17
(Model KX-FP320E/KX-FM330E)
KX-FP320E/KX-FM330E
6.12. SPECIAL CIRCUIT ON THE ANALOG BOARD
6.12.1. CURRENT DETECTION CIRCUIT
1. Function
This circuit detects whether the circuit current is flowing or not. It is also used for CPC detection and Ext. Tel Hook
detection.
2. Circuit Operation
If a circuit current of 10 mA or more flows in the IC1 coil when the unit or Ext. Tel is OFF-hook, the IC1 internal sensor
detects this current. Then, depending on the direction of the current, the IC1-5 pin or 6 pin switches to a low level.
Then, Q1 or Q2 is turns off, Q18 turns on, and the Gate Array IC4-43 pin on the digital board switches to a low level. If
the line is cut off, the IC4-43 pin switches to a high level.
6.12.2. LOW PASS FILTER
1. Function
This circuit is only incorporated into the products designed for the German market. Products for other markets are
shorted by J33. This low pass filter attenuates the 16-kHz account signal from the commutator to eliminate influence on
the conversation and communications.
2. Circuit Operation
This low pass filter is an eighth-order active filter, and the cutoff frequency is approximately 4 kHz.
Circuit Diagram
RLY1
C3 R7
B
A
EXT.TEL
CN9(2)
(Digital)
IC4 43
Q2
Q1
Q18
R44
Line
A
B
IC1
1 2 5 6
R192
Circuit Diagram
Deletion
Level
frequency
IC11
IC11
IC12
IC12
C61
C63
C55
C62
C65
C66
C60
C58
R78
R86 R81
R77
R82
R88
R94
R91
J33
R79
C54
dB
0
-48dB/oct
4KHz
RX Signal
input
RX Signal
output
(Change from original page 176)
