la4265 Sanyo Semiconductor Corporation, la4265 Datasheet - Page 3

• Manufacturer Part Number: la4265
• Description: 3.5w Monaural Power Amplifier
• Manufacturer: Sanyo Semiconductor Corporation

Description of External Parts
Note for Changing Voltage Gain
External Muting
Measure against Fold-back of Output Waveform
C1 (330pF) : Input short capacitor
C2 (100 F) : Feedback capacitor
C3 (0.1 F
polyester film Decreasing the capacitance value causes oscillation to occur easily. Use a polyester film capacitor that is
capacitor)
C4 (470 F) : Output capacitor
C5 (470 F) : Power capacitor
C6 (100 F) : Ripple filter capacitor
R1 (100k ) : Input bias resistor
R2 (3.3 )
The voltage gain can be reduced by adding an external resistor (R
characteristic curve). However, it should be noted that various characteristics are also changed (THD-VG, V
VG). The voltage gain must not be reduced to be less than 30dB. Since the frequency response is extended and oscillation
is liable to occur when the voltage gain is reduced, high-cut must be made as required. (High-cut is made by connecting
a capacitor of approximately 30pF across pins (6) and (7).)
If external muting is required, make the circuit as shown on next page. In this case, the pop noise is similar to that which
occurs at the time of power switch ON/OFF. If the value of the series resistor is decreased, more pop noise is heard at the
time of attack ; if increased, muting is hard to work.
Since the input pin is zero-biased, the circuit may be saturated at an overinput, causing a part of the output waveform to
be folded back (e. g. when the peak input voltage exceeds 600mV). In such a case, the fold-back of the waveform can be
prevented by using the built-in diode (also can be prevented by using an external diode). When the built-in diode is used,
a resistor must be connected in series with the input pin to cause the diode to conduct no overcurrent (10mA or less).
: Oscillation blocking capacitor
: Resistor connected in series with oscillation blocking capacitor
good in high frequency response and temperature characteristic. The use of an electrolytic capacitor may
Reduces the high frequency noise when the input impedance is increased. Not required when the input
impedance is decreased.
Decreasing the capacitance value lowers the low frequency response. Increasing the capacitance value
makes the starting time later.
cause oscillation to occur at low temperatures.
Decreasing the capacitance value causes insufficient power at low frequencies.
Decreasing the capacitance value causes ripple to occur easily. Locating at a distance from the IC or
removing this capacitor may cause oscillation to occur.
Decreasing the capacitance value excessively or removing this capacitor causes ripple to occur. However,
increasing the capacitance value does not always cause ripple to be reduced. Decreasing the capacitance
value makes the starting time earlier.
Determines the bias (bias of zero potential) to be applied to the input pin and the input impedance. Not
required if a variable resistor is also used as this resistor.
Prevents phase shift attributable to the oscillation blocking capacitor so that oscillation is hard to occur.
LA4265
NF
) in series with the feedback capacitor. (See VG · R
NO
No.1463–3/8
-VG, Vro-
NF