20W 2-Channel Class-AB BTL Power Amplifier for Car Stereo

Ordering number : ENA1783A
LA4708N
Monolithic Linear IC
20W 2-channel BTL AF Power
Amplifier for Car Stereo
http://onsemi.com
Overview
The LA4708N is a BTL two-channel power IC for car audio developed in pursuit of excellent sound quality. Low-region
frequency characteristics have been improved through the use of a new NF capacitor-less circuit, and crosstalk which
causes “muddy” sound has been reduced by improving both circuit and pattern layout. As a result, the LA4708N provides
powerful bass and clear treble. In addition, the LA4708N features on-chip protectors and standby switch.
Features
 High power : supports total output of 30W  30W (VCC = 13.2V, THD = 30%, RL = 4)
 Supports RL = 2 (PO = 30W when VCC = 13.2V, THD = 10%)
 Designed for excellent sound quality (fL  10Hz, fH = 130kHz)
 NF capacitor-less
 Any on time settable by external capacitor
 Less pop noise
 Standby switch circuit on chip (microprocessor supported)
 Various protectors on chip (output-to-ground short/output-to-VCC short/load short/overvoltage/thermal shutdown circuit)
Specifications
Maximum Ratings at Ta = 25C
Parameter
Symbol
Conditions
Ratings
Unit
Maximum supply voltage
VCC max 1
No signal, t = 60s
Surge supply voltage
VCC surge
t 0.2s, single giant pulse
50
V
Maximum output current
IO peak
Per channel
4.5
A
Allowable power dissipation
Pd max
Arbitrarily large heat sink
Operating temperature
Topr
35 to 85
C
Storage temperature
Tstg
40 to 150
C
VCC max 2
24
V
16
V
37.5
W
* Set VCC, RL in a range that does not exceed Pd max = 37.5W
Stresses exceeding those listed in the Maximum Ratings table may damage the device. If any of these limits are exceeded, device functionality should not be assumed,
damage may occur and reliability may be affected.
SIP18H
ORDERING INFORMATION
See detailed ordering and shipping information on page 9 of this data sheet.
Semiconductor Components Industries, LLC, 2014
March, 2014
30314HK/61610SY 20100405-S0010 No.A1783-1/9
LA4708N
Operating Conditions at Ta = 25C
Parameter
Symbol
Recommended supply voltage
VCC
Operating voltage range
VCC op
Recommended load resistance
RL
Recommended load resistance range
RL op
Conditions
Ratings
Unit
13.2
Range where Pd max is not exceeded
V
9 to 16
V
4

2 to 4

Functional operation above the stresses listed in the Recommended Operating Ranges is not implied. Extended exposure to stresses beyond the Recommended
Operating Ranges limits may affect device reliability.
Electrical Characteristics at Ta = 25C, VCC = 13.2V, RL = 4, f = 1kHz, Rg = 600
Parameter
Symbol
Conditions
min
typ
Unit
ICCO
Standby current
lst
Voltage gain
VG
Total harmonic distortion
THD
PO = 2W
Output power
PO1
THD = 10%
PO2
THD = 10%, VCC = 14.4V
24
W
PO3
THD = 10%, RL = 2
30
W
VN offset
Rg = 0
Output offset voltage
70
max
Quiescent current
38
Output noise voltage
VNO
Rg = 0, B.P.F. = 20Hz to 20kHz
Ripple rejection ratio
SVRR
Rg = 0, fR = 100Hz, VR = 0dBm
Channel separation
CHsep
Rg = 10k, VO = 0dBm
Input resistance
ri
Standby pin applied voltaga
Vst
Amp on, applied through 10k
16
150
250
mA
10
60
A
40
42
dB
0.07
0.4
20
300
300
0.1
40
0.5
50
50
60
21
30
2.5
%
W
mV
mVrms
dB
dB
39
VCC
k
V
Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product performance may not be
indicated by the Electrical Characteristics if operated under different conditions.
