BA3304F PDF 데이터시트 : 부품 기능 및 핀배열

부품번호 BA3304F
기능 3V Dual Preamplifier
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BA3304F 데이터시트, 핀배열, 회로
Audio ICs
3V dual preamplifier
The BA3304F is a monolithic, dual-preamplifier IC designed for 3V applications. It has been designed especially for low-
voltage operation.
The preamplifiers can be directly coupled to the head to minimize the “pop” noise at power on. When combined with the
Rohm BA5204, it is a simple matter to design a high-performance circuit for cassette players.
3V headphone stereos, 3V micro-cassette players and
low-voltage stereo equipment
1) Low noise (VNIN = 1.2µVrms).
2) Input coupling capacitors not required.
3) No input coupling capacitors means high bass stabil-
4) Good channel balance.
5) Built-in bias circuit minimizes “pop” noise.
6) Emitter-follower output for low output impedance.
7) Good low voltage characteristics (operation possible
from Typ. 1.2V).
FBlock diagram

BA3304F pdf, 반도체, 판매, 대치품
Audio ICs
FOperation notes
(1) Input-side virtual ground
If coupling capacitors are used to connect the head with
the preamplifier input, the capacitor charging current
flows in the head and can magnetize it. To prevent this,
a virtual ground is used on the input side, and coupling
capacitors are not required even with a single-rail supply.
This is the bias pin input and the virtual ground point for
the negative feedback, and the bias for the input transis-
tor is taken from this terminal. The only DC current that
flows in the magnetic head is the base bias current for the
input transistor, which is not enough to magnetize the
(2) Capacitor for prevention of oscillation and RF mix-
With the BA3404F, a capacitor must be connected be-
tween each input pin and the bias pins to prevent oscilla-
tion and RF mixing. The recommended value for this ca-
pacitor is 100pF. If it is too small, oscillation and RF noise
can adversely affect circuit performance. Conversely, if
the value of the capacitor is too large, it will affect the au-
dio frequency characteristics. These capacitors can also
be used for treble compensation. Determine the value
based on the relationship with the magnetic head imped-
(3) Bypass capacitor
The capacitor connected in series with the gain-setting
resistor between the NF pin and the bias pin, is the by-
pass capacitor. The value of this capacitor determines
the bass characteristics
(4) Playback equalizer(NBA)
The playback equalizer characteristics are determined
by the RC circuit connected between the output pin and
the NF pin. For the circuit shown in Fig. 4, with a closed-
loop gain of GVC (dB) at a frequency of 1kHz, the value
of the circuit components is given by the following equa-
R2 = 15.6 R3 10Gvc / 20
R1 =
3180 10*6
The recommended value for R3 is about 100. If R3 is too
large, the voltage gain will not match the calculated val-
(5) Capacitive loads
The BA3304F has an emitter-follower output, so oscilla-
tion is apt to occur if the load is capacitive (if the capaci-
tance of the load exceeds 150pF with VCC = 3V, oscillation
will occur). Oscillation is apt to occur if the closed-loop
gain (GVC) is lower than 30dB at f = 1kHz. Caution is espe-
cially required with long lengths of thin shielded wire. If
use of a large capacitive load cannot be avoided, connect
a resistor of a few hundred ohms in series with the load.
(6) Input / output interference
Performance degradation due to input / output interfer-
ence is related to the amplifier gain, the amount of feed-
back from the output to the input, and amplifier phase
rotation. Care is required to avoid component layouts
that will cause input / output interference when high gain
is used. With regard to component layout, we recom-
mend that you separate the virtual earth for the input and
output components, and have one earth at the bias pin.
(7) Assembly precautions
(a) Power supply
To avoid possible destruction of the IC, before connect-
ing the power supply pins to the PCB, ensure that there
are no shorts due to solder bridges, and take care to en-
sure that the polarity is correct.
(b) Static
Static electricity that accumulates on the clothing of oper-
ators and on belt conveyors can range from thousands
to tens of thousands of volts. To prevent damage to com-
ponents due to static discharge, ensure that all operators
and conveyor belts are earthed.


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3V Dual Preamplifier

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