STMICROELECTRONICS TDA7294S

TDA7294S
100V - 100W DMOS AUDIO AMPLIFIER WITH MUTE/ST-BY
1
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■
■
■
■
■
■
■
■
■
■
■
2
Features
Figure 1. Package
VERY HIGH OPERATING VOLTAGE RANGE
(± 45V)
MULTIPOWER BCD TECHNOLOGY
DMOS POWER STAGE
HIGH OUTPUT POWER (100W @ THD = 10%,
RL = 8Ω, VS = ±40V (MUSIC POWER)
MUTING/STAND-BY FUNCTIONS
NO SWITCH ON/OFF NOISE
VERY LOW DISTORTION
VERY LOW NOISE
SHORT CIRCUIT PROTECTED (WITH NO
INPUT SIGNAL APPLIED)
THERMAL SHUTDOWN
CLIP DETECTOR
MODULARITY (MORE DEVICES CAN BE
EASILY CONNECTED IN PARALLEL TO
DRIVE VERY LOW IMPEDANCES)
Multiwatt15 (Vertical)
Table 1. Order Codes
Part Number
Package
TDA7294S
Multiwatt15 (Vertical)
class AB amplifier in Hi-Fi field applications (Home
Stereo, self powered loudspeakers, Top class
TV). Thanks to the wide voltage range and to the
high out current capability it is able to supply the
highest power into both 4Ω and 8Ω loads. The built
in muting function with turn on delay simplifies the
remote operation avoiding switching on-off noises.
Parallel mode is made possible by connecting
more device through of pin11. High output power
can be delivered to very low impedance loads, so
optimizing the thermal dissipation of the system.
Description
The TDA7294S is a monolithic integrated circuit in
Multiwatt15 package, intended for use as audio
Figure 2. Typical Application and Test Circuit
+Vs
C7 100nF
C6 1000µF
R3 22K
C2
22µF
BUFFER DRIVER
+Vs
R2
680Ω
C1 470nF
IN-
2
IN+
3
+PWVs
11
7
13
-
R5 10K
MUTE
STBY
BOOT
LOADER
C5
22µF
6
10
5
THERMAL
SHUTDOWN
MUTE
VSTBY
12
4
(**)
VMUTE
OUT
+
R1 22K
SGND
14
9
S/C
PROTECTION
(*)
BOOTSTRAP
CLIP DET
VCLIP
STBY
R4 22K
C3 10µF
C4 10µF
1
8
15
STBY-GND
-Vs
-PWVs
C9 100nF
C8 1000µF
D97AU805A
(*) see Application note
(**) for SLAVE function
February 2005
-Vs
Rev. 2
1/16
TDA7294S
Figure 3. Pin Connection (Top view)
15
-VS (POWER)
14
OUT
13
+VS (POWER)
12
BOOTSTRAP LOADER
11
BUFFER DRIVER
10
MUTE
9
STAND-BY
8
-VS (SIGNAL)
7
+VS (SIGNAL)
6
BOOTSTRAP
5
CLIP AND SHORT CIRCUIT DETECTOR
4
SIGNAL GROUND
3
NON INVERTING INPUT
2
INVERTING INPUT
1
STAND-BY GND
TAB CONNECTED TO PIN 8
D97AU806
Table 2. Quick Reference Data
Symbol
VS
GLOOP
Ptot
SVR
Parameter
Test Condition
Min.
Typ.
Max.
