LA4460N, 4461N
No.2660–6/12
Continued from preceding page.
· Soft clipping characteristics are accomplished by lowering the open loop voltage gain and reducing the amount of
feedback to reduce undesired radiation to radio frequency circuits and to increase the circuit stability. The distortion
deterioration resulted from the decreased amount of feedback will be avoided by using a unique distortion reduction
circuit, thus 0.1% typ. will be assured.
· A capacitor for oscillation compensation is included inside the IC as a method of reducing external parts.
The capacitance is 30pF and this determines the cutoff frequency f
H
(–3dB point) of the high range (f
H
≈
30kHz).
· To reduce variations of the voltage gain, a feedback resistor R
NF
is also built-in, and the voltage gain is fixed to 51dB.
However the voltage gain will be decreased by adding a resistor R
NF
’, where the R
NF
’ is the resistor to be connected to
the pin 4. (In the Sample Application Circuit 2, the gain adjustment will be made with the resistor connected to either
pin 4 or 5.)
· Two ground pin terminals are provided, one for the preamplifier and the other for the power amplifier. Accordingly,
stability of the IC is increased, especially, distortion deterioration phenomenon caused by increased signal source
impedance Rg is improved and a flat response will be obtained.
· An overvoltage protector circuit is included to protect the IC from damage when a surge voltage is applied to the power
line. The overvoltage is set at 25V, however, the circuit can resist 50V for giant pulse surge of 200ms.
· For OCL connections, a DC short-circuit protection circuit is required. Therefore a grounding protection circuit which
endures against the OUTPUT-GND short-circuit is provided. Since consideration is given to the offset caused by short-
circuit or releasing the short-circuit both the speaker and the IC can be protected.
· When adding an audio muting circuit in each application circuit, refer to the illustration below.
6V
≤
V
M
≤
V
CC
Recommended V
M
=9V
ATT=38dB (Rg=600
)
Flow-in current I
O
is calculated as shown below.
I
O
=V
M
– V
BE
R
1
To increase muting attenuation, connect a resistor of 5.6k
in series with the input circuit, then the attenuation will be
increased to 55dB. It should be noted that adding an input capacitor will increase pop noise when the AC muting is
operated. Pop noise can be reduced by increasing the value of R
1
and C
1
.
R
NF
=53
, R
f
=20k
when R
NF
’=0
VG=20log R
when R
NF
’ is used
VG=20log (dB)
R
NF
R
R
NF
+R
NF
’
2