Description of External Parts
C1 (C2)
Feedback capacitor
The low-range cut-off frequency is determined by the following formula:
fL =1/(2 π C1vRf), fL: Low-range cut-off frequency
Rf: Feedback resistor
(50
embedded + Rf externally connected)
The frequency, however, affects the starting time in conjuction with
decoupling capacitors. Therefore, it is necessary to determine it after a
full review of the required low-frequency range and other similar
conditions.
C3 (C4)
Bootstrap capacitor
The output at low frequencies depends on this capacitor. If the capacity
is decreased, the output at low frequencies goes lower. 47 F min. is
required.
C5 (C6)
Oscillation preventing capacitor
Use polyester film capacitor which is good in temperature characteristic
and frequency characteristic. Aluminum electrolytic capacitor or
ceramic capacitor causes oscillation at low temperatures.
C7 (C8)
Output capacitor
The low-range cut-off frequency is determined by the following formula.
fL =1/(2π C7vRL), fL: Low-range cut-off frequency
RL:Load resistance
When using bridge-connected, double the capacitance to obtain
equivalent low-range frequency characteristics to those in a 2-channel
application.
C9
Decoupling capacitor
Used for the ripple filter. Since the rejection effect is saturated at a
certain capacity, it is meaningless to increase the capacity more than
needed.
This capacitor, being also used for the time constant of the muting
circuit, affects the starting time.
C10
Power source capacitor
Application Circuits
1.
Voltage gain adjustment
.
Stereo
The voltage gain depends on built-in-resistors R1 (R2), R3 (R4) as follows:
VG = 20 log
R3 (R4)
R1 (R2)
[dB]
If the IC is used at a voltage gain less than this, the following
equation with Rf added applies.
VG = 20 log
R3 (R4)
R1 (R2) + Rf
[dB]
where R1 (R2) = 50
typ.,
R3 (R4) = 10 k
typ.
.
Bridge
The following shows the bridge amplifier configuration, where ch1 operates as a non-inverting amplifier and ch2 as an inverting
amplifier.
LA4183
No.887-4/12