EN5715 D
Ordering number : EN5715A
LA4725
Monolithic Linear IC
2-channel 30W BTL Audio
Amplifier
http://onsemi.com
Overview
The LA4725 is a 2-channel BTL audio power amplifier IC for Car audio. It was designed for the best possible audio
quality and features an extended low band roll-off frequency provided by a newly-developed NF circuit that does not
require an external capacitor. Furthermore, crosstalk, which can cause muddiness in the audio output, has been
significantly reduced by both circuit and wiring pattern improvements. Thus this amplifier can provide powerful lows
and clear highs.
Features
• Total output (EIAJ power): 30W+30W (at VCC = 14.4V, RL = 4Ω, THD = 30%)
• High-fidelity design (fL < 10Hz, fH = 130kHz)
• Extremely low impulse noise levels
• An arbitrary amplifier startup time can be set up with external components
• built-in standby switch circuit
• Full complement of built-in protection circuits (includes circuits that protect against shorting to VCC, shorting to
ground, load shorting, over-voltages and excessive temperatures)
Specifications
Maximum Ratings at Ta = 25°C
Parameter
Symbol
Maximum supply voltage
VCC max
No signal
Conditions
Ratings
18
Unit
Surge supply voltage
VCC surge
t ≤ 0.2s, Giant pulse one-shot
50
V
Maximum output current
IO peak
Per channel
3.0
A
Allowable power dissipation
Pd max
With a infinite heat sink
32
W
Operating temperature
Topr
-35 to +85
°C
Storage temperature
Tstg
-40 to +150
°C
V
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating
Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability.
Semiconductor Components Industries, LLC, 2013
May, 2013
40109 MS JK 20090313-S00003 No.5715-1/8
LA4725
Operating Conditions at Ta = 25°C
Parameter
Symbol
Recommended supply voltage
VCC
Allowable operating supply voltage
VCC op
Recommended load resistance
RL
Conditions
Ratings
Unit
13.2
V
9 to 16
V
4
Ω
Note : With VCC, RL, and the output level in ranges such that the Pd max for the heat sink used is not exceeded.
Electrical Characteristics at Ta = 25°C, VCC = 13.2V, RL = 4Ω, f = 1kHz, Rg = 600Ω
Ratings
Parameter
Symbol
Conditions
min
Quiescent current
ICCO
Rg = 0
Standby mode current drain
Ist
Standby mode (amplifier off), with no power
typ
70
Unit
max
125
250
mA
10
60
µA
40
42
dB
0.06
0.2
supply capacitor.
Voltage gain
VG
VO = 0dBm
Total harmonic distortion
THD
PO = 2W
Output power
PO1
THD = 10%
PO2
PO3
VN offset
Rg = 0
Output offset voltage
38
13
%
17
W
THD = 10%, VCC = 14.4V
20
W
THD = 30%, VCC = 14.4V
30
-300
W
+300
mV
0.5
mV
Output noise voltage
VNO
Rg = 0, BPF = 20Hz to 20kHz
Ripple rejection ratio
SVRR
Rg = 0, VR = 0dBm, fR = 100Hz
40
0.1
50
dB
Channel separation
CHsep
Rg = 10kΩ, VO = 0dBm
50
60
dB
Input resistance
Ri
21
30
Standby pin applied voltage
VST
Amplifier on
2.5
39
kΩ
VCC
V
(applied through an external 10kΩ resistor)
Package Dimensions
unit : mm (typ)
3113B
26.8
HEAT SPREADER
(20.0)
4.0
7.8
14.5MAX
1
(1.83)
5.2
4.6
7.0
(11.8)
(8.4)
(R1.7)
14
