TDA7851A
4 x 48 W MOSFET quad bridge power amplifier
Datasheet production data
Features
■
Multipower BCD technology
■
High output power capability:
– 4 x 48 W/4 Max.
– 4 x 28 W/4 @ 14.4 V, 1 kHz, 10 %
– 4 x 72 W/2 Max.
■
MOSFET output power stage
■
Excellent 2 driving capability
■
Hi-Fi class distortion
■
Low output noise
■
Standby function
■
Mute function
■
Automute at min. supply voltage detection
■
Low external component count:
– Internally fixed gain (26 dB)
– No external compensation
– No bootstrap capacitors
'!0'03
■
Flexiwatt 27
– Fortuitous open GND
– Reversed battery
– ESD
Description
Protections:
– Output short circuit to GND, to Vs, across
the load
– Very inductive loads
– Overrating chip temperature with soft
thermal limiter
– Output DC offset detection
– Load dump voltage
Table 1.
The TDA7851A is a breakthrough MOSFET
technology class AB audio power amplifier,
designed for high-power car radio.
The fully complementary P-Channel/N-Channel
output structure allows a rail-to-rail output voltage
swing. This, combined with high output current
and minimized saturation losses, sets new power
references in the car-radio field, with unparalleled
distortion performance.
Device summary
Order code
Package
Packing
TDA7851A
Flexiwatt 27
Tube
September 2013
This is information on a product in full production.
Doc ID 17715 Rev 3
1/15
www.st.com
1
Contents
TDA7851A
Contents
1
2
3
4
Block diagram and application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2
Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1
Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2
Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Electrical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1
Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.2
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.3
Electrical characteristics curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Application hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.1
DC offset detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.2
SVR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.3
Input stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.4
Standby and muting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.5
Heatsink definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5
Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2/15
Doc ID 17715 Rev 3
TDA7851A
List of tables
List of tables
Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Thermal data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Doc ID 17715 Rev 3
3/15
List of figures
TDA7851A
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.
Figure 14.
Figure 15.
Figure 16.
Figure 17.
Figure 18.
Figure 19.
4/15
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Pin connection (top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Quiescent current vs. supply voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Output power vs. supply voltage (RL = 4 ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Output power vs. supply voltage (RL = 2 ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Distortion vs. output power (RL = 4 ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Distortion vs. output power (RL = 2 ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Distortion vs. frequency (RL = 4 ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Distortion vs. frequency (RL = 2 ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Crosstalk vs. frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Supply voltage rejection vs. frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Output attenuation vs. supply voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Power dissipation and efficiency vs. output power (RL = 4 , SINE) . . . . . . . . . . . . . . . . . 10
Power dissipation and efficiency vs. output power (RL = 2 , SINE) . . . . . . . . . . . . . . . . . 10
Power dissipation vs. output power (RL = 4 , audio program simulation) . . . . . . . . . . . . 11
Power dissipation vs. output power (RL = 2 , audio program simulation) . . . . . . . . . . . . 11
ITU R-ARM frequency response, weighting filter for transient pop. . . . . . . . . . . . . . . . . . . 11
Flexiwatt27 mechanical data and package dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Doc ID 17715 Rev 3
TDA7851A
Block diagram and application circuit
1
Block diagram and application circuit
1.1
Block diagram
Figure 1.
Block diagram
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6CC
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1.2
Application circuit
Figure 2.
Application circuit
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6
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Doc ID 17715 Rev 3
'!0'03
5/15
Pin description
TDA7851A
2
Pin description
2.1
Pin connection
Pin connection (top view)
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Thermal data
Table 2.
Symbol
Rth j-case
6/15
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2.2
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Figure 3.
Thermal data
Parameter
Thermal resistance junction-to-case
Doc ID 17715 Rev 3
Max
Value
Unit
1
°C/W
TDA7851A
Electrical specifications
3
Electrical specifications
3.1
Absolute maximum ratings
Table 3.
Absolute maximum ratings
Symbol
Parameter
Value
Unit
Operating supply voltage
18
V
VS (DC)
DC supply voltage
28
V
VS (pk)
Peak supply voltage (for t = 50 ms)
50
V
Output peak current
Non repetitive (t = 100 µs)
Repetitive (duty cycle 10 % at f = 10 Hz)
10
9
A
A
Power dissipation Tcase = 70 °C
85
W
Tj
Junction temperature
150
°C
Tstg
Storage temperature
-55 to 150
°C
VS
IO
Ptot
3.2
Electrical characteristics
Refer to the test and application diagram, VS = 14.4 V; RL = 4 ; Rg = 600 ; f = 1 kHz;
Tamb = 25 °C; unless otherwise specified.
