Samsung SCH-470 Service Manual

Also see for SCH-470: Owner's manual

Contents

Samsung SCH-470 Service Manual Manual pdf 15 page image

Samsung Electronics 5-15 . Circuit Descript ion5-1 Logic Section5-1-1 Power SupplyWith the battery installed on the phone and bypressing the END/ key, the VBATT andON_SW signals will be connected. This will turnon U123 DC_DC convertor.This in turn will be supplied to PIN3, PIN4 ofregulators U124, PIN6 of regulators U122, thusreleasing them from the shut-down state to outputregulated 3.3V. ( The VBATT applied to ON-SWwill turn on Q103(DTC144EE) resalting in thesignal ON-SW-SENSE to change start the fromHigh to Low.)The MSM recognizes this signal and sends outPS_HOLD (logical HIGH) to turn on Q102 evenafter the PWR key is released.The power from U124 is used in the digital part ofMSM and BBA. The power from U122 is used inanalog part of BBA.5-1-2 Logic PartThe logic part consists of internal CPU of MSM,RAM, ROM and EEPROM. The MSM receivesTCXO and CHIPX8 clock signals from the BBAand controls the phone during the operation. Themajor components are as follows:¶UCPU : INTEL 80186 core (inside the MSM)¶UFLASH ROM : U129 - 8 Mbit FLASH MEMORY¶USRAM : U127 - 2 Mbit STATIC RAM¶UFLASH ROM : U130 - 1 Mbit FLASH MEMORY¶UEEPROM : U102 - 128 Kbit SERIAL EEPROMCPUINTEL 80186 CMOS type 16-bit microprocessor isused for the main processing. The CPU controls allthe circuitry. For the CPU clock, 27MHz resonatoris used.FLASH ROMOne 8 MBIT FROM is used to store the terminal'sprogram. Using the down-loading program, theprogram can be changed even after the terminal isfully assembled.SRAMOne 2 MBIT SRAMs is used to store the internalflag information, call processing data, and timerdata.EEPROMOne 128 KBIT EEPROM is used to store ESN,NAM, power level, volume level, and telephonenumber.KEYPADFor key recognition, key matrix is setup usingSCAN0-6 of STORE signals and KEY0-3 of inputports of MSM. Ten LEDs and backlight circuitryare included in the keypad for easy operation inthe dark.LCD MODULELCD module contains a controller which willdisplay the information onto the LCD by 8-bit datafrom the MSM. It also consists a DC-DC converterto supply -3.5V for fine view angle and LCDreflector to improve the display efficiency.