIN_CS input, the data
transfer is ceased.
2-2-3. Key
Key recognition part is consisted of 8 ports from PCF5213EL1. KEY_ROW(0:4) & KEY_COL(0:4)
These signals performs with the matrix. Any input from the matrix informs the key status to key interface in the
PCF5213EL1. Power on/off key is independent of the matrix. Therefore, 'power on/off' signal is directly connected with
PCF50603 to turn PCF50603 on.
Two 3.3V LDOs(U716, U823) enable Main and Sub Key LED on. Main and Sub Key LED are controlled by
KEYLED_ON and SLIDER_KEY_ON signal respectively.
SAMSUNG Proprietary-Contents may change without notice
This Document can not be used without Samsung's authorization
At the falling edge of LCD_MAIN_CS
2-2
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