2-8 Theory Of Operation: Major Assemblies
The output audio signal of Audio Processor IC is directed to volume control switch (SW/VOL1)
controlled by user and is finally amplified by U601BTL Audio Amplifier to a sufficient level to drive
either the external or internal speaker.
2.2.6 Microcontroller
The microprocessor or CPU includes Microprocessor (U101), EEPROM and support components.
Radio operation is controlled by software in internal Flash ROM memory.
Radio parameters and customer specific information is stored in External EEPROM (U104). Pins 35
& 36 controls the Sub-PCB mounted LED indicators. PTT button (PB501) is linked to CPU via pin 44.
Side programmable buttons 1 & 2 (PB502 & PB503) is linked via pin 21 & 32, respectively.
Customer Programming Software (CPS) connects to the radio via a USB Programming cable
(PMDN4077_R) through the microphone port (J601 pin 6) to pin 34 & 33 (PRG/CLONE_RX & PRG/
CLONE_TX port). A 7.3728 MHz clock signal (X-in) is provided by FL101 to CPU. A voltage divider
system (R153 & R154) is used by CPU to sense battery level.
2.2.7 Power Supply
There are 4 voltage supplies in this radio: SWB+, 3.3 V, 5 V & 10 V.
SWB+ voltage is distributed to SW/Vol 1, Final PA (Q403 via R417) & APC circuit (U401).
The 3.3 V regulated supply (U506) is applied to CPU (U101), EEPROM (U104), DTMF IC (U103),
Audio processor IC (U102), microphone biasing circuit and LCD/keypad driver.
The 5.0 V regulated source (U505) is distributed to RX back end circuit, RX/TX audio filters,
1/2 VCC generator, VCO (Q705, Q706), RX B+ (Q304), TXvB (Q407) & VCTCXO.
The 10.0 V regulated source (U507) is solely applied for Charge pump use.
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