BA3308F-E1 [ROHM]
2 CHANNEL, AUDIO PREAMPLIFIER, PDSO14, SOP-14;
| 型号： | BA3308F-E1 |
| 厂家： | 
ROHM |
| 描述： | 2 CHANNEL, AUDIO PREAMPLIFIER, PDSO14, SOP-14 放大器 光电二极管 |
| 文件： | 总10页 (文件大小：194K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
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.
Thepreamplifiershavehighgainandlowdistortion, andcanbedirectlycoupledtothetapeheadwithoutcouplingcapaci-
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.
FApplications
Stereo radio cassette recorders, cassette decks and
home stereo systems and music centers
FFeatures
1) Built-in ALC rectifier diode.
2) Wide operating power supply voltage range (VCC =
4.5V to 14V).
6) Low noise (VNIN = 1µVrms)
7) Input coupling capacitors and not necessary.
8) Good ALC channel balance.
3) Low current dissipation (IQ = 3.5mV).
4) High gain (GVO = 80dB).
9) Power-on mute circuit.
10) ALC dynamic range can be varied by the addition
of an external input resistor.
5) Low distortion (THD = 0.1%).
FAbsolute maximum ratings (Ta = 25_C)
FRecommended operating conditions (Ta = 25_C)
193
Audio ICs
BA3308 / BA3308F / BA3308FV
FBlock diagram
FElectrical characteristics (unless otherwise noted, Ta = 25_C, VCC = 7.0V, f = 1kHz and BPF: 20Hz to 20kHz)
194
Audio ICs
BA3308 / BA3308F / BA3308FV
FMeasurement circuit
FApplication example
FApplication example circuit PCB (copper side)
195
Audio ICs
BA3308 / BA3308F / BA3308FV
FTotal application circuit
FCircuit operation
(1) Recording
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-
ating.
(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 electronic potentiometers are connected between
the input lines (pins 2 and 8) and GND, and the input sig-
nalsisattenuatedbytheratiooftheelectronicpotentiom-
eterresistancesandtheexternalresistorsR1 andR2. 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
time.
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
196
Audio ICs
BA3308 / BA3308F / BA3308FV
(2) Playback (See Fig. 7)
generation of a “pop” noise when power is applied). The
output stage (pins 3 and 7) operating point is fixed at 3VF.
Therefore, as indicated in the VMax. vs, VCC characteristic
(see Fig. 19), even if the VCC voltage is made larger than
5V, the maximum output voltage will not exceed 1.2V
(typ.). The ALC circuit is not required for playback, so pin
5 is grounded. The S/N ratio during playback is better if
the external resistors R1 and R2 that are connected to the
input pins (2 and 8) for recording are switched out.
During playback, the ch1 and ch2 amplifiers are used as
NAB equalizer amplifiers, and time constant circuits are
connectedbetweenpins1and3, and7and9inthenega-
tive-feedback section to give the NAB characteristics.
The voltage gain is given by:
GV = R11 ) R9 / (I ) jϖC9 S R9)
/R3
In the same way as for recording, the NAB time constant
circuit is adjusted to give the required gain (to prevent
197
Audio ICs
BA3308 / BA3308F / BA3308FV
FOperation notes
The BA3308 has a built-in power-on mute circuit to pre-
vent generation of a “pop” sound when the power is ap-
plied. The generation of the “pop” sound is prevented by
the DC blocking capacitors C3 and C4 connected to pins
1 and 9, and the charge time required for the ripple filter
capacitor C8 that is connected to pin 6.
To ensure correct operation of this circuit, use the values
given in the application example circuit for C3, C4, R3, R4,
C8 and R8.
FApplication board component layout (component side)
198
Audio ICs
BA3308 / BA3308F / BA3308FV
FElectrical characteristics curves
199
Audio ICs
BA3308 / BA3308F / BA3308FV
FExternal dimensions (Units: mm)
200
Product Designation
Page 1 of 2
ROHM-logo
Product Designation
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When ordering, specify the part number.
Check each code against the tables shown below.
Fill in from the left, leaving any extra boxes empty on the
right.
Product Designation
Ordering information
Packing and forming information only required for SOP, and QFP
parts that are required in tape and reel containers. For example,
to order part BA4558F on paper tape type E2, order number is
BA4558F-E2, when required in tube container, order number is
BA4558F.
Quick reference of packaging specifications
Container
type
Packaging
specification code
Package
Tube
container
DIP/SDIP
Tube
container
SIP/HSIP/ZIP/SZIP/RSIP-A3
Tube
container
SOP/SSOP/HSOP/WSOP-10/WSOP-
L10
Embossed
tape
E1, E2
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Product Designation
Page 2 of 2
Embossed
tape
SSOP-A54
E2
Tray
Tray (dry
VP
QFP/SQFP/VQFP/UQFP/TQFP/PBGA pack)
Embossed
tape
E1, E2
Bulk
TO220FP
Tube
container
Embossed
tape
SMP5
TL, TR
E1, E2
Embossed
tape
TO252
RSLP8
Embossed E2(Sprocket 1pin,
tape
Horizontal)
E2(Sprocket 1pin,
Embossed Horizontal), E4
RSIP13
tape
(Sprocket 1pin,
Vertical)
Note: SOP type can be delivered in tube, paper tape, or embossed tape.
BGA/CSP package | SIP/ZIP package
QFP package | Photo package
SOP package | Product Designation
DIP package | Packaging Specification
[LSI Package Assemblies]
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