TDA7296A
70V - 60W DMOS AUDIO AMPLIFIER WITH MUTE/ST-BY
PRODUCT PREVIEW
VERY HIGH OPERATING VOLTAGE RANGE
(±35V)
DMOS POWER STAGE
HIGH OUTPUT POWER (UP TO 60W MUSIC
POWER)
MUTI N G/STAND-BY FUNC TION S
NO SWITCH ON/OFF NOISE
NO BOU CHER OT CELLS
VERY LOW DISTORTION
VERY LOW NOISE
SHORT CIR C U IT PROTECTION
THERMA L SHUTDOW N
CLIPPIN G D ETE CTION OUTPUT
DESCRIPTION
The TDA7296A is a monolithic integrated circuit
in Multiwatt15 package, intended for use as audio
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 sup-
ply the highest power into both 4Ω and 8Ω loads
even in presence of poor supply regulation, with
high Supply Voltage Rejection.
The built in muting function with turn on delay
simplifies the remote operation avoiding switching
on-off noises.
The device provides a circuit for the detection of
clipping in the output stages. The output, on open
collector, is able to drive system with automatic
level control.
This is preliminary information on a new product now in development. Details are subject to change without notice.
June 1996
IN- 2
R2
680Ω
C2
22µF
C1 470nF IN+
R1 22K
3
R3 22K
-
+
MUTE
STBY
4
VM
VSTBY
10
9
IN+MUTE
MUTE
STBY
R4 22K
THERMAL
SHUTDOWN S/C
PROTECTION
R5 10K
C3 10µF C4 10µF
1
STBY-GND
C5
22µF
713
14
6
158
-Vs -PWVs
BOOTSTRAP
OUT
+PWVs+Vs
C9 100nF C8 1000µF
-Vs
D96AU494
+VsC7 100nF C6 1000µF
CD
5
+5V
Figure 1: Typical Application and Test Circuit
Multiwatt 15
ORDERING NUMBER: TDA7296AV
MULTIPOWER BCD TECHNOLOGY
1/13
+
+
-
+
-
+
CD
BOOTSTRAP
IN+
IN-
+VS
BOOTSTRAP
OUTPUT
CD
-VS
BIPOLAR
TRANSCONDUCTANCE
INPUT STAGE
MOS GAIN &
LEVEL SHIFTING
STAGE
MOS OUTPUT STAGE SHORT CIRCUIT
PROTECTION
D96AU496
BLOCK DIAGRAM
ABSOLUTE MAXIMUM RATINGS
Symbol Parameter Value Unit
VSSupply Voltage ±35 V
IOOutput Peak Current 5 A
Ptot Power Dissipation Tcase = 70°C50W
T
op Operating Ambient Temperature Range 0 to 70 °C
Tstg, TjStorage and Junction Temperature 150 °C
1
2
3
4
5
6
7
9
10
11
8
N.C.
MUTE
STAND-BY
-V
S
(SIGNAL)
+V
S
(SIGNAL)
BOOTSTRAP
CD
SVR
NON INVERTING INPUT
INVERTING INPUT
STAND-BY GND
13
14
15
12
-V
S
(POWER)
OUT
+V
S
(POWER)
N.C.
D96AU495
PIN C ONNECTION (Top view)
TDA7296A
2/13
THERMAL DATA
Symbol Description Value Unit
Rth j-case Thermal Resistance Junction-case Max 1.5 °C/W
ELECTRICA L CHARACTERI STICS (Refer to the Test Circuit VS = ±24V, RL = 8Ω, GV = 30dB;
Rg = 50 Ω; Tamb = 25°C , f = 1 kHz; unless otherwise specified.