Unit
Supply Voltage Operating
±12
±45
V
Closed Loop Gain
26
45
dB
Output Power
VS = ± 40V; RL = 8Ω; THD = 10%
100
W
VS = ± 40V; RL = 8Ω; THD = 10%
100
W
75
dB
Supply Voltage Rejection
Table 3. Thermal Data
Symbol
Rth j-case
2/16
Parameter
Thermal Resistance Junction-case
Typ
Max
Unit
1
1.5
°C/W
TDA7294S
Table 4. Absolute Maximum Ratings
Symbol
Parameter
Value
Unit
VS
Supply Voltage (No Signal)
±50
V
V1
VSTAND-BY GND Voltage Referred to -VS (pin 8)
90
V
V2
Input Voltage (inverting) Referred to -VS
90
V
V2 - V3
Maximum Differential Inputs
±30
V
V3
Input Voltage (non inverting) Referred to -VS
90
V
V4
Signal GND Voltage Referred to -VS
90
V
V5
Clip Detector Voltage Referred to -VS
100
V
V6
Bootstrap Voltage Referred to -VS
100
V
V9
Stand-by Voltage Referred to -VS
100
V
V10
Mute Voltage Referred to -VS
100
V
V11
Buffer Voltage Referred to -VS
100
V
V12
Bootstrap Loader Voltage Referred to -VS
90
V
Output Peak Current
10
A
IO
Ptot
Power Dissipation Tcase = 70°C
Top
Operating Ambient Temperature Range
Tstg, Tj
Storage and Junction Temperature
50
W
0 to 70
°C
150
°C
Table 5. Electrical Characteristcs
(Refer to the Test Circuit VS = ±35V, RL = 8Ω, GV = 30dB; Rg = 50Ω; Tamb = 25°C, f = 1kHz; unless
otherwise specified).
Symbol
Parameter
Test Condition
Min.
Typ.
Max.
Unit
±45
V
65
mA
500
nA
VS
Operating Supply Range
±12
Iq
Quiescent Current
20
Ib
Input Bias Current
VOS
Input Offset Voltage
±10
mV
IOS
Input Offset Current
±100
nA
PO
RMS Continuous Output Power
d
d = 0.5%:
VS = ± 35V, RL = 8Ω
VS = ± 32V, RL = 6Ω
VS = ± 28V, RL = 4Ω
Music Power (RMS) (*)
∆t = 1s
d = 0.5%:
VS = ± 40V, RL = 8Ω
VS = ± 35V, RL = 6Ω
VS = ± 30V, RL = 4Ω (***)
Total Harmonic Distortion (**)
PO = 5W; f = 1kHz
PO = 0.1 to 20W; f = 20Hz to 20kHz
60
60
60
Overcurrent Protection Threshold
SR
Slew Rate
GV
Open Loop Voltage Gain
GV
Closed Loop Voltage Gain
VS ≤ ± 40V
70
70
70
W
W
W
100
100
100
W
W
W
0.005
VS = ± 28V, RL = 4Ω:
PO = 5W; f = 1kHz
PO = 0.1 to 20W; f = 20Hz to 20kHz
IMAX
30
0.1
%
%
0.1
%
%
0.01
6.5
7
A
10
V/µs
80
26
30
dB
45
dB
3/16
TDA7294S
Table 5. Electrical Characteristcs (continued)
(Refer to the Test Circuit VS = ±35V, RL = 8Ω, GV = 30dB; Rg = 50Ω; Tamb = 25°C, f = 1kHz; unless
otherwise specified).
Symbol
eN
fL, fH
Ri
SVR
TS
Parameter
Total Input Noise
Frequency Response (-3dB)
Test Condition
Min.
A = curve
f = 20Hz to 20kHz
2
PO = 1W
f = 100Hz; Vripple = 0.5Vrms
Max.
Unit
5
µV
µV
1
20Hz to 20kHz
Input Resistance
Supply Voltage Rejection
Typ.
60
Thermal Shutdown
100
kΩ
75
dB
150
°C
STAND-BY FUNCTION (Ref: -VS or GND)
VST on
Stand-by on Threshold
VST off
Stand-by off Threshold
3.5
Stand-by Attenuation
70
ATTst-by
Iq st-by
1.5
Quiescent Current @ Stand-by
V
V
90
1
dB
3
mA
1.5
V
MUTE FUNCTION (Ref: -VS or GND)
VMon
Mute on Threshold
VMoff
Mute off Threshold
3.5
Mute Attenuation
60
ATTmute
V
80
dB
10
%
CLIP DETECTOR
Duty
Duty Cycle ( pin 5)
THD = 1%; RL = 10KΩ to 5V
THD = 10%; RL = 10KΩ to 5V
ICLEAK
PO = 50W
30
40
50
%
3
µA
Note (*):
MUSIC POWER CONCEPT
MUSIC POWER is the maximal power which the amplifier is capable of producing across the rated load resistance (regardless of non linearity) 1 sec after the application of a sinusoidal input signal of frequency 1KHz.
