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KX-F910BX
13-7. CIRCUIT OPERATION OF PORTABLE HANDSET
(1) RF Transmission/Reception Power Supply Circuit
The power source for transmission is switched on and off by the CPU that controls Q14, Q16 and Q17 for
battery current. It is stabilized the constant voltage by the 3 V regulator and supplied to the RF unit and IF
IC. In the standby mode, Q16 is switched ON and 3 V is supplied to the RXB via IC3 only when pin
becomes Low. In the TALK mode, when pins and are set to Low and Q16 and Q17 is switched ON,
approx. 3 V is supplied to the RXB via IC3 and TXB via IC8. And then, pin is set to Low, Q14 is ON and
approx. 3 V is supplied to the TXPB .
22
23
31
23
Q16
IC3
Reg.
3.0V
IC8
Q14
Q17
22
23
31
RXB
TXPB
TXB
CPU
TX PLL
CPU
RX POWER
CPU
TX POWER
+
–
Reg.
3.0V
(2) Electric Field Detection Circuit
The electric field detection circuit that consists of the DET Amp., IC1's noise filter, integration circuit and
comparator detects the electric filed by checking noise.
The audio signal output from pin of CN1 extracts noise of approx. 18 kHz by the noise filter of IC1 after it is
amplified by the DET amplifier. After the noise is converted to the De voltage in the integration circuit, it is input to
the comparator to gain High and Low outputs.
Pin decides the sensitivity of the integration circuit and pin decieds the time constant.
In the strong electric field, the De voltage of pin is 0.5 V or less, pin outputs Low.
In the weak electric field, the De voltage of pin is approx. 1 V, pin outputs HIGH.
Integration circuit
1
49
52
52
52
48
48
Circuit Diagram
CN1
Audio
C20
VR1
R116
C74
C64
R117
R118
DET Amp.
C63
R13
Q15
C19
C18
R1
(IC1)
Noise
Filter
1.9V
–
Integration Circuit
Comparator
R9
R11
C16
1
54
55
49
52
R8
48
CPU
19 pin
+
C202
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