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
Maximum supply voltage
Surge supply voltage
Maximum output current
Allowable power dissipation
Operating temperature
Storage temperature
Symbol
VCC max
VCC surge
IO peak
Pd max
Topr
Tstg
No signal
t
≤
0.2s, Giant pulse one-shot
Per channel
With a infinite heat sink
Conditions
Ratings
18
50
3.0
32
-35 to +85
-40 to +150
Unit
V
V
A
W
°C
°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
40109 MS JK 20090313-S00003 No.5715-1/8
LA4725
Operating Conditions
at Ta = 25°C
Parameter
Recommended supply voltage
Allowable operating supply voltage
Recommended load resistance
Symbol
VCC
VCC op
RL
Conditions
Ratings
13.2
9 to 16
4
Unit
V
V
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
Quiescent current
Standby mode current drain
Voltage gain
Total harmonic distortion
Output power
Symbol
ICCO
Ist
VG
THD
PO1
PO2
PO3
Output offset voltage
Output noise voltage
Ripple rejection ratio
Channel separation
Input resistance
Standby pin applied voltage
VN offset
VNO
SVRR
CHsep
Ri
VST
Amplifier on
(applied through an external 10kΩ resistor)
Rg = 0
Standby mode (amplifier off), with no power
supply capacitor.
VO = 0dBm
PO = 2W
THD = 10%
THD = 10%, VCC = 14.4V
THD = 30%, VCC = 14.4V
Rg = 0
Rg = 0, BPF = 20Hz to 20kHz
Rg = 0, VR = 0dBm, fR = 100Hz
Rg = 10kΩ, VO = 0dBm
40
50
21
2.5
-300
0.1
50
60
30
39
VCC
13
38
40
0.06
17
20
30
+300
0.5
42
0.2
dB
%
W
W
W
mV
mV
dB
dB
kΩ
V
Conditions
min
70
typ
125
10
max
250
60
Unit
mA
µA
Package Dimensions
unit : mm (typ)
3113B
35
Pd max -- Ta
Infinite heat sink
Allowable power dissipation, Pd max -- W
26.8
(20.0)
(R1.7)
(8.4)
32.5
30
HEAT SPREADER
4.0
25
20.83
20
θf
= 3°C/W
θf
= 4°C/W
AI heat sink Mounting
torque 39N
•
cm
Flat washer Silicone
grease applied
θjc
= 2°C/W
(11.8)
14.5MAX
15
13.9
10.4
10
7.8
θf
= 7°C/W
θf
= 10°C/W
7.0
4.6
5.2
1
(1.83)
1.78
0.5
14
0.8
0.4
1.6
2.2
5
3.1
0
-40
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
+
VCC
2
RIPPLE
FILTER
14
OUTPUT PIN TO VCC
SHORT PROTECTOR
0.1μF
PREDRIVER
C1
+
2.2μF
25V
POWER
13
LOAD SHORT
PROTECTOR
POWER
GND1
-OUT1
C6**
1
+
−
2.2Ω 2.2Ω
2200μF
25V
ñ
IN
12
0.1μF
R2
R3
RL
4Ω
PREDRIVER
POWER
11
OUTPUT PIN TO GND
SHORT PROTECTOR
C7**
+OUT1
+
PRE GND
3
BIAS
CIRCUIT
OVER VOLTAGE /
SURGE PROTECTOR
VCC
R1
ON 10KΩ
OFF
+5V
**
(POLYESTER FILM
CAPACITOR)
OUTPUT PIN TO GND
SHORT PROTECTOR
-OUT2
4
STANDBY
SW
THERMAL
SHUT DOWN
0.1μF
PREDRIVER
C4
IN2
+
POWER
LOAD SHORT
PROTECTOR
9
POWER
GND2
ñ
C8**
6
+
−
2.2Ω 2.2Ω
0.1μF
2.2μF
25V
IN
10
8
R4
R5
RL
4Ω
PREDRIVER
POWER
C9**
+OUT2
+
OUTPUT PIN TO VCC
SHORT PROTECTOR
POP NOISE
PREVENTION
CIRCUIT
5
33μF
25V
+
7
0.47μF
25V
C3
+
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.
Pin name
Pin voltage
1
IN1
1.53V
2
DC
5.65V
3
PRE-GND
0V
4
STBY
3.25V
5
ON TIME
2.32V
6
IN2
1.53V
7
POP
2.14V
Pin No.
Pin name
Pin voltage
8
+OUT2
5.70V
9
−OUT2
5.70V
10
PWR-GN
0V
11
+OUT1
5.70V
12
PWR-GN
0V
13
−OUT1
5.70V
14
VCC
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 =
<applied
voltage>
−
1.4
−
10kΩ
500μA
Pin 4 Internal Equivalent Circuit
500μA or lower
10kΩ
4
R1
Applied standby
voltage
About 1.4V
(2VBE)
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
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