Panasonic KX-TC2105RUB / KX-TC2105RUS / KX-TC2105RUT / KX-TC2105RUW Service Manual ▷ View online
14.6.3. RF signal operation/control and PLL operation (RF UNIT)
Base unit radio frequency signal received by antenna passes through duplexer (DPX401).
RF signal is amplified by RF AMP. RF signal received from RF IC is mixed with RX local frequency at Mixer to generate
10.7 MHz wide band IF. The reference frequency is generated by X801 10.240 MHz crystal.
The 10.7 MHz is mixed with reference and 450 KHz narrow band IF is generated.
RF IC is controlled by CPU (RF EN, RF DATA, RF CLOCK). The RX local frequency is generated by RX VCO.
37
KX-TC2105RUB / KX-TC2105R US / KX-TC2105R UT / KX-TC2105RUW
15 BLOCK DIAGRAM (HANDSET)
RF IC
IC801
IC801
DUPLEXER
DPX1
RF AMP
Q801,T801
RX VCO
T804,C831
1st IF
Filter
1st Mixer 2nd Mixer
2nd IF
Filter
IF
Filter
DET
PRE AMP
EXPANDER
SPEAKER AMP
DATA AMP
DATA Filter
Filter
1st Local
Crystal
PLL
Osc
TX PD
RX PD
MIC AMP
LIMITER
COMPRESSOR
POWER
DOWN
MODULATION
TX VCO
Q804,T803,
DV1
TX AMP
Q802,T802
RF DATA
RF CLOCK
RF EN
POWER DOWN
RX DATA
MCU
CPU
IC701
SPEAKER
MIC
TX DATA
Crystal
Battery
+
-
Q705
Charge Detection
Key Matrix
Reset
Q704
Q701,Q702
Buzzer
DC3.9V
KX-TC2105 BLOCK DIAGRAM (HANDSET)
KX
-T
C210
5RUB
/
K
X
-T
C
2105R
US
/
K
X
-T
C
2105R
UT
/
K
X
-T
C
210
5RUW
38
16 CIRCUIT OPERATION (HANDSET)
16.1. Outline
Handset consists of the following ICs as shown in BLOCK DIAGRAM (HANDSET) (P.38).
•
•
•
•
CPU: IC701
−
−
−
−
Forming/analyzing all data signals (ACK or CMD signal)
−
−
−
−
All interfaces (ex; LED, Key, Buzzer, Detector Circuit, Charge/Battery Low)
−
−
−
−
RAM for keeping the data (CH Number, ID Code, etc.)
•
•
•
•
RF IC: IC801
−
−
−
−
PLL Oscillator
−
−
−
−
Detection
−
−
−
−
Compress/Expander
−
−
−
−
1st/2nd mixer
−
−
−
−
Amplifier for transmission and reception
16.2. Reset Circuit
The power of handset is supplied by battery.
Whenever the battery is recharged or inserted, the impulse at CHG+ becomes Reset signal through Q704, and it is sent to CPU.
<Fig. 4>
<Fig. 5>
39
KX-TC2105RUB / KX-TC2105R US / KX-TC2105R UT / KX-TC2105RUW
16.3. Battery Low / Power Down Detector
Circuit Operation:
“Battery Low” and “Power Down” are detected by RF IC which check the voltage from battery. Shortly, every detected blocks
are inside of RF IC. The detected voltage is as follows;
are inside of RF IC. The detected voltage is as follows;
•
•
•
•
Battery Low
Battery voltage : V(Batt) < 3.457V
The CPU detects the level and “Recharge battery” LED starts flashing.
•
•
•
•
Power Down
Battery voltage : V(Batt) < 3.0V
The output of RF IC (Power Down) becomes low level, then CPU stops working to keep the data (CH number, ID Code, etc.)
<Fig. 6>
40
KX-TC2105RUB / KX-TC2105R US / KX-TC2105R UT / KX-TC2105RUW
Click on the first or last page to see other KX-TC2105RUB / KX-TC2105RUS / KX-TC2105RUT / KX-TC2105RUW service manuals if exist.