Scp - Sony DSC-S75 Training Manual

Camera +15V Line
The circuit supplying Camera 15V is somewhat unique: it actually produces only 10 volts. To get a 15 volt output,
the cold leg of its secondary transformer winding is connected to the A4.9V line instead of to ground. This boots
the 10 volts to 15 volts.
AC Adapter – Battery Switching
Ac Adapter Connected
•
The ac adapter supplies the camera directly with power when it is connected to the camera. Q403/Q404
provides an initial charge to the battery and if it needs further charging, fast charge transistors Q401/Q402
turn on.
•
Switch Q401/Q402 provides the battery with a fast charge when the battery charge is low. The switch is
controlled by the FAST CH line from SY-68 board via CN701/pin 37.
•
After the battery has fully charged, switch Q401/Q402 opens and the battery is isolated from the ac adapter.
Ac adapter Not Connected
•
The battery supplies power to the unregulated supply lines via switch Q403 / Q404 / D403 and fuses F401
through F404.
•
Switch Q403/Q404 remains closed until the battery is nearly discharged, at which point the switch opens,
cutting off power to the switching regulators.
Unregulated Always ON Voltages
The unregulated always-on voltage is fed to all circuits via four fuses - F401 through F404. Each fuse supplies
a different section of IC001 and its respective external switching circuits. Another always-on line provides standby
power the Front Control IC102 when the camera is disconnected from the ac adapter.
IC001 Control Lines
SYS DD ON
This is the master switch that turns the
DC CONTROL IC ON/OFF. The line must
be HIGH (3.2v) for the IC to operate. It is
controlled by FRONT CONTROL IC102.
SCP (Short Circuit Protection)
This is a short circuit protection line that
monitors three negative voltage lines
(PANEL -15.3V, CAM -7.5V, and –BLVO)
for short circuits or excessive loads. See
Figure 15-2.
CAM -7.5V
CAM 4.9V
PANEL -15.3V
BLVO -20V
A3.2V
FIGURE 15-2 - F707 SHORT CIRCUIT PROTECTION
37
15. DSC-F707 Power Supply
UNREG 1

SCP

13
NPN
Q017B
NPN
Q017A
NPN
Q001
IC001
DC-CONTROL
IC