Symbol Parameter Test Condition Min. Typ. Max. Unit
VSOperating Supply Range ±10 ±35 V
IqQuiescent Current 20 30 60 mA
IbInput Bias Current 500 nA
VOS Input Offset Voltage +10 mV
IOS Input Offset Current +100 nA
PORMS Continuous Output Power d = 0.5%:
VS = ± 24V, RL = 8Ω
VS = ± 21V, RL = 6Ω
ςS = ± 18V, RL = 4 Ω
27
27
27
30
30
30
W
W
W
Music Power (RMS) (*)
∆t = 1s d = 10%;
RL = 8Ω ; VS = ±29V
RL = 6Ω ; VS = ±24V
RL = 4Ω; VS = ±22V
60
60
60
W
W
W
d Total Harmonic Distortion (**) PO = 5W; f = 1kHz
PO = 0.1 to 20W; f = 20Hz to 20kHz 0.005 0.1 %
%
VS = ±18V, RL = 4Ω:
PO = 5W; f = 1kHz
PO = 0.1 to 20W; f = 20Hz to 20kHz 0.01 0.1 %
%
SR Slew Rate 7 10 V/µs
GVOpen Loop Voltage Gain 80 dB
GVClosed Loop Voltage Gain 24 30 40 dB
eNTotal Input Noise A = curve
f = 20Hz to 20kHz 1
25
µ
V
µ
V
f
L
, fHFrequency Response (-3dB) PO = 1W 20Hz to 20kHz
RiInput Resistance 100 kΩ
SVR Supply Voltage Rejection f = 100Hz; Vripple = 0.5Vrms 60 75 dB
TSThermal Shutdown 145 °C
STAND-BY FUNCTION (Ref: -VS or GND)
VST on Stand-by on Threshold 1.5 V
VST off Stand-by off Threshold 3.5 V
ATTst-by Stand-by Attenuation 70 90 dB
Iq st-by Quiescent Current @ Stand-by 1 3 mA
MUTE FUNCTION (Ref: -VS or GND)
VMon Mute on Threshold 1.5 V
VMoff Mute off Threshold 3.5 V
ATTmute Mute AttenuatIon 60 80 dB
DC Off Clipping detector OFF.
CD output Duty Cycle THD = 1% TBD %
DC On Clipping detector On.
CD output Duty Cycle THD = 10% TBD %
No te (* ):
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 i nput signal of frequ ency 1KHz .
No te (* *) : Tested with optimized Application Board (see fig. 2)
TDA7296A
3/13
Figure 2: P.C.B. and c omponents layout of the cir cuit of figure 1. (1:1 scale)
Note:
Th e Stand- by and Mute functions can be referred either to GND or -VS.
On the P.C.B. is possible to set both the configuration through the jum per J1.
TDA7296A
TDA7296A
4/13
APPLICATION SUGGES TION S (see Test and Application Circuits of the Fig. 1)
The rec ommended values of the external components ar e those s hown on t he application circuit of Fig-
ure 1. Different values can be used; the following table can help the designer.
COMPONENTS SUGGESTED VALUE PURPOSE LARGER THAN
SUGGESTED SMALLER THAN
SUGGESTED
R1 (*) 22k INPUT RESISTANCE INCREASE INPUT
IMPRDANCE DECREASE INPUT
IMPEDANCE
R2 680ΩCLOSED LOOP GAIN
SET TO 30dB (**) DECREASE OF GAIN INCREASE OF GAIN
R3 (*) 22k INCREASE OF GAIN DECREASE OF GAIN
R4 22k ST-BY TIME
CONSTANT LARGER ST-BY
ON/OFF TIME SMALLER ST-BY
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
C4 10µF ST-BY TIME
CONSTANT LARGER ST-BY
ON/OFF TIME SMALLER ST-BY
ON/OFF TIME;
POP NOISE
C5 22µF BOOTSTRAPPING SIGNAL
DEGRADATION AT
LOW FREQUENCY
C6, C8 1000µF SUPPLY VOLTAGE
BYPASS DANGER OF
OSCILLATION
C7, C9 0.1µF SUPPLY VOLTAGE
BYPASS DANGER OF
OSCILLATION
(*) R1 = R3 FO R POP OPTI MIZATI O N
(**) CLOSED LOOP GAIN HAS TO BE ≥ 24dB
TDA7296A
5/13
Figure 3: Output Power vs. Supply Voltage.
