BA3308 PDF 데이터시트 : 부품 기능 및 핀배열

부품번호 BA3308
기능 Dual preamplifier with ALC
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BA3308 데이터시트, 핀배열, 회로
Audio ICs
Dual preamplifier with ALC
BA3308 / BA3308F / BA3308FV
The BA3308, BA3308F and BA3308FV are dual preamplifier ICs with built-in ALC circuits, and have been designed for
use in stereo radio-cassette recorders and tape recorders. They come in compact 9-pin SIP (BA3308), 14-pin MF
(BA3308F) and 14-pin SSOP (BS3308FV) packages, and have two record / playback preamplifiers, and an ALC circuit.
The preamplifiers have high gain and low distortion, and can be directly coupled to the tape head without coupling capaci-
tors. This prevents tape head magnetization and “pop” noise generation.
A built-in rectifier means that an ALC circuit with good channel balance and large dynamic range can be constructed
with addition of just an external time constant circuit.
The ICs also include power-on mute circuits that suppress “pop” noise generation.
Stereo radio cassette recorders, cassette decks and
home stereo systems and music centers
1) Built-in ALC rectifier diode.
2) Wide operating power supply voltage range (VCC =
4.5V to 14V).
3) Low current dissipation (IQ = 3.5mV).
4) High gain (GVO = 80dB).
5) Low distortion (THD = 0.1%).
6) Low noise (VNIN = 1µVrms)
7) Input coupling capacitors and not necessary.
8) Good ALC channel balance.
9) Power-on mute circuit.
10) ALC dynamic range can be varied by the addition
of an external input resistor.
FAbsolute maximum ratings (Ta = 25_C)
FRecommended operating conditions (Ta = 25_C)

BA3308 pdf, 반도체, 판매, 대치품
Audio ICs
FTotal application circuit
BA3308 / BA3308F / BA3308FV
FCircuit operation
(1) Recording
(1) Recording amplifier (See Fig. 5)
The channel 1 and 2 amplifier input stages of the BA3308
(pins 8 and 2) can be direct-coupled, and the input cou-
pling capacitors C1 and C2 are not particularly required.
The voltage gain of the recording amplifier is given by GV
= R5 / R3, but as a “pop” noise is generated when power
is applied, (see “operation notes”), use the time constant
circuit values given for C3 and R3 (C4 and R4) in the ap-
plication example circuit diagram, or values close to
these, and adjust the voltage gain with R5 (R6). R5 (R6) is
also the DC bias feedback resistor, and is connected be-
tween pin 3 (7), and the output capacitor C5 (C6).
(2) ALC (See Fig. 6)
The BA3308 includes a signal rectifier block and elec-
tronic potentiometers required for the ALC. In the signal
rectifier block, a comparator compares the DC output
voltage component of the output stage signal (pins 3 and
7) to a voltage of 4.5VF (1VF is about 0.7V, so 4.5VF is
approximately 3V), and if it is above this, the comparator
switches on, and charges the smoothing capacitor C7.
The operating point of the amplifier’s ch1 and ch2 output
stages is fixed at 3VF, so when the signal output voltage
is 1.5VF (an effective value of approximately 0.75V), the
comparator goes on, DC signals for electronic poten-
tiometer control are generated, and the ALC starts oper-
The electronic potentiometers are connected between
the input lines (pins 2 and 8) and GND, and the input sig-
nals is attenuated by the ratio of the electronic potentiom-
eter resistances and the external resistors R1 and R2. The
range of the ALC can be varied by the values of R1 and
R2, but if they are too large the S / N ratio will worsen. Suf-
ficient ALC range should be obtained with R1 and R2 val-
ues of around several kohms. C7 and R7 connected to pin
5 set the ALC attack and recovery times. The larger the
values of these constants, the longer the recovery time,
and the smaller the value of C7 the shorter the attack


BA3308 전자부품, 판매, 대치품
Audio ICs
FElectrical characteristics curves
BA3308 / BA3308F / BA3308FV


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Dual preamplifier with ALC

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