AN7195Z

ICs for Audio Common Use

8

s Technical Information (continued)

[2] Application note (continued)

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. 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 k

Ω or less of signal source impedance R

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.

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.

For that reason, abnormal sound due to waveform distortion at rising and falling of the circuit is not released.

4.7 k

Ω

30 k

Ω

200

Ω

6

11

400

Ω

15

µA

0.01

µF

1

µF

15

µA

Attenuator

To power

Input signal

2.2

Ω

0.1

µF

2,4

1

13,15

3,14

To speaker

Figure 2