LA4278 데이터 시트보기 (PDF) - SANYO -> Panasonic
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LA4278 Datasheet PDF : 6 Pages
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LA4278
Description of External Parts
C1, C5: Feedback capacitors
Decreasing the capacitance value lowers the low frequency response. Increasing the capacitance value makes the
starting time later.
C2, C4: Input capacitors
Because the DC potential of the input pin is not zero, this capacitor can not be omitted. Decreasing the capacitance
value to an extremely low level lowers the low frequency response.
C3: Ripple filter capacitor
Decreasing the capacitance value reduces ripple rejection. This capacitor also affects the starting time; decreasing
the capacitance value makes the starting time earlier.
C6, C9: Output capacitors
Decreasing the capacitance value causes insufficient power at low frequencies.
C7, C10: Oscillation blocking capacitors
Decreasing the capacitance value causes oscillation to occur easily. Use a mylar film capacitor that has good high
frequency response and temperature characteristics. The use of an electrolytic capacitor or a ceramic capacitor may
cause oscillation to occur at low temperatures.
C8: Power capacitor
Decreasing the capacitance value causes ripple to occur easily. Locating this capacitor at a distance from the IC or
removing this capacitor may cause oscillation to occur.
R1: Muting resistor
Refer to supplementary discussion “External Muting.”
R2, R3: Resistors connected in series with oscillation blocking capacitor
These prevent phase shift in conjunction with the oscillation blocking capacitor so that oscillation does not easily
occur. There is an optimal value for the resistor; increasing or decreasing the resistance causes oscillation to occur
easily.
External Muting
• Pull down the electric potential of the ripple filter pin (pin 3).
Muting becomes possible by inserting the discharge resistor R3 between pin 3
and GND. If the resistance value of R3 is too low, a popping noise is generated; if
the resistance value is too high, the muting effect is reduced. (A value of 750 Ω is
recommended for R3.)
IN1
Filter
PRE GND
2
3
4
+
C3
R3
Mute SW
Voltage Gain
The voltage gain is fixed at 40dB by the ratio of the 30 kΩ and 300 Ω
internal resistors. Therefore, it is not possible to use this IC with a
voltage gain greater than 40 dB. Although it is possible to use this IC
with a voltage gain of less than 40 dB by adding a feedback resistor
(RNF) and external resistors (R) as shown in the diagram, doing so
causes oscillation to occur easily. Therefore, do not use this IC with a
voltage gain of 30dB or less.
RNF
Rf 30 kΩ
IN1/2
5
(2)
NF1/2
6
(1)
OUT1/2
7
(10)
C2/C4
R
C1/C5
+
+
+
C6/C9
RL
C7/C10
R2/R3
No. 7096-3/6
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