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12
LC-13B2H/M
LC-15B2H/M
LC-20B2H/M
LC-15B2H/M
LC-20B2H/M
3-7. Power supply circuit
5V, 3.3V, 9V, 12V, 13V, 29V, 31V and -8V are outputted.
The DC power supply from the AC adapter is inputted to the inverter circuit, audio IC, power supply circuit,
microcomputer IC (IC2001) and power supply IC.
In the power supply circuit, the DC power supply from the AC adapter is inputted to the transformer (T3701).
The transformer outputs the voltages (31V, 29V, 5V and -8V) smoothed in the diode and electrolytic capacitor
connected to the output terminal from DC power supply input.
The DC power supply from the AC adapter is inputted to the inverter circuit, audio IC, power supply circuit,
microcomputer IC (IC2001) and power supply IC.
In the power supply circuit, the DC power supply from the AC adapter is inputted to the transformer (T3701).
The transformer outputs the voltages (31V, 29V, 5V and -8V) smoothed in the diode and electrolytic capacitor
connected to the output terminal from DC power supply input.
»
Output voltage circuits
(1) BTU5V and B5V circuit
The output from pin (7) of the transformer (T3701) is rectified and smoothed in D3707, C3720, C3721
and C3722 to supply BTU5V. BTU5V is smoothed in L3702, C3727 and C3728 to supply stable B5V.
and C3722 to supply BTU5V. BTU5V is smoothed in L3702, C3727 and C3728 to supply stable B5V.
(2) 5V (for microcomputer power supply) circuit
The DC power supply from the AC adapter is inputted to pin (1) of the regulator IC (IC701) after passing
through the buffer transistor and stable 5V is supplied from pin (3).
through the buffer transistor and stable 5V is supplied from pin (3).
(3) 3.3V circuit
B5V is supplied to pin (1) of the regulator IC (IC701) and stable 3.3V is supplied from pin (3).
(4) 9V circuit
The output from pin (8) of the transformer (T3701) is rectified and smoothed in D3706, C3718, C3717
and L3703 to supply 9V.
and L3703 to supply 9V.
(5) 12V circuit
The DC power supply from the AC adapter is rectified and smoothed in C3710, C3700 and Q3700 to
supply stable 12V.
supply stable 12V.
(6) 13V circuit
The DC power supply from the AC adapter is rectified and smoothed using the electrolytic capacitor etc.
and supplied to each circuit.
and supplied to each circuit.
(7) 29V and 31V circuit
The output from pin (10) of the transformer (T3701) is rectified and smoothed in D3704, C3714 and
C3715 and stable 29V and 31V are supplied using the operational amplifier IC (IC3702), Q3707, Q3704,
Q3705, Q3706 and D3709.
C3715 and stable 29V and 31V are supplied using the operational amplifier IC (IC3702), Q3707, Q3704,
Q3705, Q3706 and D3709.
(8) -8V circuit
The output from pin (6) of the transformer (T3701) is rectified and smoothed in D3708, C3724, C3725
and L3704 to supply stable -8V.
and L3704 to supply stable -8V.
Fig. 3-9. Power supply circuit
DC IN
DC13V
(12V for
13/15)
DC/DC
T3701
IC3701
Q3700
Q3701
Q3702
Q3701
Q3702
38V
16V
9V
5V
-8V
REGULATOR
IC3702
31V
Q3707
29V
Q3704
14V
Q3705
8V
Q3706
3.3V
IC701
Regulator (supplying 5V for microcomputer)
Inverter circuit
Audio amplifier IC
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