la4815m Sanyo Semiconductor Corporation, la4815m Datasheet - Page 8

• Manufacturer Part Number: la4815m
• Description: Monaural Power Amplifier
• Manufacturer: Sanyo Semiconductor Corporation

5. Popping noise reduction during power-off
6. Input coupling capacitor (Cin)
7. Output coupling capacitor (Cout)
8. Output phase compensation capacitor (Cosc)
9. Power supply capacitor (CV CC )
The power supply line can be directly controlled ON and OFF without using the mute function. However, when using
a high supply voltage, the shock noise and aftersound during power-off tends to worsen. One method of coping with
this is to connect a capacitor between Pin 6 (V CC ) and Pin 7 (MUTE) as shown in Fig. 9 so that the auto mute function
operates during power-off.
Recommended value = 1μF
Cin is an input coupling capacitor, and is used for DC cutting. However, this capacitor is also used to improve the ripple
rejection ratio, which changes according to the capacitance value (recommended value = 1μF). In addition, this
capacitor also affects the transient response characteristics during power-on and when mute is canceled, so the constant
should be set in consideration of these characteristics.
Design reference value = approximately 0.33 to 3.3μF
Cout is an output coupling capacitor used for DC cutting. However, this capacitor, Cout, in combination with load
impedance R L forms a high-pass filter and attenuates the low frequency signal. Take into account the cutoff frequency
when determining the capacitance value. In addition, normally a chemical capacitor is used for this capacitor, but the
capacitance value of chemical capacitors decreases at low temperatures, so the value should be set in accordance with
this characteristic.
The cutoff frequency is expressed by the following formula.
fc = 1/(2π × R L × Cout)
The Cosc capacitor is used to prevent output oscillation. Use a ceramic capacitor (recommended value = 0.1μF) with
good high frequency characteristics, and locate this capacitor as close to the IC as possible.
The CV CC capacitor is used to suppress the ripple component of the power supply line. Normally a chemical capacitor
(recommended value = 10μF) is used for this capacitor. However, chemical capacitors have poor high frequency
characteristics, so when using a CPU, DSP or other IC that generates digital noise in the set, it is recommended that a
power supply bypass capacitor (ceramic capacitor, recommended value = approximately 0.1μF) be added to reject
high-frequency components. Locate this bypass capacitor as close to the IC as possible.
• Ripple rejection ratio : Increasing the capacitance value increases the rate, and reducing the value reduces the rate.
• Rise response speed : Increasing the capacitance value reduces the speed, and reducing the value increases the
• Popping noise : Increasing the capacitance value reduces the noise, and reducing the value increases the noise.
speed.
CV CC
+
LA4815M
Figure 9
Cmt
1μF
+
6
7
V CC
MUTE
LA4815M
No.A1373-8/14