ba3430f ROHM Co. Ltd., ba3430f Datasheet - Page 11

• Manufacturer Part Number: ba3430f
• Description: Stereo Pre-amplifiers With Mute Detection Circuits For Car Stereos
• Manufacturer: ROHM Co. Ltd.

FOperation notes
(1)
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)
To prevent incorrect operation of the switch pins, use a
3k to 10k resistor at Pins 20 and 23, and a 2k to 22k
resistor at Pins 21 and 22.
(3)
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.
Audio ICs
Application circuit
Resistor values for switch pins
Capacitors for switch pins
(4)
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)
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)
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)
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 or more.
Song detection output / input level
Frequency characteristics of sensitivity switch am-
Song detection time
Mute detection time
BA3430S / BA3430F / BA3430FS
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