1.78
0.5
0.8
0.4
1.6
2.2
Allowable power dissipation, Pd max -- W
35
32.5
Pd max -- Ta
Infinite heat sink
AI heat sink Mounting
torque 39N • cm
Flat washer Silicone
grease applied
30
25
20.83
20
15
13.9
10.4
10
5
3.1
0
-40
θf = 3°C/W
θf = 4°C/W
θjc = 2°C/W
θf = 7°C/W
θf = 10°C/W
Νο Fin
-20
0
20
40
60
80
100
120
140
160
Ambient temperature, Ta -- °C
SANYO : SIP14HZ
No.5715-2/8
LA4725
Block Diagram
C2
100μF/25V
+
C5
14
2
OUTPUT PIN TO VCC
SHORT PROTECTOR
PREDRIVER
PRE GND
3
R1
ON 10KΩ
OFF
POWER
GND1
LOAD SHORT
PROTECTOR
IN
11
POWER
STANDBY
SW
THERMAL
SHUT DOWN
9
POWER
IN2
+
6
+
2.2μF
25V
−
LOAD SHORT
PROTECTOR
IN
PREDRIVER
+
POWER
GND2
0.1μF
10
8
POWER
ñ
-OUT2
C8**
RL
4Ω
R4
R5
C9**
+OUT2
+
OUTPUT PIN TO VCC
SHORT PROTECTOR
POP NOISE
PREVENTION
CIRCUIT
7
5
33μF
25V
+
C3
0.47μF
25V
C4
C7**
+OUT1
OUTPUT PIN TO GND
SHORT PROTECTOR
+5V
PREDRIVER
R3
**
(POLYESTER FILM
CAPACITOR)
VCC
4
RL
4Ω
R2
OUTPUT PIN TO GND
SHORT PROTECTOR
OVER VOLTAGE /
SURGE PROTECTOR
BIAS
CIRCUIT
12
C6**
2.2Ω 2.2Ω
−
0.1μF
+
ñ
-OUT1
2.2Ω 2.2Ω
1
2.2μF
25V
13
POWER
0.1μF
PREDRIVER
0.1μF
RIPPLE
FILTER
C1
+
+
2200μF
25V
VCC
+
C10
C3
Sets the amplifier starting time
(Approximately 0.6 seconds when 33µF)
C10
Impulse noise reduction
(Note : The device’s ability to withstand shorting
to VCC or shorting to ground when VCC is
around 16V may be reduced as the value of this
capacitor is increased. We recommend 0.47µF.)
No.5715-3/8
LA4725
Pin Voltages
VCC = 13.2V, with 5V applied to STBY through a 10kΩ resistor, RL = 4Ω, Rg = 0
Pin No.
1
2
3
4
5
6
7
Pin name
IN1
DC
PRE-GND
STBY
ON TIME
IN2
POP
Pin voltage
1.53V
5.65V
0V
3.25V
2.32V
1.53V
2.14V
Pin No.
8
9
10
11
12
13
14
Pin name
+OUT2
−OUT2
PWR-GN
+OUT1
PWR-GN
−OUT1
VCC
Pin voltage
5.70V
5.70V
0V
5.70V
0V
5.70V
13.2V
External Components
C1 and C4: Input capacitors. A value of 2.2μF is recommended. Determine the polarity based on the DC potential of
the circuit connected directly to the LA4725 front end. Note that the low band response can be adjusted by
varying fL with the capacitors C1 and C4.
C2
: Decoupling capacitor (ripple filter)
C3
: Sets the amplifier starting time, which will be approximately 0.6 seconds for a value of 33μF. The starting
time is proportional to the value of this capacitor, and can be set to any desired value.
C5
: Power-supply capacitor
C6, C7, C8, and C9 :
Oscillation prevention capacitors. Use polyester film capacitors (Mylar capacitors) with excellent
characteristics. (Note that the series resistors R2, R3, R4, and R5 are used in conjunction with these
capacitors to achieve stable amplifier operation.) A value of 0.1μF is recommended.
C10
: Impulse noise reduction capacitor. A value of 0.47μF is recommended. Caution is required when selecting
the value for this capacitor, since increasing its value influences the operation of the circuits that protect
against shorting the amplifier output pins to VCC or to ground when higher VCC voltages (approximately
16V or higher) are used.
