Unregulated Always On Voltages; Ref; Dc In - Battery Switching - Sony DSC-S75 Training Manual

Unregulated always ON voltages

The always-on voltage is fed to all
circuits via four fuses ? F1 ~ F4. Each
fuse supplies a different section of
IC001 and its respective external
switching circuit.
+10V, +15V, -10V Supplies
The circuit supplying these voltages
is unique: one of the secondary
windings is in series with the +4.9V
output from Q007. See Figure 5-2. It
operates as follows:
1. The primary winding of the
transformer is switched by Q005
to provide an ac voltage to the
primary. Q005 is powered by Vcc-B.
2. The turn ratio of the secondary +10V and +15V winding can provide only +5V and +10V. To get the additional
5 volts, the common leg of the secondary winding is not connected to ground but to the +4.9V line from Q007.
This causes the output from this secondary winding to increase by 4.9V.
V REF
This output line from Control IC001 provides a very stable 1.5 reference voltage to many of the voltage regulators
in the power supply.
DC IN – Battery Switching
AC Adapter Connected
See Figure 5-1.
•
The ac adapter directly supplies the camera with power when it is connected. Q002 provides a fast charge
(initial charge) to the battery if the battery charge is low.
•
Q003, Q004 and D003 charges the battery with a slow initial charge (current limiting)
•
Once the battery has charged up a little, switch Q003 / Q004 opens and Q002 closes. This provides the
battery with a faster charge.
•
When the battery has fully charged, switch Q002 opens and the battery is isolated from the ac adapter
power.
AC adapter Not Connected
See Figure 5-1.
•
The battery supplies power to fuses F001 ~ F004 via switch Q003/Q004 and D003.
Q005
VCC-B
SW.
FROM
IC001
FIGURE 5-2 - +10V, +15V,-10.5V DIAGRAM
11
5. DSC-S75 and DSC-S85 Power Supply
PRI
4.9V FROM
Q007
-10.5V
+
+15V
+
+10V
+
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