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KX-TCA275CE
4.2.
Circuit Operation (Handset)
4.2.1.
Outline
Handset consists of the following ICs as shown in Block Diagram (Handset) (P.7).
• BBIC (Base Band IC): IC3
- All data signals (forming/analyzing ACK or CMD signal)
- All interfaces (ex: Key, Detector Circuit, Charge, LCD, LED, SRAM, Flash ROM)
• SRAM: IC1
- Application data and code are temporarily stored.
• Flash ROM (substitute EEPROM): IC2
- Source program data and temporary user data are stored.
• AMPLIFIER IC: IC5
- Single OP_AMP for SPEAKER
• RF Module:
- PLL Oscillator
- Detector
- Compress/Expander
- Amplifier for reception
- Amplifier for transmission
4.2.2.
Power Supply Circuit/Reset Circuit
When power on the Handset, the voltage is as follows;
BATTERY(3.5 V to 4.2V: Battery+) → Q8 (1.8V) → Q10 (3.0V)
The reset signal is generated with IC3 and Q17.
Power for RF IC (IC601) is generated with IC603.
5.0V for LCD back-light is generated with IC4.
Battery (3.5V to 4.2V) is used for RF Module, Amplifier IC (IC5), Vibrator, DC/DC Converter (IC4).
1.8V is used only for BBIC (IC3).
3.0V is used for BBIC (IC3), LCD, SRAM (IC1), Flash ROM (IC2), Red LED, Green LED, Key back-light.
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