R1
: Standby switch current limiting resistor. A value of 10kΩ is recommended when a voltage in the range 2.5 to
12V will be applied as the standby switching voltage. Note that this resistor is not optional: it must be included.
IC Internal Characteristics and Notes
1. Standby function
• Pin 4 is the standby switch. A voltage of 2.5V or
higher must be applied through an external resistor to
turn the amplifier on.
• If a voltage of over 12V will be applied as the
standby mode switching voltage, use the following
formula to determine the value of R1 so that the
current entering at pin 4 remains under 500μA.
R1 =
Pin 4 Internal Equivalent Circuit
500μA or lower
10kΩ
4
R1
Applied standby
voltage
About 1.4V
(2VBE)
<applied voltage> − 1.4
− 10kΩ
500μA
2. Muting function
• Pin 5 connects the capacitor that determines the starting time to prevent impulse noise. It can also be used to mute
the amplifier output by shorting pin 5 to ground. When this function is used, the recovery time depends on C3.
3. Impulse noise improvements
• While the LA4725 achieves a low level of impulse noise, if even further reductions in impulse noise at power
on/off (and when switching into or out of standby mode) a 0.47μF capacitor may be inserted between pin 7 and the
PRE GND pin (pin 3). (Pin 7 is the output amplifier bias pin. Since the ability to withstand shorting the output pins
to VCC or ground is reduced for supply voltages over 16V if the pin 7 capacitance is large, we recommend a value
of 0.47μF or lower for this capacitor.)
No.6631-4/8
LA4725
4. Protection circuits
• Due to the system structure of the protection circuit for shorts to VCC or ground, if there is a DC resistance
between the amplifier output pins and ground, the protection circuit may operate when power is first applied and
the amplifier may fail to turn on. The basic design approach we recommend is not to adopt any designs in which
there is a DC resistance between the amplifier outputs and ground.
• The LA4725 includes a built-in thermal protection circuit to prevent the IC from being damaged or destroyed if
abnormally high temperatures occur. This thermal protection circuit gradually reduces the output if the IC
junction temperature (Tj) reaches the range 170 to 180°C due to inadequate heat sinking or other problem. If the
temperature falls, the amplifier will restart automatically.
• The LA4725 also includes other protection circuits. Use of these circuits also requires care during end product
design and testing.
5. Other notes
• The LA4725 is a BTL power amplifier. When testing this device, the ground systems for the test equipment
connected to IC inputs, and that for the test equipment connected to IC outputs, must be isolated. Do not use a
common ground.
Printed Circuit Pattern
(copper foil side)
GND
VCC
C5
+
14
1 LA4625/LA4725
C1
IN1
+
R2
C6
-OUT1
GND
+
C2
STB
R1
R3
C7
+OUT1
+
+
C3
IN2
