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TDA7576B
Dual bridge MOSFET power amplifier for 24 V systems
Datasheet  production data
Features
■
Multipower BCD technology
■
24 V battery operation
■
MOSFET output power stage
■
High output power capability
– 2 x 20 W/4  @ 24 V, 1 kHz; 10 %
■
Minimized external components
– No decoupling capacitors
– No bootstrap capacitor
– No external compensation
– Internally fixed gain
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Multiwatt15
■
Standby function
■
Mute function
■
Diagnostic pin for:
– clip detector (THD 2 %)
– short circuit detection
– thermal protection
■
Output DC offset detection
■
Protections:
– 60 V load dump
– Overrating chip temperature
– Out short circuit protection (to GND, Vcc
and across the load)
– ESD
Table 1.
Description
The TDA7576B is a dual bridge power amplifier
with MOSFET output power stages. It has been
specifically designed for 24 V power supply
systems making it compatible with truck/bus
applications.
The feedback topology allows excellent distortion
performances and the integrated buffer minimizes
the need for external components. The fully
complementary P-channel/N-channel output
structure allows rail-to-rail output voltage swing
minimizing saturation losses.
The TDA7576B integrates a DC offset detector, a
clipping detector and a diagnostic output.
Device summary
Order code
Package
Packing
TDA7576B
Multiwatt15
Tube
September 2013
This is information on a product in full production.
Doc ID 023511 Rev 3
1/17
www.st.com
1
Contents
TDA7576B
Contents
1
Block and application diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2
Pins description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3
Electrical specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1
Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.2
Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.3
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.4
Electrical characteristics curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4
Principle of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5
Power dissipation computation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6
Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6.1
Diagnostics pins description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6.2
Thermal protections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7
Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
8
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2/17
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TDA7576B
List of tables
List of tables
Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Pins information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Thermal data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
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List of figures
TDA7576B
List of figures
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.
Figure 11.
Figure 12.
Figure 13.
4/17
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Application diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Pins connection (top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Audio section waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Quiescent current vs. supply voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Output power vs. supply voltage (RL = 4 ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Distortion vs. output power (RL = 4 ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Crosstalk vs. frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Total power dissipation and efficiency vs. Po (RL = 4 ) . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Power dissipation vs. average Po (audio program simulation, 4 ) . . . . . . . . . . . . . . . . . . 10
Amplifier structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Thermal protection diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Multiwatt 15 (vertical) mechanical data and package dimensions . . . . . . . . . . . . . . . . . . . 15
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1
Block and application diagrams
Block and application diagrams
Figure 1.
Block diagram
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Application diagram
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Pins description
2
TDA7576B
Pins description
Figure 3.
Pins connection (top view)
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Table 2.
6/17
Pins information
Pin
number
Pin name
1
CD
Clip Detector
Open collector output
-0.3/VS
2
OD
Offset Detector
Open collector output
-0.3/VS
3
IN2
Left channel input
Input
-0.3/5 V
4
SVR
SVR
Output
-0.3/20 V
5
PGND2
Power ground 2
Ground
-0.3/0.3
6
OUT2
Left channel output
Output
N.A.
7
VCC2
Supply voltage 2
Supply
-0.3/VS
8
SGND
Signal ground
Ground
-0.3/0.3
9
HVCC
Half supply voltage buffer Output
10
PGND1
11
Description
Type
Max. applicable
voltage
N.A.
Power ground 1
Ground
-0.3/0.3
OUT1
Right channel output
Output
N.A.
12
VCC1
Supply voltage 1
Supply
-0.3/VS
13
STBY
STBY pin
Input
-0.3/VS
14
IN1
Right channel input
Input
-0.3/5 V
15
PM
Play/Mute pin
Input
-0.3/5 V
Doc ID 023511 Rev 3
TDA7576B
Electrical specification
3
Electrical specification
3.1
Absolute maximum ratings
Table 3.
Absolute maximum ratings
Symbol
Value
Unit
Operating supply voltage
32
V
VSPK
Peak supply voltage (t = 50 ms) not operating
60
V
VDCS
Not operating max. DC supply voltage
36
V
Ground pins
-0.3 to 0.3
V
VCC
Supply voltage
-0.3 to Vs
V
SVR
Supply voltage rejection filter
-0.3 to 20
V
IN1, IN2
Inputs
-0.3 to 5
V
OD, CD
Offset detector, clip detector pins
-0.3 to Vs
V
Play-mute pin
-0.3 to 5
V
85
W
-40 to 150
C
Value
Unit
2
°C/W
VS
PGND,
SGND
PM
Ptot
(1)
Tstg, Tj
Parameter
Power dissipation at Tcase = 85 °C
Storage and junction temperature range
1. Refer to Section 5 for detailed description of this value.
3.2
Thermal data
Table 4.
