LA4270.PDF

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LA4270
Ordering number:ENN1724D
Monolithic Linear IC
LA4270
6W Dual-Channel AF Power Amplifier
Features
• High-output dual-channel AF Power IC.
(P O =6.0W
´
2, V CC =25V, R L =8
W
Package Dimensions
unit:mm
3024A-SIP10H
W
, f=1kHz,
[LA4270]
P O =2W).
• Minimum number of external parts requierd (no boot-
strap capacitor requierd).
• Low pop noise at the time of power switch ON/OFF.
• High ripple rejection (58dB typ).
• Wide supply voltage range (10V to 32V).
• On-chip protector against abnormality (thermal shutdown,
overvoltage).
27.0
20.0
4.0
1
1.4
0.5
2.54
10
2.07
0.4
2.0
Specifications
Absolute Maximum Ratings at Ta = 25˚C
SANYO : SIP10H
P
S
C
R
U
M
s
v
V C
m
3
V
M
o
c
I O
p
3
V
A
p
d
P
m
W
h
s
S
P
g
2
W
O
t
T
–
t
+
˚C
˚C
S
t
T
–
t
+
Operating Conditions at Ta = 25˚C
P
S
C
R
U
R
s
v
V C
2
V
O
v
r
V C o
1
t
3
V
R
l
r
R L
8
W
Operating Characteristics at Ta = 25˚C, V CC =25V, R L =8
W
, f=1kHz, Rg=600
W
, See specified test circuit
P
S
C
R
U
m
t
m
Q
c
I
C
2
4
9
m
V
g
V
3
4
4
d
O
p
P O
T
5
6
W
T
h
d
T
P O
=
0
0
%
O
n
v
V
N
R
W
,
B
t
2
0
1
m
R
r
S
R
W , R
=
V
R
=
4
5 d
Continued on next page
Any and all SANYO products described or contained herein do not have specifications that can handle
applications that require extremely high levels of reliability, such as life-support systems, aircraft’s
control systems, or other applications whose failure can be reasonably expected to result in serious
physical and/or material damage. Consult with your SANYO representative nearest you before using
any SANYO products described or contained herein in such applications.
SANYO assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges,or other
parameters) listed in products specifications of any and all SANYO products described or contained
herein.
SANYO Electric Co.,Ltd. Semiconductor Company
TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110-8534 JAPAN
21500TH (KT)/40194HK/3210MO/8026KI/6126AT/6245KI, TS No.1724–1/9
, f=1kHz, THD=1.0%)
• Low distortion (THD=0.1%, V CC =25V, R L =8
11028120.003.png 11028120.004.png
LA4270
Continued from preceding page.
P
S
C
R
U
m
t
m
C
C
R
W
4
6
d
C
b
D
V
1
d
Equivalent Circuit Block Diagram and Pin Assignment
Sample Printed Circuit Pattern
No.1724–2/9
11028120.005.png
LA4270
Sample Application Circuit 1 : Dual-channel use (specified Test Circuit)
Description of External Parts
C1, C4 :
Input capacitors
(4.7
m
F)
Since the DC potential of the input pins is not 0, the two capacitors cannot be omitted. Decreasing the
capacitor value extremely causes the frequency response to lower at low frequencies.
C2, C3 :
Feedback capacitors
(100
m
F)
Decreasing the capacitor value causes the frequency response to lower at low frequencies. Increasing
the capacitor value makes the starting time later.
C5 :
Ripple filter capacitor
(100
m
F/25V)
Decreasing the capacitor value provides less ripple rejection. Decreasing the capacitor value also
makes the starting time earlier.
C6, C9 :
Output capacitors
(1000
m
F/25V)
Decreasing the capacitor value provides less power at low frequencies.
C7, C8 :
Oscillation blocking capacitors
F polyester Decreasing the capacitor value causes oscillation to be liable to occur. It is recommended to use
film capacitors)
m
polyester film capacitors which are excellent in high frequency response, temperature characteristic.
The use of electrolytic capacitors or ceramic capacitors may cause oscillation to occur at low tem-
peratures.
C10 :
Power capacitor
(470
m
F/35V)
Decreasing the capacitor value causes ripple to be liable to occur. If the distance between the IC and
this capacitor is made long or this capacitor is removed, oscillation may occur.
R1, R2 :
Resistors connected in series with oscillation blocking capacitors
(2.2
W
)
Used to prevent phase shift attributable to the oscillation blocking capacitors so that oscillation is
hard to occur. Increasing or decreasing the resistor value causes oscillation to be liable to occur. The
optimum value must be used.
No.1724–3/9
(0.1
11028120.006.png
LA4270
External Muting
1. Lowering of potential at ripple filter pin (pin 3).
Muting can be provided by discharging resistor R
connected across pin 3 and GND to lower the po-
tential at pin 3. Too small an R value causes pop
noise to occur ; and too large an R value causes
muting to fail to work.
If no adequate R value is obtained, it is recom-
mended that the R value is made rather small and
the C5 value is increased.
2. Application of positive bias to NF pins.
Muting can be provided by positive bias applied to
the NF pins. In this case, the R value must be de-
termined so that the potential at the NF pins (pins
1, 6) does not exceed 3V at the muting mode.
. It is impossible
to use the IC at a voltage gain greater than this. In
an application where the IC is used at a voltage
gain of less than 40dB, resistors are connected in
series with feedback resistors as shown right. In
this application, however, oscillation is liable to
occur. So, the voltage gain must not be less than
30dB.
and 300
W
Sample Application Circuit 2 : Bridge amplifier use
No.1724–4/9
Voltage Gain
The voltage gain is fixed to 40dB by the ratio of
on-chip resistors 30k
W
11028120.001.png
LA4270
, more distortion results,
making it impossible for the IC to deliver power at THD=1% as in 2-channel use. It is possible for the IC to deliver
power at THD=5% or 10%
W
No.1724–5/9
In this application, output capacitors must be used. Since the IC handles an apparent load of 4
11028120.002.png

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