Package Dimensions
unit : mm
SIP18 36.8x13.8 / SIP18H
CASE 127AS
ISSUE A
GENERIC
MARKING DIAGRAM*
XXXXXXXXXX
YMDDD
XXXXX = Specific Device Code
Y = Year
M = Month
DDD = Additional Traceability Data
*This information is generic. Please refer to
device data sheet for actual part marking.
No. A1783-2/9
LA4708N
Pd max -- Ta
35
θf = 1.5°C/W
30
θjc = 2.0°C/W
2.0°C/W
25
3.2°C/W
20
4.1°C/W
15
7.0°C/W
10
No Fin
5
3.5
0
-20
0
20
40
60
80
θf -- Sf
3
Arbitrarily large heat sink
Heat sink thermal resistance, θf -- °C/ W
Allowable power dissipation, Pd max -- W
40
100
120
Ambient temperature, Ta -- °C
140
AI heat sink, t = 1.5mm
Tightening torque 39N cm
With silicone grease applied
2
10
7
5
3
2
2
160
3
5
7
2
100
3
5
Heat sink area, Sf -- cm2
JK470801
7 1000
JK470802
Block Diagram
100μF/ 16V
VCC
+
C2
VCC1
18
1
3
OUTPUT PIN-TO-VCC
SHORT PROTECTOR
RIPPLE
FILTER
POWER
PREDRIVER
C1
IN1
+
17
+
IN
-
2
2.2μF/ 6.3V
C5
POWER 16
GND1
LOAD SHORT
PROTECTOR
PREDRIVER
POWER
+
2200μF
INVERTING
OUT1
0.1μF
∗∗
C6
R2 2.2Ω
R3
2.2Ω
∗∗
0.1μF
C7
+
RL
2 to 4Ω
15
NONINVERTING
OUT1
PRE GND
OFF ON
4
R1
10kΩ
5
BIAS
CIRCUIT
OVERVOLTAGE/
SURGE PROTECTOR
VCC
OUTPUT PIN-TO-GND
SHORT PROTECTOR
THERMAL
SHUTDOWN
STANDBY
SW
OUTPUT PIN-TO-GND
SHORT PROTECTOR
∗∗
POLYESTER FILM
CAPACITOR
+5V
C4
IN2
+
POWER
PREDRIVER
14
NONINVERTING
OUT2
0.1μF
C8
2.2Ω
∗∗
+
IN
-
7
2.2μF/ 6.3V
LOAD SHORT
PROTECTOR
POWER
13
GND2
R4
2.2Ω
0.1μF
C9
R5
∗∗
PREDRIVER
POWER
12
POP NOISE
PREVENTION
CIRCUIT
6
33μF/ 6.3V +
OUTPUT PIN-TO-VCC
SHORT PROTECTOR
8
9
10
11
N.C
C3
+
-
RL
2 to 4Ω
INVERTING
OUT2
VCC2
Pins 1,9 : Don't use.
Pin 10 : No connection.
Each Pin Voltage
VCC = 13.2V, 5V applied through STBY = 10k, RL = 4, Rg = 0
Pin No.
1
Name
Pin voltage (V)
0.29
2
3
4
5
6
IN1
DC
Pre-GND
STBY
ON TIME
1.58
6.55
0
3.2
2.28
Pin No.
7
8
9
10
11
12
Name
IN2
POP
-
N.C
VCC2
OUT 2
Pin voltage (V)
1.58
2.08
0.29
0
13.2
6.5
Pin No.
