LA4906 查看數據表（PDF） - SANYO -> Panasonic
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LA4906 Datasheet PDF : 10 Pages
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LA4906
Technologies for Increased Efficiency Used in the LA4906
• Signal-following switching technique
The LA4906 uses a switching regulator for the power supply for the
amplifier output stage. The LA4906 significantly reduces power
dissipation by having the switching regulator output voltage follow
the signal. Also, the LA4906 restricts the number of switching
regulators required to just one circuit even though it implements a
BTL 2-channel amplifier by using the switching regulator in
combination with the nonlinear amplifier described below. (See
Figure 1.)
Regulator
output
Nonlinear
amplifier
Amplifier
output
stage
• Nonlinear amplifier
The LA4906 adopts a nonlinear amplifier, which has the nonlinear
characteristics shown in Figure 2, in the signal system. The LA4906
dispenses with the lower side switching regulator by using a low 2 V
as the midpoint voltage instead of the 1/2 VCC used in normal
amplifiers.
This nonlinear amplifier is basically formed from a differential
amplifier that has a symmetrical negative feedback circuit. Although
the BTL output stage positive and reverse phase output waveforms
have a half-wave waveform that, when referenced to ground, is
expanded and compressed as shown in Figure 3, the combined
output waveform at the load terminals is identical to that of earlier
products.
Regulator output (point C)
Loss in the output
transistor
Figure 1 Overview Block Diagram
Figure 2 Nonlinear Amplifier
Input/Output Characteristics
Positive phase
output (point A)
Center point
Ground
Reverse phase
output (point B)
Center point
Ground
Regulator output (point C)
RL = 4 Ω
f = 1 kHz
Rg = 600 Ω
With both channels
driven.
Calculated at Pd =
VCC × ICC – 2 PO
Earlier SANYO
products (class
B amplifiers)
Waveform between
the outputs
(Between A and B)
Figure 3 Output Waveforms
High-efficiency
LA4906
Output power, PO – W
Figure 4
No. 5714-3/10
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