Advertisement
Function
ISDN Block
ISDN circuit interface
Expansion
Current Supply
Block
Hook Detection
Ring Trip Detection
2W-4W Lines Conversion
A/D and D/A conversion
Door-phone Door-phone Calling
detection
Door Opener Controller
Function
Current supply
Detect connection of Door-
phone
Internal Music on Hold
Voltage Watching Function
Back-up Function
Bell Signal Generator Function
2.2. KX-TD612 Block Diagram
2.3. EXPLANATION OF CIRCUIT OPERATION
2.3.1. POWER SUPPLY UNIT
1. DC voltage generation circuit:
A. Switching section
The switching frequency is 80kHz. Q1 is PWM-controlled by IC1
in order to regulate the output voltage. Secondary voltage
detection is performed by R113, R114 and VR101, and changes
in the secondary voltage with respect to the base voltage of
Q101 are isolated by photo coupler PC1 and sent to IC1.
B. Secondary circuit
At first, it produces +26V DC voltage. And it produces +5V DC
voltage from voltage drop chopper circuit.
2. Ringing signal output function:
Ringing signal (25Hz, 8Vac from main board) is amplified in power
by power amplifier circuits (including of IC301, IC304, R301-307,
C301-303 and D301). Ringing signal amplified in power is
This is an interface circuit to connect ISDN lines and the
Supplies the communicative current to SLT.
Detects On-Hook and Off-Hook when a bell signal is not
Detects Off-hook when a bell signal is presented.
Converts 2W signals from SLT to 4W signals.
Conducts a conversion between 4W analog signals and
digital signals by CODEC.
Detects a calling sign from a door-phone side.
Has one channel of relay contact output for a door opener
controller.
Supplying the current to the Door-phone.
Detect if the Door-phone is connected.
Possible by Music on Hold IC.
Observes +5V and +15V voltages. It conducts the system
when +5V voltage is derated.
-
Back up the around CPU (+5V) when AC power momentarily fails.
-
Back up the system data of RAM by lithium battery.
Generates 25 Hz signal from I/O port of G/A, Amplifies and
voltage by power amplifier and transformer, and supplies
extensions.
12
Content
Advertisement
