LA4628 - ON Semiconductor

Ordering number : EN6632A
LA4628
Monolithic Linear IC
20W 2-Channel BTL Power Amplifier
for General Audio
http://onsemi.com
Overview
The LA4628 is a 2-channel general-purpose BTL audio power amplifier provided in a miniature package. 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.
Note that this device is pin compatible with the 13.5W×2-channel LA4625, and allows end products differentiated by
their power rating to share the same printed circuit board.
Features
• Total output : 20W+20W (at VCC = 13.5V, RL = 4Ω, THD = 10%)
• High-fidelity design (fL < 10Hz, fH = 130kHz)
• Extremely low impulse noise levels
• An arbitrary amplifier startup time can be set up with external components.
• Full complement of built-in protection circuits (includes circuits that protect against shorting to VCC, shorting to
ground, load shorting, overvoltages and excessive temperatures)
Specifications
Maximum Ratings at Ta = 25°C
Parameter
Symbol
Conditions
Maximum supply voltage
VCC max
No signal
Maximum output current
IO peak
Per channel
Allowable power dissipation
Pd max
With an arbitrarily large heat sink
Operating temperature
Storage temperature
Ratings
Unit
24
V
4
A
32.5
W
Topr
-20 to +85
°C
Tstg
-40 to +150
°C
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
O0808 MS JK/92900RM(OT) No.6632-1/8
LA4628
Operating Conditions at Ta = 25°C
Symbol
Parameter
Conditions
Ratings
Unit
Recommended supply voltage
VCC
13.5
V
Recommended load resistance range
RL op
4 to 8
Ω
Allowable operating supply voltage range
VCC op
9 to 20
V
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 = 13.5V, RL = 4Ω, f = 1kHz, Rg = 600Ω
Ratings
Parameter
Symbol
Conditions
min
Quiescent current
ICCO
With Rg = 0 and RL open.
Standby mode current drain
Ist
Standby mode (amplifier off), with no power
typ
70
Unit
max
130
250
mA
10
60
μA
40
42
dB
0.06
0.2
supply capacitor.
Voltage gain
VG
VO = 0dBm
Total harmonic distortion
THD
PO = 1W, Filter = FLAT
38
Output power
PO1
VCC = 13.5V, THD = 10%, RL = 4Ω
16
%
20
PO2
VCC = 16.5V, THD = 10%, RL = 4Ω
Output offset voltage
VN offset
Rg = 0
Output noise voltage
VNO
Rg = 0, BPF = 20Hz to 20kHz
Ripple rejection ratio
SVRR
Rg = 0, VR = 0dBm, fR = 100Hz
40
50
Channel separation
CHsep
Rg = 10kΩ, VO = 0dBm
50
60
Input resistance
Ri
21
30
Standby pin applied voltage
VST
W
30
W
-300
0.1
Amplifier on
+300
mV
0.5
mV
dB
dB
39
2.5
KΩ
VCC
V
(applied through an external 10kΩ resistor)
Package Dimensions
unit : mm (typ)
3113B
Allowable power dissipation, Pd max -- W
35
32.5
Pd max -- Ta
AI heat sink Mounting
torque 39N cm Flat
