Circuit Operation (Base Unit) - Panasonic KX-TS620BXB Service Manual

KX-TS620BXB/KX-TS620BXW
4.2.

Circuit Operation (Base Unit)

4.2.1. Outline
The unit consists of the following ICs as shown in the Block Diagram (Base Unit) (P.7).
• BBIC (Base Band IC): IC901
- Handling all the audio, signal and data processing needed
- ADPCM codec filter for speech encoding and speech decoding (DSP section)
- Echo-cancellation and Echo-suppression (DSP section)
- Any tones (tone, sidetone, ringing tone, etc.) generation (DSP section)
- DTMF receiver (DSP section)
- ADC, DAC, timer and power control circuitry
- All interfaces (eg: LCD, LED, Analog Front End, etc.)
• FLASH MEMORY: IC902
- Voice Prompt (TAM) Download Area
- Program D/L Area
• RINGER IC: IC1
- Bell signal generator (for bell detection purpose)
- Refer to Ringer IC (P.10)
• SP AMP: IC904
- Low voltage audio power amplifier
• Additionally,
- Power Supply Circuit (+4.0V, +4.0V, +3.2V, +1.8V output)
- Telephone Line Interface Circuit
- Bell Detection Circuit
- SP-Phone Circuit
- Handset Circuit
- TAM Circuit
4.2.2. Power Supply Circuit
The power is supplied to the BBIC, Flash ROM, SP AMP, Logic IC, LCD, LED from AC adaptor (6.5V) as below:
• BBIC (IC901): CN301 -> D304 -> IC304 -> Q702 -> IC901
• Flash Memory (IC902): CN301 -> D304 -> IC304 -> Q702 -> IC902
• Logic IC (IC905): CN301 -> D304 -> IC304 -> Q702 -> IC905
• SP AMP (IC904): CN301 -> IC305 -> IC904
• LCD (LCD): CN301 -> D304 -> IC304 -> Q702 -> L302 -> LCD
• LED (LED801, LED802): CN301 -> IC305 -> L301 -> CN403 -> CN801 -> LED
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