Figure 5: Output Power vs. Supply Voltage
Figure 4: Distortion vs. Output Power
Figure 8: Distortion vs. Frequency
TYPICAL CHARAC TERISTI CS
(Application Circuit of fig 1 unless otherwise specified)
Figure 6: Distortion vs. Output Power
Figure 7: Distortion vs. Frequency
TDA7296A
6/13
Figure 14: Power Dissipation vs. Output Power
Figure 13: Power Dis s ipation vs. Output P ower
Figure 11: Mute Attenuation vs. Vpin10 Figu re 12: St-by Attenuation vs. Vpin9
Figure 10: Supply Voltage Rejection vs. Frequency
TYPICAL CHARAC TERISTI CS (continued)
Figure 9: Quiescent Current vs. Supply Voltage
TDA7296A
7/13
INTRODUCTION
In consumer electronics, an increasing demand
has arisen for very high power monolithic audio
amplifiers able to match, with a low cost the per-
formance obtained from the best discrete de-
signs.
The task of realizing this linear integrated circuit
in conventional bipolar technology is made ex-
tremely difficult by the occurence of 2nd break-
down phenomenon. It limits the safe operating
area (SOA) of the power devices, and as a con-
sequence, the maximum attainable output power,
especially in presenc e of highly reactive loads.
Moreover, full exploitation of the SOA translates
into a substantial increase in circuit and layout
complexity due to the need for sophisticated pro-
tection circuits.
To overcome these substantial drawbacks, the
use of power MOS devices, which are immune
from secondar y breakdown is highly desirable.
The device described has therefore been devel-
oped in a mixed bipolar-MOS high voltage tech-
nology called BCD 80.
1) Output Stage
The main d esign task one is confronted with while
developing an integrated circuit as a power op-
erational amplifier, independently of the technol-
ogy used, is that of realis ing the output stage.
The solution shown as a principle schematic by
Fig 15 represents the DMOS unity-gain output
buffer of the TDA7296A.
This large-signal, high-power buffer must be ca-
pable of handling extrem ely high current and volt-
age levels while maintaining acceptably low har-
monic distortion and good behaviour over fre-
quency response; moreover, an accurate control
of quiescent current is required.
A local linearizing feedback, provided by differen-
tial amplifier A, is used to fullf il the above require-
ments, allowing a simple and effective quiescent
current setting.
Proper biasing of the power output transistors
alone is however not enough to guarantee the ab-
sence of crossover distortion.
While a linearization of the DC transfer charac-
teristic of the stage is obtained, the dynamic be-
haviour of the system must be taken into account.
A significant aid in keeping the distortion contrib-
uted by the final stage as low as possible is pro-
vided by the compensation scheme, which ex-
ploits the direct connection of the Miller capacitor
at the amplifier’s output to introduce a local AC
feedback path enclosing the output stage itself.
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 condi-
tions.
Due to the absence of the 2nd breakdown phe-
nomenon, the SOA of the power DMOS transis-
tors 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 imple-
mented in this device combines a conventional
SOA prot ect ion circuit with a novel local temper a-
ture sensing technique which " dynamically" con-
trols the maximum dissipation.
Figure 15: Principle Schematic of a DMOS unity-gain buffer.
TDA7296A
8/13
In addition to the overload protection described
above, the device features a thermal shutdown
circuit which initially puts the device into a mut ing
state (@ Tj = 145 oC) and then into stand-by (@
Tj = 150 oC).
Full protection against electrostatic dischar ges on
every pin is included.
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 t o the switching on and off
of the amplifier have been carefully optimized to
avoid any kind of unc ontrolled audible transient at
the output.
The sequence that we recommend during the
ON/OFF t ransient s is shown by Figure 16.
The application of figure 17 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.