Note (**): Tested with optimized Application Board (see fig. 3)
Note (***): Limited by the max. allowable current.
Note (***): For supply voltage ≥35V, The device could be demaged in short circuit conditions when the input signal is applied
4/16
TDA7294S
Figure 4. Typical Application P.C. Board and Component Layout (scale 1:1)
3
Application Suggestions (see Test and Application Circuits of the Fig. 2)
The recommended values of the external components are those shown on the application circuit of Figure
2. Different values can be used; the following table can help the designer.
Table 6. Application Suggestions
COMPONENTS
SUGGESTED
VALUE
PURPOSE
R1 (*)
22k
LARGER THAN
SUGGESTED
SMALLER THAN
SUGGESTED
INPUT RESISTANCE
INCREASE INPUT
IMPEDANCE
DECREASE INPUT
IMPEDANCE
CLOSED LOOP GAIN
SET TO 30dB (**)
DECREASE OF GAIN
INCREASE OF GAIN
INCREASE OF GAIN
DECREASE OF GAIN
R2
680Ω
R3 (*)
22k
R4
22k
ST-BY TIME
CONSTANT
LARGER ST-BY
ON/OFF TIME
SMALLER ST-BY ON/
ON/OFF TIME;
POP NOISE
R5
10k
MUTE TIME
CONSTANT
LARGER MUTE
ON/OFF TIME
SMALLER MUTE
ON/OFF TIME
C1
0.47µF
INPUT DC
DECOUPLING
HIGHER LOW
FREQUENCY
CUTOFF
C2
22µF
FEEDBACK DC
DECOUPLING
HIGHER LOW
FREQUENCY
CUTOFF
C3
10µF
MUTE TIME
CONSTANT
LARGER MUTE
ON/OFF TIME
SMALLER MUTE
ON/OFF TIME
5/16
TDA7294S
Table 6. Application Suggestions (continued)
COMPONENTS
SUGGESTED
VALUE
C4
PURPOSE
LARGER THAN
SUGGESTED
SMALLER THAN
SUGGESTED
10µF
ST-BY TIME
CONSTANT
LARGER ST-BY
ON/OFF TIME
SMALLER ST-BY ON/
ON/OFF TIME;
POP NOISE
C5
22µFXN (***)
BOOTSTRAPPING
C6, C8
1000µF
SUPPLY VOLTAGE
BYPASS
C7, C9
0.1µF
SUPPLY VOLTAGE
BYPASS
SIGNAL
DEGRADATION AT
LOW FREQUENCY
DANGER OF
OSCILLATION
(*) R1 = R3 for pop optimization
(**) Closed Loop Gain has to be ≥ 26dB
(***) Multiply this value for the number of modular part connected
Figure 5. Slave function: pin 4 (Ref to pin 8 -VS)
-VS +3V
-VS +1V
-VS
MASTER
UNDEFINED
SLAVE
D98AU821
Note:
If in the application, the speakers are connected via long wires, it is a good rule to add between the output
and GND, a Boucherot Cell, in order to avoid dangerous spurious oscillations when the speakers terminal
are shorted. The suggested Boucherot Resistor is 3.9Ω/2W and the capacitor is 1µF.
4
Introduction
In consumer electronics, an increasing demand has arisen for very high power monolithic audio amplifiers
able to match, with a low cost, the performance obtained from the best discrete designs.
The task of realizing this linear integrated circuit in conventional bipolar technology is made extremely difficult by the occurence of 2nd breakdown phoenomenon. It limits the safe operating area (SOA) of the power devices, and, as a consequence, the maximum attainable output power, especially in presence of highly
reactive loads. Moreover, full exploitation of the SOA translates into a substantial increase in circuit and
layout complexity due to the need of sophisticated protection circuits.
To overcome these substantial drawbacks, the use of power MOS devices, which are immune from secondary breakdown is highly desirable. The device described has therefore been developed in a mixed bipolar-MOS high voltage technology called BCDII 100.
