Audio Accessory ICs
Preamps with Built-in ALC
BA3308F,BA3308FV
No.11087ECT01
●Description
The BA3308F/FV is a dual preamplifier for recording and playback with ALC (auto level control), developed for stereo radio,
cassette recorders, tape recorders, and other pre amplifiers audio applications.
ALC circuit has a build in rectification circuit with wide adjustable dynamic range, high gain, low distortion amplifiers with
direct coupling and mute circuit, used to cut off pop noise during power on.
Available in SOP14, or SSOP-B14 Packages.
●Features
1) Built-in ALC rectification diode
2) Wide operating power supply voltage range (V
CC
=4.5~14 V)
3) Low current consumption (I
Q
=3.5mA)
4) High gain (G
VO
=80dB)
5) Low distortion (THD=0.1%)
6) Low noise (V
NIN
=1
μV
rms
)
7) Input coupling capacitor not needed
8) Good ALC channel balance
9) Built-in power supply mute circuit
10) Dynamic range of ALC can be changed by attaching input resistance.
●Applications
Stereo radio, cassette tape recorders, stereo cassette decks, home stereos, music centers, etc.
●Line
up matrix
Part No.
Package
BA3308F
SOP14
BA3308FV
SSOP-B14
www.rohm.com
© 2011 ROHM Co., Ltd. All rights reserved.
1/9
2012.06 - Rev.C
BA3308F,BA3308FV
●Absolute
maximum ratings(Ta=25℃)
Parameter
Supply voltage
BA3308F
Power
dissipation
BA3308FV
Operating temperature
Storage temperature
Symbol
V
CC
Pd
Topr
Tstg
Limits
16
450
350
*2
－25½＋75
－55½＋125
*1
Technical Note
Unit
V
mW
℃
℃
*
1
Reduce by 4.5 mW/C over 25C, when mounted on a 70mm×70mm×1.6mm PCB board.
2
* Reduce by 3.5 mW/C over 25C
●Operating
conditions(Ta=25℃)
Parameter
Supply voltage
Symbol
V
CC
Min.
4.5
Typ.
-
Max.
14
Unit
V
Note: This IC is not designed to be radiation-resistant.
●Electrical
characteristics(Unless
otherwise noted, Ta=25℃, Vcc=7.0V, f=1kHz, BPF20½20kHz)
Parameter
Quiescent current
Open loop voltage gain
Total harmonic distortion
Input resistance
Maximum output voltage
Input conversion noise
voltage
ALC range
ALC channel balance
Channel separation
Symbol
I
Q
G
VO
THD
R
IN
V
OM
V
NIN
ALC
ΔALC
CS
Min.
1.5
70
-
15
0.6
-
40
-
60
Typ.
3.5
80
0.1
25
1.2
1
45
0
75
Max.
4.5
-
0.3
45
-
2
-
2.5
-
Unit
mA
dB
%
kΩ
V
rms
μV
rms
dB
dB
dB
THD=1%
Rg=2.2kΩ, referenced to NAB 34dB
at 1kHz
R
g
=3.9 kΩ, V
IN
＝-70
dBV standard,
THD=3%
V
IN
=-60dBV,-30dBV
V
O
=0dBV, NAB 34dB
V
IN
=0V
rms
V
OUT
=-10dBV
NAB34dB, V
OUT
=40mV
rms
Conditions
Test
Circuit
Fig.17
Fig.17
Fig.17
Fig.17
Fig.17
Fig.17
Fig.17
Fig.17
Fig.17
www.rohm.com
© 2011 ROHM Co., Ltd. All rights reserved.
2/9
2012.06 - Rev.C
BA3308F,BA3308FV
●Block
diagram
Technical Note
BA3308F/FV
OUTPUT1
1
GND
N.C.
2
3
4
5
6
7
V
cc
ALC
14 N.C.
13
INPUT1
12 N.C.
11
NF1
ALC
V
CC
N.C.
