Samsung SGH-X640 Service Manual page 7

16-bit data lines(LD(0)~LD(15)) transfers data and commands to LCD through bypass 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 state of LCD is whether input or output, is required. But in this system, there is no input
state from LCD. So only "L_WR" signal is used to indicate write data or command to LCD. Power signals for LCD are
"VBAT and "VDD2".
"M_SCL", "M_SCA", "PCLK", "FVALID", "LVALID" and "STANDBY" signals are all related to camera working.
"SVC_LED" is signal for service led when the signal is low led is on and vice versa. "SPK_P" and "SPK_N" are used
for audio speaker containing voice or melody. And "VDD_VIB" from PCF50601 enables the motor.
3. Key
This is consisted of key interface pins among OM6359, KBIO(0:7). These signals compose the matrix. Result of matrix
informs the key status to key interface in the OM6359. Power on/off key is separated from the matrix. So power on/off
signal is connected with PCF50601 to enable PCF50601. Fifteen key LEDs are use the "VBAT" as supply voltage.
"VDD_KEY" signal enables LEDs. "FLIP" informs the status of folder (open or closed) to the OM6359. This uses the
hall effect IC, SH248CSP. A magnet under main LCD enables SH248CSP.
4. EMI ESD Filter
This system uses the EMI ESD filter, EMIF09 to protect noise from IF CONNECTOR part.
5. IF connetor
It is 18-pin connector. They are designed to use VBAT, V_EXT_CHARGE, TXD0, RXD0, RTS0, CTS0, JIG_REC,
CHARGER_OK, RXD1, TXD1, AUX_MIC, AUX_SPK and GND. They connected to power supply IC, microprocessor
and signal processor IC.
6. Battery Charge Management
A complete constant-current/constant-voltage linear charger is used for single cell lithium-ion batteries.
If TA connected to phone, "V_EXT_CHARGE" enable charger IC and supply current to battery.
When fault condition caused, "CHG_ON" signal level change low to high and charger IC stop charging
process.
7. Audio
EARP_P and EARP_N from OM6359 are connected to the main speaker. AUXSP is connected to the Hands free kit.
MIC_P and MIC_N are connected to the main MIC. And AUX_MIC_P and AUX_MIC_N are connected to the Hands
free kit.
YMU762C is a LSI for portable telephone that is capable of playing high quality music by utilizing FM synthesizer and
ADPCM decoder that are included in this device.
As a synthesis, YMU762C is equipped 32 voices with different tones. Since the device is capable of simultaneously
generating up to synchronous with the play of the FM synthesizer, various sampled voices can be used as sound effects.
Since the play data of YMU762C are interpreted at anytime through FIFO, the length of the data(playing period) is not
limited, so the device can flexibly support application such as incoming call melody music distribution service. The
hardware sequencer built in this device allows playing of the complex music without giving excessive load to the CPU of
the portable telephones.
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Circuit Description