Thermal data
Symbol
Rth j-case
3.3
Parameter
Thermal resistance junction-to-case
Max.
Electrical characteristics
Refer to the test circuit; VS = 28 V; RL = 4 , Tamb = 25 °C, f = 1 kHz, Rg = 0, unless
otherwise specified.
Table 5.
Symbol
Electrical characteristics
Parameter
Test condition
Min.
Typ.
Max.
Unit
General
VS
Supply voltage
-
8
-
32
V
Iq
Total quiescent current
RL = 
-
90
130
mA
Standby current consumption
0 < VST_BY < 1.2 V
-
-
10
µA
Input impedance
-
50
55
-
k
IST-BY
RIN
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Electrical specification
Table 5.
TDA7576B
Electrical characteristics (continued)
Symbol
Parameter
Test condition
Min.
Typ.
Max.
Unit
VOS
Offset voltage
-
-100
-
+100
mV
Vdth
Dump threshold
-
36
37.5
39
V
Dump current
VS = 60 V
-
18
40
mA
THD = 1 %
20
22
-
THD = 10 %
25
28
-
Max. output power(1)
-
43
45
-
W
THD
Distortion
Po = 4 W; f = 1 kHz
-
0.05
0.1
%
CT
Cross talk
f = 1 kHz; Po = 4 W
f = 10 kHz; Po = 4 W
50
45
65
60
-
dB
dB
Gv
Voltage gain
25
26
27
dB
Amplifier in Mute
-
60
100
µV
ID
Audio section
Po
Po max.
Output power
voltage(2)
W
ENO
Output noise
SVR
Supply voltage rejection
f = 1 kHz; VR = 1 Vpk
-
50
-
dB
Standby input threshold voltage
-
-
-
1.2
V
Standby output threshold voltage
-
2.6
-
-
V
ASB
Standby attenuation
-
90
110
-
dB
IPIN
Standby pin current
Play mode
-1
-
1
µA
Mute attenuation
-
90
100
-
dB
Mute input threshold voltage
(Amp: Mute)
-
-
1.2
V
VM OUT
Mute output threshold voltage
(Amp: Play)
2.6
-
-
V
VAM in
VS automute threshold
Amp: play,
attenuation = -3 dB
Vout = 2 Vrms; f = 1 kHz
6.7
7.25
8
V
Standby
VSB IN
VSB OUT
Mute pin
AM
VM IN
Clipping detector(3)
CDTHD
Clipping detector THD level
10 V < Vs < 32 V
-
2
-
%
CDSAT
Clipping detector saturation
voltage
10 V < Vs < 32 V;
Cd; On; ICD = 1 mA
-
-
0.2
V
±1
±2
±3
V
-
-
0.2
V
Offset detector
OD
VOFF_SAT
Offset detector
Power amp. in play AC input = 0
Offset detector saturation voltage
Vo-Vhvcc > 3 V, IOD = 1 mA
1. Square wave input.
2. 22 Hz to 22 kHz.
3. Clip detector not guaranteed for Vs < 10 V.
8/17
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TDA7576B
Electrical specification
Figure 4.
Audio section waveforms
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3.4
Electrical characteristics curves
Figure 5.
Quiescent current vs. supply
voltage
Figure 6.
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Output power vs. supply voltage
(RL = 4 )
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Electrical specification
Figure 7.
TDA7576B
Distortion vs. output power
(RL = 4 )
Figure 8.
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Crosstalk vs. frequency
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Figure 9.
3R:
Total power dissipation and
efficiency vs. Po (RL = 4 )
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Figure 10. Power dissipation vs. average Po
(audio program simulation, 4 )
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Doc ID 023511 Rev 3
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TDA7576B
4
Principle of operation
Principle of operation
The TDA7576B is an innovative stereo audio amplifier meant for 24 V battery vehicles. The
amplifier works in a single-ended configuration without the large decoupling capacitors on
the outputs normally required by the s.e. topology. Its principle of operation is depicted in
Figure 11.
Figure 11. Amplifier structure
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Channel 1 is electrically inverting its input signal whereas channel 2 is not; if the speakers
are connected with the positive pole of speaker 2 connected to Out2 and the negative pole
of speaker 1 connected to Out1, then the two channels both behave as non-inverting.
Speaker 1 and speaker 2 have one terminal in common and further connected to a half Vcc
(HVCC) buffer.
If the signals at In1 and In2 are identical, then the voltage at Out1 and Out2 is identical in
magnitude but inverted (Out1 = -Out2), and the current flowing through speaker 1 is all
coming from speaker 2, with no current going into the HVCC buffer. If the signal at In1 is not
identical to that at In2, then the signal at the two outputs will not be identical either, and
some current will flow into or out of the HVCC buffer, keeping the voltage at HVCC constant.