washer Silicone grease
applied
Infinite heat sink
30
25
20.83
20
θf = 3˚C/W
θf = 4˚C/W
θjc = 2˚C/W
15
13.9
10.4
10
5
3.1
θf = 7˚C/W
θf = 10˚C/W
Νο Fin
0
-20
0
20
40
60
80
100
120
140
160
Ambient temperature, Ta -- ˚C
No.6632-2/8
LA4628
Block Diagram
C2
100μF/16V
+
C5
14
2
OUTPUT PIN TO VCC
SHORT PROTECTOR
PREDRIVER
PRE GND
3
R1
ON 10KΩ
OFF
STANDBY
SW
THERMAL
SHUT DOWN
PREDRIVER
6
+
2.2μF
10V
–
9
POWER
LOAD SHORT
PROTECTOR
IN
PREDRIVER
C7**
0.1μF
+OUT1
+
OUTPUT PIN TO GND
SHORT PROTECTOR
IN2
POWER
GND2
10
8
POWER
–
-OUT2
C8**
RL
4Ω
R4
R5
C9**
+OUT2
+
OUTPUT PIN TO VCC
SHORT PROTECTOR
POP NOISE
PREVENTION
CIRCUIT
5
+
7
C3
0.47μF
10V
+
R3
**
(POLYESTER FILM
CAPACITOR)
VCC
4
RL
4Ω
R2
OUTPUT PIN TO GND
SHORT PROTECTOR
+5V
C4
12
11
POWER
OVER VOLTAGE /
SURGE PROTECTOR
BIAS
CIRCUIT
33μF
10V
Standby
SW
POWER
GND1
LOAD SHORT
PROTECTOR
IN
C6**
2.2Ω 2.2Ω
–
0.1μF
+
–
-OUT1
2.2Ω 2.2Ω
1
2.2μF
10V
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.6632-3/8
LA4628
Pin Voltages
VCC = 13.5V, 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
1.55V
6.63V
0V
3.21V
2.32V
1.55V
2.07V
Pin No.
8
9
10
11
12
13
14
Pin name
+OUT2
-OUT2
PWR–GND
+OUT1
PWR–GND
-OUT1
VCC
Pin voltage
6.6V
6.5V
0V
6.5V
0V
6.6V
13.5V
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 LA4628 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 13.5V 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 13.5V 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 =
<applied voltage>−1.4
500μA
Pin 4 Internal Equivalent Circuit
500μA or lower
10kΩ
4
R1
Applied standby
voltage
About 1.4V
(2VBE)
−10kΩ
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.
No.6632-4/8
LA4628
3. Impulse noise improvements
• While the LA4628 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.)
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 LA4628 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 LA4628 also includes other protection circuits. Use of these circuits also requires care during end product
design and testing.
5. Other notes
• The LA4628 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
C5
VCC
14
1
+
LA4628
C1
IN1
+
+
C2
-OUT1
R2
C6
STB
GND
R1
+OUT1
R3
+
+
C3
IN2
C7
C4
+
C10
-OUT2
GND
R4
C8
R5
C9
+OUT2
No.6632-5/8
LA4628
PO -- VCC
40
35
30
Output power, PO -- W
Output power, PO -- W
100
7
5
3
2
f = 1kHz
Rg = 600Ω
THD = 10%
Ω
25
=4
RL
20
RL
=6
Ω
15
10
5
0
6
7
8
9
10
11
12
13
14
15
16
17
PO -- f
THD = 10%
Response -- dB
10
5
3
2
2 3
5 7 1k
2 3
Frequency, f -- Hz
5 7 10k
2 3
THD -- PO
1.0
7
5
10kHz
3
2
0.1
7
5
100Hz
1kHz
3
2
2
3
5 7 1.0
2
3
5 7 10
2
3
Output power, PO -- W
VCC = 13.5V
RL = 4Ω
