Panasonic KX-DT333UA Service Manual ▷ View online
9
KX-DT333UA/KX-DT333UA-B
4.2.4.
Reset Circuit
Reset Signal is outputted from IC3 and inputted into IC1 and IC2 at the connection of TEL cord.
4.2.5.
Power Supply Circuit
This circuit converts the voltage supplied from PBX into the power supply voltage of +3.3V by IC5 (Switching Regulator IC).
IC10 controls the power supply circuit as below to turn IC5 on in low consumption current at starting up.
IC10 controls the power supply circuit as below to turn IC5 on in low consumption current at starting up.
• Input Voltage approx. 20V or less
→ L →IC5 ON
• Input Voltage approx. 20V or more
→ Q5 C (Collector) HiZ→IC6 OFF
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KX-DT333UA/KX-DT333UA-B
4.2.6.
Data Communication
Function
The data communication circuit serves the following functions:
Information exchanger between PBX and proprietary telephone, key input information as well as data for the LED control, LCD
control, voice data, etc. This information is continuously exchanged at all times.
Information exchanger between PBX and proprietary telephone, key input information as well as data for the LED control, LCD
control, voice data, etc. This information is continuously exchanged at all times.
Circuit Operation
The data received from PBX is inputted to the comparator (pin 68) built in IC2 through Pulse Trans T1. The threshold voltage of
the comparator is determined by R19 to 21 and inputted to pin 67 and 69.
The data to PBX is outputted from pin 70 and 71 of IC2, drives T1 by Transistor Q1 and transmitted.
the comparator is determined by R19 to 21 and inputted to pin 67 and 69.
The data to PBX is outputted from pin 70 and 71 of IC2, drives T1 by Transistor Q1 and transmitted.
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KX-DT333UA/KX-DT333UA-B
4.2.7.
DXDP Communication
Function:
This circuit performs the same type of communication as between the DPT and PBX, but for a DXDP-compatible DPT con-
nected to the DXDP port.
In addition, power feed is also controlled.
nected to the DXDP port.
In addition, power feed is also controlled.
Circuit Operation:
The data to the slave DPT is output from pins 63 and 64 of IC2 and sent via the pulse transformer T2 to JK2.
The data from the slave DPT is sent through the pulse transformer and is input to the comparitor (pin 61) built into IC2.
The threshold of the comparitor is determined by R19 to R21, which is input into to pins 60 and 62 of IC2.
The data from the slave DPT is sent through the pulse transformer and is input to the comparitor (pin 61) built into IC2.
The threshold of the comparitor is determined by R19 to R21, which is input into to pins 60 and 62 of IC2.
Power is supplied to the Slave DPT by means of a constant current circuit Q3 and Q4 as below:
• IC2 pin 58 H: Constant current circuit ON.
• IC2 pin 58 L: Constant current circuit OFF.
• IC2 pin 57 H: 40mA feed (normal supply to attached Slave DPT).
• IC2 pin 57 L: 20mA feed (initial supply to Slave DPT).
• IC2 pin 58 L: Constant current circuit OFF.
• IC2 pin 57 H: 40mA feed (normal supply to attached Slave DPT).
• IC2 pin 57 L: 20mA feed (initial supply to Slave DPT).
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KX-DT333UA/KX-DT333UA-B
4.2.8.
Analog Circuit
This circuit performs the setting of the call path/vol. adjustment in each call mode by DSP built in IC2.
The audio gain of each call is determined by download data from PBX.
The audio gain of each call is determined by download data from PBX.
• IC2 sends each audio data to IC6 by PCM interface.
• IC2 receives each audio data from IC6 by PCM interface.
• IC2 receives each audio data from IC6 by PCM interface.
1. Handset Call
Transmitting signal is inputted from handset microphone and amplified by IC6 built-in Amp
→ A/D conversion→inputted to IC2
in PCM data
→Gain adjustment by DSP of IC2→then sent to PBX.
Transmitting signal inputted from handset microphone is controlled by transmission switching SW IC8 as below.
IC1-pin 52 L : Handset Call
(IC1-pin 52 H : Headset Call)
Receiving signal inputted from PBX is
IC1-pin 52 L : Handset Call
(IC1-pin 52 H : Headset Call)
Receiving signal inputted from PBX is
→Gain adjustment by DSP of IC2→D/A conversion after the input to IC6 in PCM
data
→IC6 built-in Amp output→outputted from IC2 built-in Amp to handset.
2. Headset Call
Transmitting signal is inputted from headset microphone and amplified by IC6 built-in Amp
→ A/D conversion→inputted to IC2
in PCM data
→Gain adjustment by DSP of IC2→then sent to PBX.
Transmitting signal inputted from headset microphone is controlled by transmission switching SW IC8 as below.
IC1-pin 12 H : Headset Call
(IC1-pin 12 L : Handset Call)
Receiving signal inputted from PBX is
IC1-pin 12 H : Headset Call
(IC1-pin 12 L : Handset Call)
Receiving signal inputted from PBX is
→Gain adjustment by DSP of IC2→D/A conversion after the input to IC6 in PCM
data
→IC6 built-in Amp output→outputted from Q6 (transistor for buffer) to headset.
3. Speakerphone Call
Speakerphone call realizes all double-call by DSP(echo canceller) built in IC2. For a call in the most appropriate condition,
DSP checks voice level of the calling party, acousticity in a room, voice level of the other party and state of the line of contact,
and cancels echo in transmitting and receiving at the start of calling. It operates in a half double-call state in a few seconds for
the check.
DSP checks voice level of the calling party, acousticity in a room, voice level of the other party and state of the line of contact,
and cancels echo in transmitting and receiving at the start of calling. It operates in a half double-call state in a few seconds for
the check.
Transmitting signal is inputted from SP phone mic. and amplified by IC6 built-in Amp
→ A/D conversion→inputted to IC2 in
PCM data
→Gain adjustment by DSP of IC2, then sent to PBX through echo canceller.
Receiving signal inputted from PBX is
→Gain adjustment by DSP through echo canceller of IC2 →inputted to IC6 in PCM
data
→D/A conversion→IC6 built-in Amp output→outputted from IC7(Amp) to speaker.
Power Amp IC7 is controlled as follows;
IC1-pin 13 L
IC1-pin 13 L
→IC7-ON
IC1-pin 13 H
→IC7-OFF
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