This structure allows therefore the amplifier to operate in a single-ended configuration with
no need for decoupling capacitors.
Mathematically this can be expressed as:
VL1 = -G * Vin1
VL2 = +G * Vin2
IHVCC = Io1 + Io2 = VL1/RL + VL2/RL = G (Vin2 - Vin1) / RL
Doc ID 023511 Rev 3
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Principle of operation
TDA7576B
where VL1,2 is the voltage across speaker 1 or 2, G is the gain of the amplifiers and RL is the
load resistance (supposed identical for the two speakers).
In the common practice the two channels of the amplifier are used for the left and the right
audio parts of the stereo signal, and therefore the two outputs are not identical. This means
that it is never mathematically true that all the current into one speaker comes from the other
speaker, so the HVcc buffer will always have to provide a certain amount of difference
current.
Apart from the fact that the left and the right audio channels are not identical unless the
program is monophonic, other reasons why the HVcc buffer has to provide current are:
imbalance in the level of the L and the R channel, equalization-induced delay in one channel
compared to the other.
The current provided by the HVCC buffer leads to non-negligible power dissipation inside
the IC: this should be added to power dissipation the output stages 1 and 2. It is necessary
to keep this additional dissipation in mind when dimensioning the car-radio heat sink.
12/17
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TDA7576B
5
Power dissipation computation
Power dissipation computation
The instantaneous power dissipated by each output stage is given by the formula below:
PD1,2(t) = 1/RL |VL1,2(t)| (Vcc/2 - |VL1,2(t)|)
with VL1,2(t) being the output signal on each of the two channels (VL1,2(t) = G * Vin1,2(t)).
If the two input signals are not identical, as seen in Section 4 a current IHVcc flows into or
out of the half Vcc buffer; this current causes dissipation within the HVcc buffer given by:
PDHVCC(t) = Vcc/(2RL) | VL2(t) - VL1(t) |
which is obviously 0 when the two channels have identical signals.
The total instantaneous power dissipation inside the TDA7576B is therefore given by:
Pdtot(t) = PD1(t) + PD2(t) + PDHVCC(t).
The dimensioning of the heat sink of the system must take into consideration these three
components.
For more details on power dissipation and recommendations on heat-sink characteristics
computation, please refer to the complete application note related to this subject.
Doc ID 023511 Rev 3
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Functional description
TDA7576B
6
Functional description
6.1
Diagnostics pins description
TDA7576B includes an offset detector pin and a clip detector and diagnostic pin.
DC offset detector is intended to avoid that an anomalous DC offset on the inputs of the
amplifier may be multiplied by the gain and result in a dangerous large offset on the outputs.
This may lead to speakers damage due to overheating.
The feature works with the amplifier unmuted and no signal at the inputs.
Moreover there is a pin named CD/Diag: the behavior of this pin is showed on Figure 4.
Whenever a failure condition (between thermal warning, output waveform clipping, short
circuit to GND or VCC) is verified by the IC the level of this pin goes true (low).
6.2
Thermal protections
Thermal protection function is triggered when junction temperature rises above the normal
operating range, thus avoiding chip damaging.
For behavior description, refer to Figure 4 and 12. When temperature is reaching thermal
warning (Tw = typ 140 °C) the CD/Diag pin is driven low. Thermal foldback begins limiting
the audio input to the amplifier stage, this effectively limits the output power capability of the
device thus reducing the temperature to acceptable levels without totally interrupting the
operation of the device. Thermal mute is temperature when -6 dB output attenuation is
reached (typical Tm = 160 °C).
The output power will decrease to the point at which thermal equilibrium is reached.
Thermal equilibrium will be reached when the reduction in output power reduces the
dissipated power such that the die temperature falls below the thermal foldback threshold.
Figure 12. Thermal protection diagram
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TDA7576B
7
Package information
Package information
In order to meet environmental requirements, ST offers these devices in different grades of
ECOPACK® packages, depending on their level of environmental compliance. ECOPACK®
specifications, grade definitions and product status are available at: www.st.com.
ECOPACK® is an ST trademark.
Figure 13. Multiwatt 15 (vertical) mechanical data and package dimensions
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Doc ID 023511 Rev 3
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Revision history
8
TDA7576B
Revision history
Table 6.
16/17
Document revision history
Date
Revision
Changes
26-Sep-2012
1
Initial release.
05-Oct-2012
2
Updated Section 1: Block and application diagrams.
Updated Section 2: Pins description.
18-Sep-2013
3
Updated Disclaimer.
Doc ID 023511 Rev 3
TDA7576B
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