279

Audio ICs

BA3430S / BA3430F / BA3430FS

FOperation notes

(1)

Application circuit

The application circuit is an example of a circuit we re-

commend, however, before using it further examination

of characteristics and patent issues is necessary. If any

of the values of the external connections are changed, be

sure to take into consideration both the quiescent and

transient characteristics of the IC and external compo-

nents, and also deviations in the characteristics.

(2)

Resistor values for switch pins

To prevent incorrect operation of the switch pins, use a

3k to 10k

Ω resistor at Pins 20 and 23, and a 2k to 22kΩ

resistor at Pins 21 and 22.

(3)

Capacitors for switch pins

The capacitors connected to Pins 20 and 23 are for pre-

venting incorrect operation of the mute detection circuit.

Without these capacitors, the switching sound which oc-

curs when the internal switches are switched will cause

the mute detection output pin (Pin 24) to go low even

when there is no signal, and this error will continue

throughout the mute detection time. If a short mute detec-

tion time is set and the error can be tolerated, the capaci-

tors can be omitted. The capacitors at Pins 21 and 22 are

for preventing a “pop” sound in the audio signal. If the pop

sound is muted at a latter stage, the capacitors can be

omitted. Naturally, the mute detection circuit will still op-

erate correctly if they are omitted.

(4)

Song detection output / input level

The song detection output / input level can be set with the

resistors connected to Pins 3 and 4. Small values for

these resistors will create a large amplifier gain, lowering

the song detection output / input level. The song detec-

tion output / input level in the application circuit is

*93.5dBV (5kHz) during playback and *81dBV

(10kHz) during fast forward.

(5)

Frequency characteristics of sensitivity switch am-

plifier

The low cutoff frequency during playback can be set with

the capacitor and resistor values of Pin 3. The low cutoff

frequency during fast forward can be set with the capaci-

tor and resistor values of Pin 4, and the high cutoff fre-

quency can be set with the capacitor connected to Pin 5

and the internal resistor.

(6)

Song detection time

The song detection time can be set with the capacitor

connected to Pin 2. If the time is too short, short noise sig-

nals will also cause the circuit to operate. Set the time as

long as possible.

(7)

Mute detection time

The mute detection time is proportional to the product of

the capacitor and resistor between the supply voltage

and Pin 2. Taking into consideration the allowed IC cur-

rent, select a resistor which is 22k

Ω or more.