4.1 Output Stage
The main design task in developping a power operational amplifier, independently of the technology used,
is that of realization of the output stage. The solution shown as a principle shematic by Fig.5 represents
the DMOS unity - gain output buffer of the TDA7294S.
6/16
TDA7294S
This large-signal, high-power buffer must be capable of handling extremely high current and voltage levels
while maintaining acceptably low harmonic distortion and good behaviour over frequency response; moreover, an accurate control of quiescent current is required.
A local linearizing feedback, provided by differential amplifier A, is used to fullfil the above requirements,
allowing a simple and effective quiescent current setting.
Proper biasing of the power output transistors alone is however not enough to guarantee the absence of
crossover distortion.
While a linearization of the DC transfer characteristic of the stage is obtained, the dynamic be-haviour of
the system must be taken into account. A significant aid in keeping the distortion contributed by the final
stage as low as possible is provided by the compensation scheme, which exploits the direct connection of
the Miller capacitor at the amplifier’s output to introduce a local AC feedback path enclosing the output
stage itself.
4.2 Protections
In designing a power IC, particular attention must be reserved to the circuits devoted to protection of the
device from short circuit or overload conditions. Due to the absence of the 2nd breakdown phenomenon,
the SOA of the power DMOS transistors is delimited only by a maximum dissipation curve dependent on
the duration of the applied stimulus.
In order to fully exploit the capabilities of the power transistors, the protection scheme implemented in this
device combines a conventional SOA protection circuit with a novel local temperature sensing technique
which " dynamically" controls the maximum dissipation.
Figure 6. Principle Schematic of a DMOS unity-gain buffer.
+VDD
I ref
M1
MR
Vo
+
-
A
M2
Vi
-VSS
7/16
TDA7294S
Figure 7. Turn ON/OFF Suggested Sequence
+Vs
(V)
+40
-40
-Vs
VIN
(mV)
VST-BY
PIN #9
(V)
VMUTE
PIN #10
(V)
5V
5V
IQ
(mA)
VOUT
(V)
OFF
ST-BY
PLAY
ST-BY
MUTE
OFF
MUTE
D98AU817
Figure 8. Single Signal ST-BY/MUTE Control Circuit
MUTE
MUTE/
ST-BY
STBY
20K
10K
30K
1N4148
10µF
10µF
D93AU014
8/16
TDA7294S
In addition to the overload protection described above, the device features a thermal shutdown circuit
which initially puts the device into a muting state (@ Tj = 150°C) and then into stand-by (@ Tj = 160°C).
Full protection against electrostatic discharges on every pin is included.
4.3 Other Features
The device is provided with both stand-by and mute functions, independently driven by two CMOS logic
compatible input pins.
The circuits dedicated to the switching on and off of the amplifier have been carefully optimized to avoid
any kind of uncontrolled audible transient at the output.
The sequence that we recommend during the ON/OFF transients is shown by Figure 7.
The application of figure 5 shows the possibility of using only one command for both st-by and mute functions. On both the pins, the maximum applicable range corresponds to the operating supply voltage.
5
Application Information
5.1 HIGH-EFFICIENCY
Constraints of implementing high power solutions are the power dissipation and the size of the power supply. These are both due to the low efficiency of conventional AB class amplifier approaches.
Here below (figure 9) is described a circuit proposal for a high efficiency amplifier which can be adopted
for both HI-FI and CAR-RADIO applications.
The TDA7294S is a monolithic MOS power amplifier which can be operated at 90V supply voltage (100V
with no signal applied) while delivering output currents up to ±6.5 A.
This allows the use of this device as a very high power amplifier (up to 100W as peak power with
T.H.D.=10 % and Rl = 4 Ohm); the only drawback is the power dissipation, hardly manageable in the
above power range.
The typical junction-to-case thermal resistance of the TDA7294S is 1 °C/W (max= 1.5 °C/W). To avoid
that, in worst case conditions, the chip temperature exceedes 150°C, the thermal resistance of the heatsink must be 0.038 °C/W (@ max ambient temperature of 50 °C).
As the above value is pratically unreachable; a high efficiency system is needed in those cases where the
continuous RMS output power is higher than 50-60 W.
