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5

Handset

Charger Unit

Standard:

DECT= (Digital Enhanced Cordless Telecommunications)
GAP= (Generic Access Profile)

Power Source:

Rechargeable Ni-MH battery

AC Adaptor

Number of Channels:

120 Duplex Channels

Frequency Range:

1.88GHz to 1.9GHz

Duplex Procedure:

TDMA (Time Division Multiple Access)

Battery Life, Handset (if batteries are fully charged):

Stand-by: Up to 200 hours (Ni-MH)
Talk: Up to 15 hours (Ni-MH)

Channel Spacing:

1728kHz

Bit rate Spacing:

1152kbit/s

Operating Conditions:

5~40 

°C, 20~80% relative air humidity (dry)

Modulation:

GFSK= (Gaussian Frequency Shift Keying)

RF Transmission Power:

approx. 250mW

Voice Coding:

ADPCM 32 kbit/s

Operation Range:

Up to 300 m outdoors, Up to 50 m indoors

Dimensions (D x W x L): 

123 mm x 45 mm x 23 mm

78 mm x 78 mm x 59 mm

Weight: approx. 

120g

approx. 

108g

6

KX-TCA275RU BLOCK DIAGRAM (HANDSET)

RFmodule
(DECT)

RF 3.0V

Batt

AFE

DSP

MIDI

Receiving

Calls

Making

Calls

D/A

A/D

RF I/F

Decoder

Encoder

BMC

1.8V

ACS0

16

16

16

3.0V

3.0V

3.0V

Flash

(32Mbit)

SRAM
(2Mbit)

Color

LCD

ACS1

ACS2

16

CR16C

3.0V

Peripheral

Backlit

5.0V

PWM

BBIC (SC14428F)

Power

Management

Batt

Keys

Xtal

10.368MH

(US-DECT:
   Low deviation)

UART

JTAG

Charger
Circuit

Charge Current

Charge on/off

Battery
3.6V

Batt

Regulator

RF 3.0V

5.0V

Regulator

3.0V

1.8V

Batt

3.0V

Batt

Tr

Batt

Vib

3.0V

LED(G)

LED(R)

LED(YG)

Tr

Tr

Tr

Charge LED

Key backlit

OP-Amp

H

/

S

J

a

c

k

Mic Bias

Rear

Speaker

Receiver

Mic

H/S

detect

Ant

7

Handset consists of the following ICs as shown in Block Diagram (Handset) (P.6).

• BBIC (Base Band IC): IC3

- All data signals (forming/analyzing ACK or CMD signal)
- All interfaces (ex: Key, Detector Circuit, Charge, LCD, LED, SRAM, Flash ROM)

• SRAM: IC1

- Application data and code are temporarily stored.

• Flash ROM (substitute EEPROM): IC2

- Source program data and temporary user data are stored.

• AMPLIFIER IC: IC5

- Single OP_AMP for SPEAKER

• RF  Module:
• PLL Oscillator
• Detector
• Compress/Expander
• Amplifier for reception
• Amplifier for transmission

When power on the Handset, the voltage is as follows;

BATTERY(3.5 V to 4.2V: Battery+) 

→ Q8 (1.8V) → Q10 (3.0V)

The reset signal is generated with IC3 and Q17.
Power for RF IC (IC601) is generated with IC603.
5.0V for LCD back-light is generated with IC4.
Battery (3.5V to 4.2V) is used for RF Module, Amplifier IC (IC5), Vibrator, DC/DC Converter (IC4).
1.8V is used only for BBIC (IC3).
3.0V is used for BBIC (IC3), LCD, SRAM (IC1), Flash ROM (IC2), Red LED, Green LED, Key back-light.

8

• Charge current is controlled as follows.

• Charge mode is trickle charge.
• Charge current repeats ON and OFF as follows.

• Charge route
• DC+ (6.5V) 

→ IP1 → D1 → R2, R3, R4 and R5 → CHG+ (Charger) → CHG+ (Handset) → L2 → Q2 → D13 → IP101 → Battery

→ GND → R5 → CHG- (Handset) → CHG- (Charger) → GND

"Battery Low" and "Power Down" are detected by BBIC (IC3) which checks the battery voltage.
The detected voltage is as follows;
Battery Low
Battery voltage: V(Batt)   3.5V ± 50mV
The BBIC detects this level and "

" starts flashing.

Power Down
Battery voltage: V(Batt)   3.3V ± 50mV
The BBIC detects this level and power down.

IC3-97pin

Q4

Q3

Q2

Charge ON

Low

OFF

ON

ON

Charge Off

High

ON

OFF

OFF