AN7195K
s
Technical Information (continued)
[2] Application note (continued)
ICs for Audio Common Use
1
2. Oscillation countermeasures
1) In order to increase the oscillation allowance, connect a capacitor and
a resistor in series between each output terminal and GND as shown
in figure 2.
2) The use of polyester film capacitor having a little fluctuation with
temperature and frequency is recommended as the 0.1
µF
capacitor
for oscillation prevention.
3,14
2,4
13,15
To speaker
0.1
µF
2.2
Ω
Figure 2
3. Input terminal
1) The reference voltage of input terminal is 0 V. When the input signal has a reference voltage other than 0 V
potential, connect a coupling capacitor (of about several
µF)
for DC component cut in series with the input
terminal. Check the low-pass frequency characteristics to determine the capacitor value.
2) 10 kΩ or less of signal source impedance R
g
can reduce the output end noise voltage.
3) The output offset voltage fluctuates when the signal source impedance R
g
is changed. A care must be taken
when using the circuit by directly connecting the volume to the input terminal. In such a case, the use of
coupling capacitor is recommended.
4) If a high frequency signal from tuners enters the input terminal as noise, insert a capacitor of approx. 0.01
µF
between the input terminal and input GND.
When a high frequency signal is inputted, malfunction in protective circuits may occur.
15
µA
15
µA
1
µF
Input signal
0.01
µF
6
4.7 kΩ 11
200
Ω
30 kΩ
400
Ω
Attenuator
To power
Figure 3
4. Ripple filter
1) In order to suppress the fluctuation of supply voltage, connect a capacitor of approx. 33
µF
between RF
terminal (pin12) and GND.
2) Relation between RR (Ripple Rejection Ratio) and a capacitor
The larger the capacitance of the ripple filter is, the better the ripple rejection becomes.
3) Relation between the rise time of circuit and a capacitor
The larger the capacitance of the ripple filter is, the longer the time from the power on (standby high) to the
sound release becomes.
4) The DC voltage of output terminal is approximately the middle point of the ripple filter terminal voltage.
5) The internal circuit of ripple filter terminal is as shown in figure 4 and the charge current is approx. 3 mA to
10 mA.
6) The muting circuit turns on when the ripple filter terminal is V
CC
−
4 V
BE
or less.
For that reason, abnormal sound due to waveform distortion at rising and falling of the circuit is not released.
8
PANASONIC [ PANASONIC SEMICONDUCTOR ]