The TDA7294S was designed to work also in higher efficiency way.
For this reason there are four power supply pins: two intended for the signal part and two for the power
part.
T1 and T2 are two power transistors that only operate when the output power reaches a certain threshold
(e.g. 20 W). If the output power increases, these transistors are switched on during the portion of the signal
where more output voltage swing is needed, thus "bootstrapping" the power supply pins (#13 and #15).
The current generators formed by T4, T7, zener diodes Z1, Z2 and resistors R7,R8 define the minimum
drop across the power MOS transistors of the TDA7294S. L1, L2, L3 and the snubbers C9, R1 and C10,
R2 stabilize the loops formed by the "bootstrap" circuits and the output stage of the TDA7294S.
By considering again a maximum average output power (music signal) of 20W, in case of the high efficiency application, the thermal resistance value needed from the heatsink is 2.2°C/W (Vs = ±45V and Rl=
8Ohm).
All components (TDA7294S and power transistors T1 and T2) can be placed on a 1.5°C/W heatsink, with
the power darlingtons electrically insulated from the heatsink.
Since the total power dissipation is less than that of a usual class AB amplifier, additional cost savings can
be obtained while optimizing the power supply, even with a high heatsink .
9/16
TDA7294S
5.2 BRIDGE APPLICATION
Another application suggestion is the BRIDGE configuration, where two TDA7294S are used. In this application, the value of the load must not be lower than 8Ohm for dissipation and current capability reasons.
A suitable field of application includes HI-FI/TV subwoofers realizations.
The main advantages offered by this solution are:
– High power performances with limited supply voltage level.
– Considerably high output power even with high load values (i.e. 16 Ohm).
With Rl= 8 Ohm, Vs = ±25V the maximum output power obtainable is 150W, while with Rl=16 Ohm, Vs =
±40V the maximum Pout is 200W (Music Power).
6
APPLICATION NOTE: (ref. fig. 10)
6.1 Modular Application (more Devices in Parallel)
The use of the modular application lets very high power be delivered to very low impedance loads. The
modular application implies one device to act as a master and the others as slaves.
The slave power stages are driven by the master device and work in parallel all together, while the input
and the gain stages of the slave device are disabled, the figure below shows the connections required to
configure two devices to work together.
■
■
■
■
■
■
The master chip connections are the same as the normal single ones.
The outputs can be connected together without the need of any ballast resistance.
The slave SGND pin must be tied to the negative supply.
The slave ST-BY pin must be connected to ST-BY pin.
The bootstrap lines must be connected together and the bootstrap capacitor must be increased: for N
devices the boostrap capacitor must be 22µF times N.
The slave Mute and IN-pins must be grounded.
6.2 THE BOOTSTRAP CAPACITOR
For compatibility purpose with the previous devices of the family, the boostrap capacitor can be connected
both between the bootstrap pin (6) and the output pin (14) or between the boostrap pin (6) and the bootstrap loader pin (12).
When the bootcap is connected between pin 6 and 14, the maximum supply voltage in presence of output
signal is limited to 80V, due the bootstrap capacitor overvoltage.