13
14
15
16
17
18
Name
PWR-GND 2
OUT 2
OUT 1
PWR-GND 1
OUT 1
VCC1
Pin voltage (V)
0
6.5
6.5
0
6.5
13.2
No. A1783-3/9
LA4708N
Sample Print Pattern
VCC
1
+
C5
+
C1 IN1
+
C6 OUT1
PRE GND
C2
R1
R2
GND
STB
+
C7
C3
IN2
C
+ 4
R3
OUT2
C8
R4
GND
Copper foil area 90 × 105mm2
R5
C9
Description of External Components
C1, C4
Input capacitors
C2
Decoupling capacitor
(ripple filter)
C3
Amplifier on time setting
capacitor
C5
Power supply capacitor
C6, C7, C8, C9
Oscillation blocking capacitors
Use polyester film capacitors (Mylar capacitors) with good temperature characteristics. (R2, R3,
R4, and R5 used jointly.) Since stability may be affected slightly by the pattern layout, etc.,
0.1F or more is recommended.
R1
Standby switch current
limiting resistor
10k is recommended (when the applied voltage for the standby switch is 2.5V to 13.2V). This
resistor cannot be removed.
2.2F is recommended. fL can be varied by C1, C4 capacitances to adjust the bass range.
Approximately 0.8 second for 33F. Since the on time is proportional to this capacitance, it can
be set as desired by varying this capacitance. (Refer to the characteristics curve.)
No. A1783-4/9
LA4708N
Features of IC Inside and Usage Notes
Standby function
 Pin 5 is the standby switch pin. The amplifier is
turned on by applying approximately 2.5V or more
to this pin through an external resistor (R1).
 If voltage in excess of 13.2V is to be applied to the
standby switch, calculate the value of R1 using the
following formula so that the current flowing into
pin 5 is 500A or less:
R1 =
Applied voltage 1.4V
500A
10k
Mute function
 Pin 6 is the connector for the capacitor that determines the on time in order to prevent pop noise. By grounding this
pin, the amplifier can implement mute operation. In this case, the recovery time depends on C3.
How to reduce pop noise
 Although the LA4708N reduces pop noise, an electrolytic capacitor of between 0.47 and 2.2F can be connected
between pin 8 and the pre-GND to further reduce pop noise that occurs when power supply is turned on/off
(standby switch on/off). The larger the capacitance, the lower the frequency of pop noise, and it is barely audible,
but sound residue of the sound signal is liable to linger when power is turned off. Pin 8 is the bias pin for the output
amplifier and normally is left open.
Protectors
 In an output-to-ground and output-to-VCC short protector system configuration, if a DC resistor is connected
between amplifier output pin and GND, the protector may operate, causing the amplifier not to start operating.
Therefore, as a general rule, no DC resistor should be connected between amplifier output pin and GND.
 In order to prevent damage or degradation which may be caused by abnormally heated IC, the LA4708N has a thermal
shutdown protector. Accordingly, if the IC junction temperature (Tj) climbs to around 170 to 180C due to inadequate
heat dissipation, the thermal shutdown protector will operate to control the output gradually into attenuation.
 Also be fully careful of handling other protectors built in the LA4708N.
Miscellaneous
 Since pins 1 and 9, which are unused, are connected internally, they must be left open.
 Pin 10 is an NC pin (no internal connection).
No. A1783-5/9
LA4708N
ICCO -- VCC
5
RL = Open
Rg = 0
VST = 5V
180
160
3
2
Output power, PO -- W
140
120
100
80
60
0
0
4
8
12
16
20
Supply voltage, VCC -- V
24
VCC
2V
= 13.
