la4815vh Sanyo Semiconductor Corporation, la4815vh Datasheet - Page 6

• Manufacturer Part Number: la4815vh
• Description: Monaural Power Amplifier
• Manufacturer: Sanyo Semiconductor Corporation

Notes on Using the IC
1. Voltage gain settings (Pins 4 and 11)
2. Signal source impedance : rg
The voltage gain of the power amplifier is fixed by the internal resistors.
Note that the voltage gain can be changed using two resistors. (See Fig. 1)
In addition, the voltage gain can also be lowered to approximately 20dB (when using 5V or 6V power supply) by an
application such as shown in Fig. 2 below.
However, note that using this method to greatly lower the voltage gain deteriorates the characteristics, so the voltage
gain should be lowered only to approximately 20dB. In addition, when using a high supply voltage (7V or more), the
clipped waveform may invert, so this voltage gain reduction method must not be used in these cases.
As mentioned above, since the input coupling capacitor Cin affects the ripple rejection ratio, the signal source
impedance value rg, which is associated with this capacitor, also affects the ripple rejection ratio, so rg should be as
small as possible. Therefore, when attenuating the signal at the Cin front end as shown in Fig. 4, the constants should be
set in consideration of these characteristics. Using the smallest resistor Rg1 value possible is recommended.
In addition, when setting the signal level, the voltage gain should be set on the LA4815VH side and the input front-end
should be configured using only the input coupling capacitor, Cin, as shown in Fig. 5 in order to maximize the ripple
rejection ratio.
• Pins 4 and 11 be left open : Approximately 26dB
• Pins 4 and 11 connected to GND : Approximately 39.5dB
• Voltage gain setting : According to the resistor connected between Pin 4 and Pin 12 (GND1)
• Output DC voltage setting : According to the resistor connected between Pin 11 and Pin 12 (GND1)
• Voltage gain setting : According to the resistor connected between Pin 4 and Pin 1 (OUT)
• Output DC voltage setting : According to the resistor connected between Pin 11 and Pin 2 (V CC )
other IC
other IC
* Voltage gain = 20log (20 × (625 + Rvg1)/(125 + Rvg1))
* Rvg1 = Rvg2 must be satisfied.
* Voltage gain = 20log (20 × (125 + Rvg3)/(10,125 + Rvg3))
* Set the resistor values so that the Pin 5 (OUT) DC voltage is approximately half the supply voltage.
ro
ro
OUT
OUT
OUT
Example : When Rvg3 = 10kΩ, Rvg4 = 22kΩ (when V CC = 6V)
1
LA4815VH
V CC
2
Figure 1
Figure 5
Cin
GND1 GAIN1
Figure 4
12
Rg2
Rvg2
GAIN2
13
11
4
Rg1
Rvg1
IN
Cin
LA4815VH
13
LA4815VH
IN
LA4815VH
OUT
1
LA4815VH
rg
V CC
2
Cin
Figure 2
GND1 GAIN1
12
Figure 3
IN
Rvg3
13
GAIN2
11
4
Pre-Amp
100kΩ
Rvg4
+
-
Vbias
No.A1374-6/15