APPLICATION INFORMATION AND APPLICATION METHOD
1. ADJUSTMENT OF VOLTAGE GAIN
The voltage gain Gv is obtained as follows by R1, R2 and Rf in Fig. 1.
GV = 20 log
When Rf=0, Gv=56dB(Typ.)
When Rf=82 , Gv=45dB(Typ.)
By increasing Rf, reduction of Gv is Possible. However, since the feedback
increase is liable to produce oscillation, it is recommended to use this at 40dB or over.
2. THERMAL SHUT-DOWN CIRCUIT
The thermal shut-down circuit is built in for the purpose of preventing the destruction of IC due to the abnormal temperature rise
when the heat radiation is insufficient. The operation temperature is set at radiation Fin temperature 175 (Typ.) At this temperature
or over the bias is interrupted to prevent the destruction of IC.
3. INPUT STAGE
The input circuit of this IC is as shown in Fig. 2. PNP TR:Q1 is provided in
the input circuit so as to make its usage possible without the input coupling
capacitor. However, at pins and , max 60mV offset voltage is produced.
Application after checking volume slide noise is recommended.
For cutting the volume slide noise, insert the input capacitor :
CIN in series to interrupt the DC compornent.
4. OSCILLATION PREVENTIVE MEASURES
For oscillation preventive capacitor C6 and C7 between
the output terminal and GND, it is recommended to use
polyester film capacitor having good characteristics for
temperature and for high frequency.
Since the characteristics of the capacitor is liable to be
influenced by the temperature, use this capacitor after the temperature
test to check the oscillation allowance. In addition, as the position
of the electrolytic capacitor has a remarkable influence on the oscillation,
connect C10 to VCC at the nearest possible position from power GND.
At using this application with the voltage gain reduced, oscillation is liable
to be produced. Apply the capacitor after checking enough for its capacity,
type and mounting position.As the oscillation allowance varies according to the printed
pattern layout, the standard printd board of KEC is recommended to be referred to for design it.
5. INPUT VOLTAGE
When the excessive signal is input, turning-up is produced in the clip waveform.
The turning-up point is VIN=300mVrms(Typ.) : VCC=9V, RL=4 , f=1kHz : Enough care must be taken for this phenomenon.
1994. 10. 31
Revision No : 0