TH-K2AT/K2E/K2ET

CIRCUIT DESCRIPTION

Power Supply Circuit

■Charging Circuit

When an external power supply is connected to the DC IN terminal, the constant-current circuit consisting of Q33 and D31 provides a constant current of approx. 110 mA to the Ni- MH battery.

If no external power supply is connected to the DC IN terminal, the constant-current circuit does not function.

IC8

Q36

MPU

2SJ347

BTEMP

THERM

 

■Power Supply Switching Circuit

The voltage supplied through the battery terminal or DC IN terminal is branched in the power supply switching circuit as shown in Fig.10 and then supplied to the required components.

■Battery Type Recognition Circuit

When the battery pack is attached to the transceiver, the battery type is recognized with the T terminal on the transceiver. This battery type recognition activates charging for the Ni-MH battery pack and displaying the battery meter.

-

DCDET

 

 

 

 

DET

 

 

 

 

 

 

Q41

 

 

 

 

 

 

 

T

 

 

 

 

 

 

 

 

 

 

VR1

 

RN2105

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ENC

5MS

5MS SW

 

 

 

BTDET

 

 

 

+

 

 

 

 

 

 

 

 

 

 

 

 

 

 

D35

 

 

 

 

 

BATT TERMINAL

 

 

 

 

RB521S-30

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7.5V Norminal

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PROTECT

 

 

 

 

 

(6.0 - 9.0V)

 

 

 

 

 

 

 

 

 

 

 

 

Q57

 

IC9

 

Q35

 

Q33

 

D33

 

 

RN2105

 

TK11250

 

 

D30

IC1

 

5M

 

2SK1830

 

2SB1184

 

 

CM

 

 

RB521S-30

RB051L-40

TCXO

5C

5C SW

 

AVR

 

DC-IN

 

(Q,R)

 

Q4,5,6

 

 

 

BATT

 

PROTECT

D40,41

 

 

 

5.0V

 

DET

 

PROTECT

 

 

 

 

 

CHARGE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

D31

B

 

 

 

 

 

 

 

 

 

DA221

 

IC5

 

Q53

 

IC12

 

Q37, Q38

 

CONSTANT

 

 

Q30

5MV

RN2701

 

TK11250

 

2SB1184

 

CURRENT

 

D32

 

 

 

 

CUCB

IC6

(Q,R)

 

Q34

 

 

 

 

 

 

 

RB051L-40

IC3,17

 

5R SW

 

 

D48,49

2SC4617(R)

 

 

 

5MV SW

 

AVR

D42,43,46

AF/LAMP

B

2SK1830

CHARGE

PROTECT

D9,14

5R

 

 

5.0V

D47,44

AVR

 

CHARGE

Q16,17

 

 

 

 

 

 

Q22,23,24

 

 

D36

 

 

 

SW

 

 

Q59

 

 

 

AF AMP

 

 

 

 

 

 

 

 

RB521S-30

 

 

 

 

 

 

 

 

 

 

 

 

 

DC IN

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PROTECT

 

 

 

 

 

13.8V Norminal

 

 

Q55

 

 

IC4

 

 

 

(12.0 - 16.0V)

 

 

 

 

 

 

 

 

Q9,10,13

 

CPH3317

 

 

 

XC6202PB

 

 

D80

J2

D8,10

5T

 

 

 

 

52FR

 

 

RB521S-30

 

TH1

5T SW

 

 

 

AVR

 

 

B

 

 

 

 

 

 

IC16

 

 

 

 

 

 

 

PROTECT

 

 

 

 

 

 

11.5V

 

 

 

Q47

 

 

 

 

 

 

 

 

 

Fig. 10 Charging and Power supply switching circuit

Control System

■Reset and Backup Circuit

When power is supplied to the transceiver, the 5M voltage goes “H” as C303 is charged.

A rising edge of the 5M voltage is detected by the voltage detection IC (IC11) and when its output (RESET) goes “H”, the reset status of the MPU is released.

If the supplied voltage to the transceiver is reduced and the 5M voltage falls below the detection voltage of the voltage detection IC (IC10), the MPU detects it by an interrupt processing, backs up data in EEPROM (IC15) and turns the power off.

 

 

 

 

 

IC15

 

Timing chart

 

 

 

 

 

 

 

 

 

 

 

 

 

EEPROM

 

Power

Power

 

 

IC9

5C

 

 

 

ON

OFF

 

D35

 

L63

 

 

 

 

 

5V OUT R244

5M

IC8

5M

5V

 

BATT

IN

 

 

AVR

 

 

MPU

 

 

 

 

 

+

 

 

 

 

 

 

 

R243

 

 

 

 

 

 

 

IC11

 

 

0

 

 

 

C303

IN

OUT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RESET

RESET

5V

 

 

 

 

 

C307

 

 

 

 

 

 

 

 

 

 

 

 

 

IC10

 

 

 

0

 

 

 

 

IN

OUT

INT

 

 

 

 

 

 

 

 

 

INT

5V

 

 

 

 

 

 

 

 

0

 

10

Fig. 11 Reset and Backup circuit