LA3401 View Datasheet(PDF) - SANYO -> Panasonic
Part Name
Description
Manufacturer
LA3401 Datasheet PDF : 15 Pages
| |||
LA3401
How to externd the dynamic range of the post amplifier
In the Sample Application Circuit of the LA3401 the dynamic range of the post amplifier is extended by connecting
resistors R12, R13 across the virtual GND points (pins 6, 7) of the post amplifier and GND as shown in Fig. 13 to set
the output (pins 5, 8) DC voltages to an adequate value.
The DC voltages on pins 5, 8 are obtained as follows :
3.3
RB + R1
RB
=3.3
1+
R1
RB
3.3
RB + R2
RB
=3.3
1+
R2
RB
The upper and lower loss voltages of the post amplifier output
are approximately 2V and 0.5V respectively as shown in Fig.
14. With these loss voltages considered, the voltages on pins
5, 8 are set.
In the Sample Application Circuit the voltages on pins 5, 8 are
set to 6V and the maximum output voltage is obtained at
VCC=13V.
The Sample Application Circuit provides the reduced
voltage characteristic at approximately 9V. If the reduced
voltage characteristic at approximately 6V is required,
remove R12, R13 shown in the Sample Application
Circuit. Then, the output (pins 5, 8) DC voltages becomes
approximately 3.3V and the reduced voltage characteristic
becomes as shown in Fig. 15. Fig. 15 shows the THD vs.
VCC characteristic, but other characteristics such as
separation are also available at VCC=6V by removing
R12, R13.
Low-pass filter
Fig. 16 shows a sample circuit configuration where an
LC filter is used as the low-pass filter and Fig. 17 shows
a sample characteristic of this filter. As compared with the LPF (BL-13) in the Sample Applicatin Circuit, the use of
this filter makes the attenuation less at 19kHz, 38kHz : therefore, carrier leak at the LPF output causes the stereo
distortion and separation characteristic to get worse than specified in the Operating Characteristics. For the stereo
distortion, the BL-13 provides approximately 0.02%, while the LC filter provides approximately 0.5%.
No.1868–10/15
Share Link: 