C4
+
C10
GND
R4
C8
R5
C9
-OUT2
+OUT2
No.6631-5/8
LA4725
PO -- VCC
40
f = 1kHz
Rg = 600Ω
RL = 4Ω
30
Output power, PO -- W
Output power, PO -- W
35
%
25
=
HD
30
T
20
0%
D
=1
TH
15
10
5
0
6
7
8
9
10
11
12
13
PO -- VIN
100
7
5
3
2
14
15
16
17
VCC = 13.2V
RL = 4Ω
f = 1kHz
10
7
5
3
2
1.0
7
5
3
2
0.1
7
5
3
2
0.01
1.0
18
2
3
5
Output power, PO -- W
20
PO -- f
THD = 3%
12
THD = 1%
8
2 3
5 7 100
2 3
5 7 1k
2 3
5 7 10k
2 3
2
THD -- PO
1.0
7
5
3
2
f = 1kHz
0.1
7
5
10kHz
100Hz
3
2
2
3
2 3
5 7 100
5 7 1.0
2
3
5 7 10
2
3
5 7 100
CHsep -- f
CH1→2
-50
CH2→1
-60
-70
3
2
2 3
5 7 1k
2 3
Frequency, f -- Hz
5 7 10k
2 3
5 7100k
1.0
7
5
3
2
0.1
7
5
3
2
2 3 5 7 100
2 3 5 7 1k
2 3 5 7 10k
2 3 5 7100k
VNO --VCC
5 7 10k
2 3
5 7100k
Rg = 0
RL = 4Ω
110
100
90
80
70
60
5 7100
2 3
VCC = 13.2V
RL = 4Ω
PO = 1W
Nonfilter
120
-40
2 3
5 7 1k
Frequency, f -- Hz
VCC = 13.2V
RL = 4Ω
Rg = 10kΩ
VO = 0dBm
Nonfilter
-80
10
2 3
THD -- f
10
7
5
0.01
10
Output noise voltage, VNO -- mVrms
Channel separation, CHsep -- dB
-30
7 1k
VCC = 13.2V
RL = 4Ω
Rg = 600Ω
VO = 0dBm (f = 1kHz)
Output power, PO -- W
-20
5
Frequency, f -- Hz
VCC = 13.2V
RL = 4Ω
Rg = 600Ω
DIN AUDIO
0.01
0.1
3
-6
-10
10
5 7100k
Total harmonic distortion, THD -- %
Total harmonic distortion, THD -- %
3
2
-4
Frequency, f -- Hz
10
7
5
7 100
-2
-8
4
0
10
5
0
THD = 10%
16
3
f Response
2
VCC = 13.2V
RL = 4Ω
Rg = 600Ω
Response -- dB
24
2
7 10
Input voltage, VIN -- mVrms
Supply voltage, VCC -- V
8
10
12
14
16
18
Supply voltage, VCC -- V
No.6631-6/8
LA4725
SVRR -- VCC
-30
-40
OUT1
-50
-60
SVRR -- VCCR
0
RL = 4Ω
Rg = 0
fR = 100Hz
VCCR = 0dBm
DIN AUDIO
Ripple rejection ratio, SVRR -- dB
Ripple rejection ratio, SVRR -- dB
-20
OUT2
-70
VCC = 13.2V
RL = 4Ω
Rg = 0
Nonfilter
-20
-40
100Hz
OUT1
T2
z OU
UT1
3kHz O
-60
100H
T2
3kHz OU
-80
SVRR = 20log
-80
8
6
10
12
14
16
-100
18
0
0.2
0.4
SVRR -- fR
Quiescent current, ICCO -- mA
Ripple rejection ratio, SVRR -- dB
OU
T1
OUT
2
-80
-100
10
2 3
5 7 100
2 3
5 7 1k
2 3
5 7 10k
2 3
2.0
100
80
60
25
Power dissipation, Pd -- W
10
8
VN -- V
1.8
6
8
10
12
6
4
2
10
15
20
14
16
18
20
22
36
36
36
3
5
36
Supply voltage, VCC -- V
RL = 4Ω
Rg = 0
25
30
Pd -- PO
RL = 4Ω
Rg = 600Ω
f = 1kHz
20
V
.4
15
=
C
VC
10
V
14
V
3.2
=1
CC
5
0
0.1
2
3
5
7 1.0
2
3
5
7 10
2
7 100
Output power, PO -- W
Supply voltage, VCC -- V
Amp ON time
0.6
1.6
120
40
5 7100k
VN -- VCC
12
5
1.4
140
Ripple frequency, fR -- Hz
0
1.2
RL = 4Ω
Rg = 0
-40
-60
1.0
ICCO -- VCC
160
VCC = 13.2V
RL = 4Ω
Rg = 0
VCCR = 0dBm
Nonfilter
-20
0.8
Power supply ripple, VCCR -- Vrms
Supply voltage, VCC -- V
0
0.6
VO
VCCR
VCC = 13.2V
VST = 5V
Amp ON time -- s
0.5
0.4
0.3
0.2
0.1
0
1.0
2
3
5
7
10
2
3
5
7
100
C3 -- μF
No.6631-7/8
LA4725
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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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PS No.5715-8/8
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