10
NF2
9
8
INPUT2
N.C.
OUTPUT2
Fig.1
www.rohm.com
© 2011 ROHM Co., Ltd. All rights reserved.
3/9
2012.06 - Rev.C
BA3308F,BA3308FV
●Electrical
characteristic curves (Reference data)
Technical Note
Fig.2 Quiescent current vs.
power supply voltage
Fig.3
Quiescent current vs.
ambient temperature
Fig.4 Voltage gain vs. frequency
Fig.5 Total harmonic distortion vs.
frequency
Fig.6 Voltage gain vs.
supply voltage
Fig.7 Closed loop voltage gain vs.
ambient temperature
Fig.8 Input conversion noise voltage
vs. signal source resistance
Fig.9 Channel separation vs.
frequency
Fig.10 ALC characteristics
Fig.11 Input/output characteristics
Fig.12 Maximum output voltage vs.
power supply voltage
Fig.13 Maximum output voltage vs.
load resistance
www.rohm.com
© 2011 ROHM Co., Ltd. All rights reserved.
4/9
2012.06 - Rev.C
BA3308F,BA3308FV
●Description
of operations
1. Recording
1) Record amplifier
BA3308
Cont
Technical Note
ch2
(ch1)
The BA3308F/FV amplifier of ch1 and ch2 input stage
(13pin, 9pin) can be direct coupled or use coupling
capacitors (C1/C2). The voltage gain of the record amplifier
is determined by G
V
=R
5
/R
3
. The R5/R6, and C3/R3 regulate
control of the pop noise that occurs at power-on (see
“Cautions on use”) and direct current bias fed back is set by
R5/R6 and C5/C6 at the output stage.
ch1
(ch2)
ch2
(ch1)
2
13(9)
(8)
R
1
(R
2
)
3.9k
C
1
(C
2
)
10F
1
11(10)
(9)
R
5
(R
6
)
18k
R
3
(R
4
)
39
C
3
(C
4
)
100F
3 (7)
1
4
5
C
5
(C
6
)
10F
C
7
(C
8
)
22F
R
7
(R
8
)
1M
INPUT
OUTPUT
Fig.14
Fig.5
2) ALC
The BA3308F/FV has an on-chip signal rectifier and electronic
volume needed for ALC. The signal rectifier compares the direct
current output voltage that is superposed in the output stage (1, 7pin)
signal to the reference voltage 4.5V
F
(≒3V; 1V
F
is approximately
0.7V) in the comparator circuit and if the output voltage is higher, it
turns the comparator ON to charge the smoothing capacitor C
7
.
Since the operation point of the output stage of amplifier ch1 and ch2
is fixed at 3V
F
, the comparator turns ON when the peak value of the
signal output voltage is 1.5V
F
(effective value approx. 0.75V). Once
the direct current signal for electronic volume is controlled, ALC
operation starts. The electronic volume, which is connected between
the input line (13, 9pin) and GND, causes the input signal to
attenuate according to the ratio of the external resistance (R
1
, R
2
) to
the resistance value of the electronic volume. The ALC range varies
according to the values of R
1
and R
2
. For small ALC variation the
S/N will determinate an adequate ALC range is obtained by applying
several kΩ of the R
1
and R
2
. The attack time and recovery time of
ALC are set according to C7 and R7 of 4pin. If the time constants
(C
7
, R
7
) are large, the recovery time will be long and as C
7
becomes
smaller, and the attack time will be shorter.
ch1
(ch2)
ch2
(ch1)
ch2
(ch1)
Comp
Cont
4.5V
F
BA3308
V
OUT
(DCAC)
1 (7)
4
13(9)
3 (7)
3V
F
R
7
5
2 (8)
C
7
R
1
(R
2
)
Fig.15
Fig.6
www.rohm.com
© 2011 ROHM Co., Ltd. All rights reserved.
5/9
2012.06 - Rev.C
京公网安备 11010802033920号
EEWORLD