2
1.0
7
5
28
dm
ax
60
din
Output power, PO -- W
gP
50
ee
36
32
28
24
=
RL
20
2Ω
Ω
RL
16
7
=4
2
10
3
5
7 100
2
Input level, VIN -- mVrms
PO -- VCC
f = 1kHz
Rg = 600Ω
THD = 10%
Dual channel drive
5
JK470806
Ex
c
Output power, PO -- W
40
V CC
3
0.1
7
5
3
20
44
V
4.4
=1
3
2
40
48
10
7
5
PO -- VIN
RL = 4Ω
f = 1kHz
Rg = 600Ω
VG = 40dB
Dual channel drive
12
3
5
JK470807
PO -- VCC
f = 1kHz
Rg = 600Ω
THD = 30%
Dual channel drive
40
R
L=
2Ω
Quiescent current, ICCO -- mA
200
30
4Ω
=
RL
20
10
8
4
6
8
10
12
14
16
Supply voltage, VCC -- V
3
2
10
7
5
3
1.0
7
5
f = 10kH
z
100Hz
0.1
7
5
2
3
5
7 1.0
2
3
5
7 10
Output power, PO -- W
2
2
3
14
16
18
2
10
7
5
THD -- PO
3
2
1.0
7
5
f = 10k
Hz
3
2
100H
z
1kH
z
2 3
5 7 1.0
THD -- f
4
2
2
3
5
7 10
Output power, PO -- W
JK470810
VCC = 13.2V
RL = 4Ω
Rg = 600Ω
PO = 2W
20
JK470809
VCC = 13.2V
RL = 2Ω
Rg = 600Ω
Dual channel drive
7
5
0.1
5
2
3
5
7
JK470811
f Response
VCC = 13.2V
RL = 4Ω
Rg = 600Ω
VO = 0dBm at f = 1kHz
0
1.0
Response -- dB
Total harmoinc distortion, THD -- %
3
12
0.1
1kHz
3
0.1
10
Supply voltage, VCC -- V
THD -- PO
VCC = 13.2V
RL = 4Ω
Rg = 600Ω
Dual channel drive
3
2
8
JK470808
3
2
5
0
6
20
Total harmoinc distortion, THD -- %
Total harmoinc distortion, THD -- %
5
18
7
5
3
2
-2
-4
-6
0.1
7
-8
5
3
10
2 3
5 7 100
2 3
5 7 1k
2 3
5 7 10k
Input frequency, f -- Hz
2 3
5 7100k
JK470812
-10
10
2 3
5 7 100
2 3
5 7 1k
2 3
5 7 10k
Input frequency, f -- Hz
2 3
5 7100k
JK470813
No. A1783-6/9
LA4708N
Channel separation, CHSep -- dB
THD = 10%
20
18
3%
1%
VCC = 13.2V
RL = 4Ω
Rg = 600Ω
VG = 40dB
Dual channel drive
14
12
10
10
2 3
5 7 100
2 3
5 7 1k
2 3
5 710k
2 3
Input frequency, f -- Hz
3
2
0.1
7
5
3
5 7 1k
2
5
7 10k
2
3
5
7 100k
-60
1
CH2 CH
-80
0
-40
T2
1
OUT
-60
-80
The value of power supply capacitor is 0.47μF (Mylar)
2 3
5 7 1k
2 3
5 7 10k
2 3
Ripple frequency, fR -- Hz
2
100
7
C
5
I CC
3
2
=
7
5
(V C
3
2
)
C
10
Pd
6V
=1
Pd (
V
CC =
(V C
1.0
13.2
V)
7
7
5 7 100k
JK470815
OUT1
OUT2
-60
-80
2200μF (power supply capacitor)
is changed to 0.47μF (Mylar)
6
8
10
12
14
16
18
VCC = 13.2V
RL = 4Ω
fR = 100Hz/3kHz
-40
OUT2
fR = 100Hz
OUT1
-60
OUT1
OUT2
fR = 3kHz
-80
100
7
20
JK470817
SVRR -- VCCR
-20
2
10
)
2 3
The value of power supply capacitor is 0.47μF (Mylar)
VO
Calculate as SVRR = 20 log
VCCR
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
Power supply ripple voltage, VCCR -- Vrms
2
V
16
5 7 10k
-40
-100
0
5 7100k
Pd, ICC -- PO
2 3
-20
JK470818
RL = 4Ω
Rg = 600Ω
f = 1kHz
Dual channel drive
5 7 1k
RL = 4Ω
Rg = 0
fR = 100Hz
VCCR = 0dBm
0
OU
5 7 100
2 3
Supply voltage, VCC -- V
-20
2 3
5 7 100
SVRR -- VCC
-100
4
2
VCC = 13.2V
RL = 4Ω
Rg = 0
VCCR = 0dBm
-100
10
2 3
JK470816
SVRR -- fR
20
Ripple rejection ratio, SVRR -- dB
3
Input resistance, Rg -- Ω
CH2
CH1
3
2
2
Power dissipation, Pd -- W
-40