When the bootcap is connected between pins 6 and 12 the maximum supply voltage extend to the full
voltage that the technology can stand: 100V. This is accomplished by the clamp introduced at the bootstrap loader pin (12): this pin follows the output voltage up to 100V and remains clamped at 100V. This
feature lets the output voltage swing up to a gate-source voltage from the positive supply (VS -3 to 6V)
10/16
TDA7294S
Figure 9. High Efficiency Application Circuit
+50V
D6
1N4001
T1
BDX53A
T3
BC394
R4
270
D1 BYW98100
+25V
T4
BC393
R17 270
L1 1µH
D3 1N4148
C12 330nF
R20
20K
C1
1000µF
63V
C3
100nF
C5
1000µF
35V
C7
100nF
R22
10K
C9
330nF
IN
C2
1000µF
63V
7
13
2
C4
100nF
C6
1000µF
35V
R23
10K
C8
100nF
R2
2
C10
330nF
D5
1N4148
6
R13 20K
1
R15 10K
10
C14
10µF
D2 BYW98100
-25V
D7
1N4001
R6
20K
C11 22µF
R7
3.3K
L3 5µH
C16
1.8nF
OUT
14
C13 10µF
R14 30K
R3 680
R16
13K
9
ST-BY
R21
20K
3
4
PLAY
GND
T5
BC393
Z1 3.9V
R12
13K
R1
2
R5
270
R18 270
C15
22µF
R8
3.3K
12
8
C17
1.8nF
Pot
15
Z2 3.9V
L2 1µH
D4 1N4148
T7
BC394
R19 270
T2
BDX54A
T6
BC393
R9
270
T8
BC394
R10
270
R11
20K
-50V
D97AU807C
Figure 10. PCB and Component Layout of the fig. 9
11/16
TDA7294S
Figure 11. PCB and Component Layout of the fig. 9
Figure 12. Modular Application Circuit
+Vs
C7 100nF
C6 1000µF
R3 22K
MASTER
BUFFER
DRIVER
+Vs
C2
22µF
R2
680Ω
C1 470nF
IN-
2
IN+
3
+PWVs
11
7
13
-
R1 22K
VMUTE
R5 10K
SGND
4
MUTE
10
STBY
9
R4 22K
C4 10µF
OUT
12
BOOT
LOADER
6
MUTE
VSTBY
14
+
THERMAL
SHUTDOWN
STBY
S/C
PROTECTION
1
8
15
STBY-GND
-Vs
-PWVs
C9 100nF
C3 10µF
5
C10
100nF
R7
2Ω
C5
47µF
BOOTSTRAP
CLIP DET
C8 1000µF
-Vs
+Vs
C7 100nF
C6 1000µF
BUFFER
DRIVER
+Vs
IN-
2
IN+
3
7
+PWVs
13
11
-
4
MUTE
10
9
STBY
12
BOOT
LOADER
6
MUTE
THERMAL
SHUTDOWN
STBY
S/C
PROTECTION
1
8
15
STBY-GND
-Vs
-PWVs
C9 100nF
C8 1000µF
-Vs
12/16
OUT
+
SLAVE
SGND
14
5
BOOTSTRAP
D97AU808C
TDA7294S
Figure 13. Modular Application P.C. Board and Component Layout (Component SIDE)
Figure 14. Modular Application P.C. Board and Component Layout (Solder SIDE)
13/16
TDA7294S
7
Package Information
Figure 15. Multiwatt15 (Vertical) Mechanical Data & Package Dimensions
DIM.
mm
MIN.
TYP.
inch
MAX.
MIN.
TYP.
A5
MAX.
0.197
B
2.65
C
1.6
D
OUTLINE AND
MECHANICAL DATA
0.104
0.063
1
0.039
E
0.49
0.55
0.019
0.022
F
0.66
0.75
0.026
0.030
G
1.02
1.27
1.52
0.040
0.050
0.060
G1
17.53
17.78
18.03
0.690
0.700
0.710
H1
19.6
0.772
H2
20.2
0.795
L
21.9
22.2
22.5
0.862
0.874
0.886
L1
21.7
22.1
22.5
0.854
0.87
0.886
L2
17.65
18.1
0.695
L3
17.25
17.5
17.75
0.679
0.689
0.699
L4
10.3
10.7
10.9
0.406
0.421
0.429
0.191
0.713
L7
2.65
2.9
0.104
M
4.25
4.55
4.85
0.167
0.179
0.114
M1
4.73
5.08
5.43
0.186
0.200
S
1.9
2.6
0.075
0.102
S1
1.9
2.6
0.075
0.102
Dia1
3.65
3.85
0.144
0.152
0.214
Multiwatt15 (Vertical)
0016036 J
14/16
TDA7294S
8
Revision History
Table 7. Revision History
Date
Revision
Description of Changes
January 2003
1
First Issue in EDOCS (migrated from ST-Press DMS).
February 2005
2
Added “Clip Detector Electrical Characteristics” in the Table 5 (page 6).
15/16
TDA7294S
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to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not
authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics.
The ST logo is a registered trademark of STMicroelectronics.
All other names are the property of their respective owners
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