Datasheet
Ground Isolation Amplifier
BA3121F
General Description
BA3121F is a ground isolation amplifier developed for
car audio applications. This IC efficiently eliminates
problems caused by wiring resistance and removes
noise generated by other electrical devices used in
automobiles. The external capacitor values required for
this IC are so small that it allows for compact and
reliable set design.
Key Specifications
Power Supply Voltage Range:
4V to 18V
Quiescent Current:
9.0mA (Typ)
High Common-mode Rejection Ratio(1kHz):
57dB (Typ)
Low Noise:
V
NO
= 3.5µVrms(Typ)
Low Distortion:
THD = 0.002% (Typ)
Operation temperature range:
-30°C to +85°C
Features
Large Capacitors not Required
High Common-mode Rejection Ratio
Low Noise
Low Distortion
Two Channels
Package
W(Typ) x D(Typ) x H(Max)
Applications
Car audio systems
SOP8
5.00mm x 6.20mm x 1.71mm
Typical Application Circuit
○Product
structure：Silicon monolithic integrated circuit
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© 2015 ROHM Co., Ltd. All rights reserved.
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○This
product has no designed protection against radioactive rays
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BA3121F
Block Diagram and Pin Configuration
TOP VIEW
VM1
VM2
Absolute Maximum Ratings
(Ta = 25C)
Parameter
Power Supply Voltage
Power Dissipation
Operation Temperature
Storage Temperature
Symbol
V
CC
Pd
Topr
Tstg
Limit
18
0.45
(Note 1)
-30 to +85
-55 to +125
Unit
V
W
°C
°C
(Note 1) Reduced by 4.5mW in Ta of 1°C over 25°C .
Caution:
Operating the IC over the absolute maximum ratings may damage the IC. The damage can either be a short circuit between pins or an open circuit
between pins and the internal circuitry. Therefore, it is important to consider circuit protection measures, such as adding a fuse, in case the IC is operated over
the absolute maximum ratings.
Recommended Operating Conditions
(Ta = 25C)
Parameter
Power Supply Voltage
Symbol
V
CC
Min
4
Typ
12
Max
18
Unit
V
Electrical Characteristics
(Unless otherwise noted, Ta = 25C, V
CC
= 12V, f = 1kHz, Rg = 1.8kΩ)
Parameter
Quiescent Current
Output Noise Voltage
Voltage Gain
Maximum Output Voltage
Total Harmonic Distortion
Common-mode Rejection Ratio
Common-made Voltage
Ripple Rejection Ratio
Channel Separation
Slew Rate
Input Resistance
Symbol
I
Q
V
NO
G
V
V
OM
THD
CMRR
V
CM
RR
CS
SR
R
IN
Min
5.6
－
-1.5
1.8
－
41
2.5
72
-
-
44
Typ
9.0
3.5
-0.04
2.0
0.002
57
3.75
80
82
2.0
55
Max
14.0
8.0
+1.5
－
0.02
-
-
-
-
-
66
Unit
mA
μVrms
dB
Vrms
％
dB
Vrms
dB
dB
V/μS
kΩ
V
CC
＝8V,CMRR＝40dB
f
RR
＝100Hz,V
RR
＝-10dBm,
Rg＝0Ω
V
IN
＝-10dBm,
Rg＝1.8kΩ/OPEN
Conditions
V
IN
＝0Vrms
BPF＝20Hz-20kHz
V
OUT
＝-10dBm,
Rg＝0Ω
THD＝0.1％, V
CC
＝8V
V
OUT
＝0.7Vrms
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BA3121F
Typical Performance Curves
Power Supply Voltage : V
CC
(V)
Figure 1. Quiescent Current vs
Power Supply Voltage
Maximum Output Voltage : V
OM
(Vrms)
V
IN
= 0Vrms
Quiescent Current : I
Q
(mA)
THD=0.1%
R
L
= 10kΩ
f=1kHz
Power Supply Voltage : V
CC
(V)
Figure 2. Maximum Output Voltage vs
Power Supply Voltage
Output Noise Voltage : V
NO
(µVrms)
Power Supply Voltage : V
CC
(V)
Figure 3. Output Noise Voltage vs Power Supply
Voltage
Voltage Gain : G
V
(dB)
Power Supply Voltage : V
CC
(V)
Figure 4. Voltage Gain vs Power Supply Voltage
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TSZ22111・15・001
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BA3121F
Typical Performance Curves – continued
V
CC
= 12V
V
IN
=-10dBm
Channel Separation : CS (dB)
Voltage Gain : G
V
(dB)
V
CC
=12V
V
IN
= -10dBm
Rg=1.8kΩ/Open
R
L
=10kΩ
10 20
50 100 200 500 1k 2k
5k 10k 20k
10 20
50 100 200 500 1k 2k
5k 10k 20k
Frequency : f (Hz)
Figure 5. Voltage Gain vs Frequency
Frequency : f (Hz)
Figure 6. Channel Separation vs Frequency
V
CC
= 12V
V
RR
=-10dBm
Rg=0Ω
R
L
=10kΩ
10 20
50 100 200 500 1k 2k
5k 10k 20k
Total Harmonic Distortion : THD (%)
Ripple Rejection Ratio : RR (dB)
V
CC
= 12V
f=1kHz
R
L
=10kΩ
Frequency : f (Hz)
Figure 7. Ripple Rejection Ratio vs Frequency
Output Voltage : V
OUT
(Vrms)
Figure 8. Total Harmonic Distortion vs Output
Voltage
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TSZ22111・15・001
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BA3121F
Typical Performance Curves – continued
Total Harmonic Distortion : THD (%)
V
CC
= 12V
V
OUT
= 0.7Vrms
R
L
= 10kΩ
Common Mode Rejection Ratio : CMRR (dB)
V
CC
= 12V
V
N
=-20dBm
Rg=1.8kΩ
(VM1, VM2)=(100µF, 47µF)
(VM1, VM2)=(47µF, 22µF)
(VM1, VM2)=(22µF, 10µF)
10 20
50 100 200 500 1k 2k 5k 10k 20k
10 20 50 100 200 500 1k 2k
5k 10k 20k
Frequency : f (Hz)
Figure 9. Total Harmonic Distortion vs Frequency
Frequency : f (Hz)
Figure 10. Common Mode Rejection Ratio vs Frequency
Common Mode Rejection Ratio : CMRR (dB)
V
CC
= 8V
f=1kHz
Rg=1.8kΩ
Input Noise Voltage : V
CM
(Vrms)
Figure 11. Common Mode Rejection Ratio vs Input Noise
Voltage
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© 2015 ROHM Co., Ltd. All rights reserved.
TSZ22111・15・001
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TSZ02201-0C2C0EZ00390-1-2
13.Nov.2015 Rev.001
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