ICD-MS1 (serv.man2) - Sony Audio Service Manual (repair manual). Page 8

Copying is strictly prohibited 

8

 

 
VOLTAGE DETECTOR IC521 and Q521 have the function of over-discharge protection of battery. When the power input voltage at pin-3 [IN] of the VOLTAGE DETECTOR 
IC521 has decreased to about 0.6 [V] (output voltage from battery is about 1.2 [V]) or less, the current flowing into the unit is limited by stopping the CE (chip enable) voltage to 
the power controller IC522 and the +3.3 [V] regulator IC524 in order to protect battery from over-discharging. 
 

2

3

1

2

3

3

41

1

Q521 2/2 is turned OFF when Q521 1/2 is turned 
OFF so that the CE power supply to IC522 and 
IC524 is stopped.

0 V when UN REG 2.5 [V] has decreased 
to about 1.2 V or less

IN

GND

OUT

UN REG 2.5[V]

R526

C521

R525

R527

VOLTAGE
DETECT

Q521
1/2

R521

R522

R523

Q521
2/2

DC-DC CONVERTER
CONTROL

TO
IC522
POWER CONTROL

TO
IC522
IC524

[CE]

[CE]

[S POWER]

FROM
IC722

R528

IC521

 

 

 

Fig. 2-2    Over-discharge protection circuit