0
VCC = 13.2V
RL = 4Ω
DIN AUDIO
Ripple rejection ratio, SVRR -- dB
5
-20
Input frequency, f -- Hz
Ripple rejection ratio, SVRR -- dB
Output noise voltage, VNO -- mVrms
7
0
-100
10
5 7
VNO -- Rg
1.0
VCC = 13.2V
RL = 4Ω
Rg = 10kΩ
VO = 0dBm
JK470814
Current drain, ICC -- A
Power dissipation, Pd -- W
Output power, PO -- W
22
16
CH Sep -- f
20
2.0
2.2
JK470819
Pd, ICC -- PO
2
RL = 2Ω
Rg = 600Ω
f = 1kHz
Dual channel drive
)
6V
Allowable power dissipation package
5
=1
I CC CC
(V
10
7
5
Pd max = 37.5W
3
3
)
6V
2
Pd
10
(V
CC
Pd (VCC = 13.2V)
=1
2
1.0
7
7
5
5
5
5
3
3
3
3
2
7
2
2
7 0.1
2
3
5 7 1.0
2
3
5 7 10
Output power, PO -- W
2
3
5
JK470820
2
3
5 7 0.1
2 3
5 7 1.0
2
3
5 7 10
Output power, PO -- W
2
3
Current drain, ICC -- A
PO -- f
24
2
5 7
JK470821
No. A1783-7/9
LA4708N
VN -- VCC
12
200
RL = Open
Rg = 0
180
Quiescent current, ICCO -- mA
Output pin voltage, VN -- V
10
8
6
4
2
ICCO -- Ta
VCC = 13.2V
RL = Open
Rg = 0
160
140
120
100
80
60
40
20
0
0
4
8
12
16
20
24
Supply voltage, VCC -- V
PO -- Ta
36
Total harmonic distortion, THD -- %
Output power, PO -- W
32
RL = 2
Ω
30
26
24
VCC = 13.2V
Rg = 600Ω
f = 1kHz
THD = 10%
Dual channel drive
22
RL = 4Ω
20
18
16
-40
-20
0
20
40
60
Ambient temperature, Ta -- °C
80
0
20
60
80
100
JK470823
THD -- Ta
VCC = 13.2V
RL = 4Ω
Rg = 600Ω
f = 1kHz
PO = 2W
Dual channel drive
3
2
0.1
7
5
3
2
-40
100
40
Ambient temperature, Ta -- °C
-20
0
20
40
60
Ambient temperature, Ta -- °C
JK470824
VN -- VST
8
-20
5
34
28
0
-40
28
JK470822
80
100
JK470825
Amp ON time -- C3
1.2
7
Amp ON time -- s
Output pin voltage, VN -- V
1.0
6
5
4
3
VCC = 13.2V
RL = 4Ω
Rg = 0
Apply VST to standby pin (pin 5)
through 10kΩ.
2
1
0
0
1
2
3
4
5
6
Standby pin applied voltage, VST -- V
7
0.8
0.6
0.4
0.2
8
JK470826
0
2
VCC = 13.2V
VST = 5V
(Apply to pin 5 through 10kΩ.)
3
5
7
10
2
C3 -- μF
3
5
7
100
2
JK470827
PS No. A1783-8/9
LA4708N
ORDERING INFORMATION
Device
LA4708N-E
Package
SIP18H
(Pb-Free)
Shipping (Qty / Packing)
15 / Fan-Fold
ON Semiconductor and the ON logo are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC owns the rights to a number
of patents, trademarks, copyrights, trade secrets, and other intellectual property. A listing of SCILLC’s product/patent coverage may be accessed at
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warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the
application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental
damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual
performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical
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as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in
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PS No. A1783-9/9
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