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KX-MB2000RUB/KX-MB2000RUW/KX-MB2020RUB/KX-MB2020RUW/KX-MB2030RUB/KX-MB2030RUW

1. Function

This unit has a lithium battery (BAT300) which works for the Real Time Clock IC (RTC: inside IC300).
The RTC continues to work, backed up by a lithium battery even when the power switch is OFF.

2. RTC Inside (IC300) Backup Circuit Operation

When the power switch is turned ON, power is supplied to the RTC (inside IC300). At this time, the voltage at pin AF3 of the
IC300 is +3.3V. When the power switch is turned OFF, the BAT300 supplies power to RTC through DA300. 
When the power switch is OFF and the voltage of +3.3V decreases, pin AF3 of RTC (IC300) becomes roughly the same volt-
age as the battery voltage. RTC goes into the backup mode, in which the power consumption is lower.

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KX-MB2000RUB/KX-MB2000RUW/KX-MB2020RUB/KX-MB2020RUW/KX-MB2030RUB/KX-MB2030RUW

The modem (Included IC300) has all the hardware satisfying the CCITT standards mentioned previously.
ALL processing is controlled by the SOC (IC300) according to CCITT procedures.
This modem (Included IC300) has an automatic application equalizer. With training signal 1 or 2 at the time of G3 reception, it can
automatically establish the optimum equalizer.  

The digital image data sent on ATXD line from modem (Included IC300) .
DAA IC100(6

→9,10), Line side DAA IC101 and the NCU section to the telephone line.

The analog image data which is received from the telephone line passes through the NCU section and enters line side DAA*

IC100. The signals are changed to digital data in IC101 (5,6) ,IC100(9,10

→5) and IC300. In this case, the image signals from

the telephone line are transmitted serially. Here, the internal equalizer circuit reduces the image signals to a long-distance
receiving level. This is designed to correct the characteristics of the frequency band centered around 3 kHz and maintain a con-
stant receiving sensitivity.

The path is the same as Facsimile Reception.

This is the call signal which is generated the SOC (IC300) and sent to the speaker.

 DAA : Direct Access Arrangement

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KX-MB2000RUB/KX-MB2000RUW/KX-MB2020RUB/KX-MB2020RUW/KX-MB2030RUB/KX-MB2030RUW

Composed of ITS circuit and NCU circuit.

The analog section works as an interface between the telephone line.
DAA control ITS circuit and NCU circuit. 
DAA control signals are output from Soc IC300.

[NCU]: Network Control Unit the NCU comprises of the following; DC loop forming circuit to connect with the telephone line;
Switching circuit for other interconnected telephones; Bell detection circuit; Remote fax activation circuit.
Refer to NCU Section (KX-MB2020/2030 ONLY) (P.28) for the details.

RING

ARXD

ATXD

BTXD

BRXD

IC200

IC100

IC101

EXTRLY

T

R

T

R

SP(+)

SP(-)

HS_MIC(+)

HS_MIC(+)

HS_SP(+)
HS_SP(-)

15

5

6

5

6

10

9

8

9

15

1

16

14

12

1

3

13

4

5

10

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KX-MB2020RU / KX-MB2030RU: MAIN BOARD BLOCK DIAGRAM

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KX-MB2000RUB/KX-MB2000RUW/KX-MB2020RUB/KX-MB2020RUW/KX-MB2030RUB/KX-MB2030RUW

This section is the interface between the telephone line and external telephone. It is composed of an EXT. TEL line relay (RLY100),
bell detection circuit, TAM interface circuit and line amplifier.

1. Circuit Operation

Normally, this relay switches to the external telephone side and switches to the open side while OFF-HOOK.
IC300 (R33) High Level

→Q100 ON→RLY100 (ON)

1. Circuit Operation

The signal waveform is indicated below. The bell signal input  to  IC101 and ring detected signal output from pin 15 of IC100.
IC300 monitor this signal and judged as bell.
TEL LINE

→IC101 (8,9 - 5,6)→IC100 (9,10 - 15)→IC300(AA25)