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9. DAV-C700 Switching Type Power Supply
Power Supply Control
See Figure 9-1 for the control of the power supply stage. In this A/V product there is:
•
A front panel latching master power ON/OFF switch (S901) that applies AC power to the product;
•
5.6V applied to the CPU when the power supply is in the Standby mode; and
•
Voltages output the power supply (not shown) when the CPU is instructed to turn ON the power supply.
Switching
Power Supply
Figure 9-1 - Switching
Power Supply Control
CPU
IC901
Serial to
Parallel
IC902
SW
Q002
AC
Master Pwr
S901
Play
Eject
Remote
Control
Data
5.6V
P Cont 2
M12V
to
Driver
IC401
13V
P Cont 1
There are two power ON commands from CPU IC901 (DVD board) to the switching power supply. P Cont 1
takes the switching power supply out of the Standby mode and into the ON mode. The power supply will output
four voltages (not shown), powering up the unit. Both P Cont 1 and 2 go HIGH when the DVD/CD mode is
requested. The power supply produces an additional voltage of 3.3V in the DVD/CD mode (not shown).
Switching Power Supply Block
Refer to Figure 9-2 for the following power supply block description. Each switching power supply has a
fundamental oscillator/voltage output section and a control section. The oscillator section always uses a high
frequency oscillator (IC901) to feed a small power transformer (T901). The power transformer has multiple
secondary windings to deliver the various voltages the product needs to function.
The control section varies in any switching power supply to meet the product needs. In this product, the switching
power supply must output 5.6Vdc when the unit is plugged in (standby mode) and the remainder of voltages
when the unit is powered ON. This means the switching power supply is partially operational when AC power is
applied.
SW. Q915
STANDBY
D912
SW.
Q907, 9
IC905
ERROR REG.
IC902
SWITCHING
REGULATOR
IC901
SW.
Q901,
Q902
REG.
Q903,
D903
POWER
TRANSFORMER
T901
D902
IC906
IC903
62Vdc
TH901
9.1
Ω
163V
13V
Vcc
20V
STBY = 11V
ON = 20V
STBY = 0V
ON = 5V
5.6V
P CONT 1
13V
27V
P CONT 2
3.3V
6.5V
P CONT 1
PRIM.
SEC.
S901
F901
5A
FIGURE 9-2 - DAV - C700 POWER SUPPLY BLOCK
11/27/01
9.1A124 1416
Содержание STR-DE845
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