1N4148
10K 30K
20K
10µF10µF
MUTE STBY
D93AU014
MUTE/
ST-BY
Figure 17: Single Signal ST-BY/MUTE Control
Circuit
PLAY
OFF
ST-BY
MUTE MUTE
ST-BY OFF
D93AU013
5V
5V
+Vs
(V)
+35
-35
VMUTE
PIN #10
(V)
VST-BY
PIN #9
(V)
-Vs
VIN
(mV)
IP
(mA)
VOUT
(V)
Figure 16: Turn ON/OFF Suggested Sequence
TDA7296A
9/13
BRIDGE APPLICATION
Another application suggestion is the BRIDGE
configuration, where two TDA7296A are used, as
shown by the schematic diagram of figure 19.
In this application, the value of the load must not
be lower than 8 Ohm for dissipation and current
capability reasons.
A suitable field of application includes HI-FI/TV
subwoofers realizations.
The main advant ages offered by this solution are:
- High power performances with limited s upply
volt age level.
- Considerably high output power even with high
load values (i.e. 16 Ohm).
The characteristics shown by figures 21 and 22,
measured with loads respectively 8 Ohm and 16
Ohm.
With Rl= 8 Ohm, Vs = ±18V the maxim um out put
power obtainable is 60W, while with Rl=16 Ohm,
Vs = ±24V the maximum Pout is 60W.
22K0.56µF
2200µF0.22µF
+
-
22µF
22K
680
22K
3
1
4
137
+Vs
Vi
815
2
14
6
10 9
+
-
3
0.56µF 22K
1
4
2
14
622µF
22K
680
10 9
22µF
15 8
-Vs
2200µF0.22µF
22µF
20K
10K 30K
1N4148
ST-BY/MUTE
137
D96AU497
Figure 19: Bridge Application Circuit
4) Clipping Detector Output
The TDA7296A is equipped with an internal cir-
cuit able to detect the output s tage saturation pro-
viding a proper current sinking into on open col-
lector out put (pin 5) when a c er tain distortion level
is reached at output.
This particular function allows gain compression
facility whenever the amplifier is overdriven, thus
obtaining high quality sound all list ening levels.
V
O
I
CLIP
OUTPUT
SIGNAL
t
S96AU498
Figure 18: Clipping Detector Output Waveform
TDA7296A
10/13
Figure 21: Distortion vs. Output Power
Figure 20: Frequency Response of the Bridge
Application
Figure 22: Distortion vs. Output Power
TDA7296A
11/13
DIM. mm inch
MIN. TYP. MAX. MIN. TYP. MAX.
A 5 0.197
B 2.65 0.104
C 1.6 0.063
D 1 0.039
E 0.49 0.55 0.019 0.022
F 0.66 0.75 0.026 0.030
G 1.14 1.27 1.4 0.045 0.050 0.055
G1 17.57 17.78 17.91 0.692 0.700 0.705
H1 19.6 0.772
H2 20.2 0.795
L 22.1 22.6 0.870 0.890
L1 22 22.5 0.866 0.886
L2 17.65 18.1 0.695 0.713
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
L7 2.65 2.9 0.104 0.114
M 4.2 4.3 4.6 0.165 0.169 0.181
M1 4.5 5.08 5.3 0.177 0.200 0.209
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
MULTIWATT15 PAC KAGE MECHANICAL DAT A
TDA7296A
12/13
Infor mation furni shed is believe d to be ac cur ate and reliabl e. Howev er, SGS-THOM SON M icroelect ronics as sumes no res pons ibility for th e
consequences of use of suc h i nf orm ation nor f or any i nfringem ent of patents or other ri ghts of thi rd part i es which may result f rom i ts use. No
license is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specification mentioned
in this p ublication are subj ect to c hange without notice. This public ation super sede s and replac es al l informa tion previ ously supplied. SGS-
THOMSON Mic roelectronics products are not author iz ed fo r use as critical component s in life su pport devices or systems without ex press
written approval of SGS-THOMSON Microelectronics.
© 1996 SGS-THOMSON Microelectronics – Printed in Italy – All Rights Reserved
SGS-THOMSON Microelectronics GROUP OF COMPANIES
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TDA7296A
13/13