RO = 1W
3
2
1.0
7
5
3
2
0.1
7
5
3
2
0.01
10
3
5 7 10
2
3
5 7 100
2
3
Input voltage, VIN -- mVrms
5 7 1k
f Response
-4
-6
10
7
5
3
2
VCC = 13.5V
RL = 4Ω
Rg = 600Ω
VO = 0dBm at 1kHz
2 3
5 7 100
2 3
5 7 1k
2 3
Frequency, Ta -- °C
5 7 10k
2 3
5 7100k
THD -- PO
VCC = 13.5V
RL = 6Ω
Rg = 600Ω
1.0
7
5
3
2
10kHz
0.1
7
5
1kHz
3
2
0.01
0.1
5 7 100
THD -- f
10
7
5
2
-2
-10
10
5 7100k
VCC = 13.5V
RL = 4Ω
Rg = 600Ω
0.01
0.1
Total harmonic distortion, THD -- %
5 7 100
0.1
7
5
3
2
-8
Total harmonic distortion, THD -- %
Total harmonic distortion, THD -- %
10
7
5
VCC = 13.5V
RL = 4Ω
Rg = 600Ω
100Hz
2
3
5
7 1.0
2
3
5
7 10
2
3
Output power, PO -- W
5
7 100
CHsep -- f
0
VCC = 13.5V
RL = 4Ω
Rg = 10kΩ
VO = 0dBm
-10
Channel separation, CHsep -- dB
Output power, PO -- W
THD = 1%
2 3
1.0
7
5
3
2
0
THD = 3%
0
10
10
7
5
3
2
2
20
15
VCC = 13.5V
RL = 4Ω
f = 1kHz
0.01
1.0
18
Supply voltage, VCC -- V
25
PO -- VIN
-20
-30
-40
-50
CH12
-60
CH21
-70
-80
2 3
5 7 100
2 3
5 7 1k
2 3
Frequency, f -- Hz
5 7 10k
2 3
5 7100k
-90
10
2 3
5 7 100
2 3
5 7 1k
2 3
Frequency, f -- Hz
5 7 10k
2 3
5 7100k
No.6632-6/8
LA4628
Output noise voltage, VNO -- mVrms
7
5
VNO -- Rg
3
2
0.1
7
5
3
2
0.01
100
2
3
5
7 1k
2
3
5
SVRR -- VCC
0
VCC = 13.5V
RL = 4Ω
DIN AUDIO
Ripple rejection ratio, SVRR -- dB
1.0
7 10k
2
3
5
-20
-40
OUT1
OUT2
-60
-80
-100
-120
7 100k
Rg = 0
fR = 100Hz
VCCR = 0dBm
5
7
9
Signal source resistance, Rg -- Ω
VCC = 13.5V
RL = 4Ω
Rg = 0Ω
-40
100Hz OUT1
100Hz OUT2
-60
3kHz OUT2
3kHz OUT1
-80
Calculated at SVRR = 20log
-100
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
VO
VCCR
1.8
Pd -- PO (RL = 4Ω)
)
5V
(1
Pd
16
3.
(1
6.5
V)
20
19
21
23
12
VCC = 13.5V
RL = 4Ω
Rg = 0
VCCR = 0dBm
OUT1
-60
OUT2
-80
2 3
5 7 100
2 3
5 7 1k
2 3
5 7 10k
2 3
Ripple frequency, fR -- Hz
5 7100k
Pd -- PO (RL = 6Ω)
RL = 6Ω
Rg = 600Ω
f = 1kHz
Calculated at
Pd = (VCC × ICC) - (2PO)
28
Power dissipation, Pd -- W
24
17
-40
32
RL = 4Ω
Rg = 600Ω
f = 1kHz
Calculated at
Pd = (VCC × ICC) - (2PO)
Pd
Power dissipation, Pd -- W
28
15
-20
-100
10
2.0
Power supply ripple, VCCR -- Vrms
32
13
SVRR -- fR
0
Ripple rejection ratio, SVRR -- dB
Ripple rejection ratio, SVRR -- dB
SVRR -- VCCR
-20
11
Supply voltage, VCC -- V
24
20
V)
6.5
18
1
d(
P
12
Pd
)
.5V
(13
8
4
0
0.1
2
3
5 7 1.0
2
3
5 7 10
2
3
5 7 100
Output power, PO -- W/CH
6
2
3
5
7 1.0
2
3
5
7 10
2
3
5 7 100
Output power, PO -- W/CH
ICC -- PO
RL = 4/6Ω
Rg = 600Ω
f = 1kHz
R
L=
4Ω
4
3
R
L=
6Ω
Current drain, ICC -- A
5
0
0.1
2
1
0
0.1
2
3
5 7 1.0
2
3
5 7 10
Output power, PO -- W/CH
2
3
5 7 100
No.6632-7/8
LA4628
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PS No.6632-8/8