Samsung SF11OT Servise Manual

Circuit Description5-4-I Transmit Circuit 5-4-2 Receive Circuitf- F This circuitry controls transmission of analog In receive mode, analog signals from the LIUsignals from the MODEM. Output voltage from board are transferred to RX IN through the BPFthe MODEM is buffered through the LIU board and smoothing filter.and OP amp after signal smoothing and filtering,and finally output to the line.5-5 TADTAD circuit consists of a voice coprocessor to record and play voice messages in voice memory.5-5-l Recording Path 5-5-3 Line Input and Play PathR55 provides power to the condenser microphone.Voice signal from the microphone is passedthrough active filter U15, R117 and C96, R82, C58to clear aliasing noise occuring while samplingand amplifying the signal. Q5 and Q2 composeALC (Automatic Level Control) circuit. CODEC(U22) converts the voice signal to digital andconverts the digital signal from voice coprocessorinto analog for line output.Incoming signals from line are stored in the voicememory (4 M DRAM) through CODEC and DSPGDRAM controller. When played, DSPG processesthe data stored in voice memory and sends it outto LIU through CODEC and R108. To playbackthrough the speaker, DSPG sends the signal tospeaker through R108, MUX (U12, U14), and opamp.5-5-2 Mic Input PathTransmit path functions as MIC input path.Outgoing messages and memo messages fromCODEC are stored in the voice memory (4 MDRAM) through the DSPG DRAM controller.5-5-4 DSPGThis circuit consists of Host Interface, MemoryInterface, CODEC Interface, and DSP core. HostInterface sends and receives data to and from IFC.Memory Interface sends and receives thecompressed voice data to and from DRAM to playback and record voice data. DSP corecommunicates with host IFC through HostInterface.5-5-5 Voice Backup+5V is supplied for voice memory through VBTwhen power is on. When power is off, +5V issupplied from the 9V backup battery.Samsung Electronics 5-11