Table 4.
Electrical characteristics
Symbol
Parameter
Test condition
Min.
Typ.
Max.
Unit
8
-
18
V
VS
Supply voltage range
-
Iq1
Quiescent current
RL =
100
150
300
mA
VOS
Output offset voltage
Play mode / Mute mode
-60
-
+60
mV
-10
-
+10
mV
dVOS
During mute ON/OFF output offset
voltage
ITU R-ARM weighted
see Figure 18
During standby ON/OFF output
offset voltage
-10
-
+10
mV
Gv
Voltage gain
-
25
26
27
dB
dGv
Channel gain unbalance
-
-
-
±1
dB
25
28
22
-
W
W
Po
Po max.
THD
Output power
VS = 14.4 V; THD = 10 %
VS = 14.4 V; THD = 1 %
VS = 14.4 V; THD = 10 %, 2
VS = 14.4 V; THD = 1 %, 2
-
48
38
-
W
W
Max. output power(1)
VS = 14.4 V; RL = 4
VS = 14.4 V; RL = 2
VS = 15.2 V; RL = 4
-
45
75
48
-
W
W
W
Distortion
Po = 4 W
-
0.01
0.05
%
Doc ID 17715 Rev 3
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Electrical specifications
Table 4.
TDA7851A
Electrical characteristics (continued)
Symbol
Parameter
Test condition
Min.
Typ.
Max.
Unit
-
35
50
100
µV
µV
eNo
Output noise
"A" Weighted
Bw = 20 Hz to 20 kHz
SVR
Supply voltage rejection
f = 100 Hz; Vr = 1 Vrms
50
70
-
dB
fch
High cut-off frequency
PO = 0.5 W
100
300
-
kHz
Ri
Input impedance
-
70
100
130
k
CT
Cross talk
f = 1 kHz, PO = 4 W
f = 10 kHz, PO = 4 W
60
70
60
-
dB
dB
-
20
µA
Standby current consumption
VSt-by = 1.2 V
-
ISB
VSt-by = 0
-
-
10
µA
Ipin5
Standby pin current
VSt-by = 1.2 V to 2.6 V
-
-
±1
µA
VSB out
Standby out threshold voltage
(Amp: ON)
2.6
-
-
V
VSB in
Standby in threshold voltage
(Amp: OFF)
-
-
1.2
V
Mute attenuation
POref = 4 W
80
90
-
dB
VM out
Mute out threshold voltage
(Amp: Play)
2.6
-
-
V
VM in
Mute in threshold voltage
(Amp: Mute)
-
-
1.2
V
(Amp: Mute)
Att 80 dB; POref = 4 W
6.7
7
(Amp: Play)
Att < 0.1 dB; PO = 0.5 W
-
7.5
8
V
VMUTE = 1.2 V
(Sourced current)
7
12
18
µA
VMUTE = 2.6 V
-5
-
18
µA
VSt-by = 5 V
±1
±2
±3
V
AM
VAM in
Ipin23
V
VS automute threshold
Muting pin current
Offset detector
VOFF
Detected differential output offset
VOFF_SAT Off detector saturation voltage
Vo > ±3 V, Ioff Det = 1 mA
0 V < Voff Det < 18 V
-
0.2
0.4
V
VOFF_LK
Vo < ±1 V
-
0
15
µA
Off detector leakage current
Clipping detector
CDLK
Clip detector high leakage current
Cd off
-
0
1
µA
CDSAT
Clip detector saturation voltage
DC On; ICD = 1 mA
-
0.2
0.4
V
CDTHD
Clip detector THD level
-
-
2
-
%
1. Saturated square wave output
8/15
Doc ID 17715 Rev 3
TDA7851A
Electrical specifications
3.3
Electrical characteristics curves
Figure 4.
Quiescent current vs. supply
voltage
Figure 5.
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6I
2,c
6S6
Figure 6.
Output power vs. supply voltage
(RL = 4 )
0O
MAX
2 , 7
F+(Z
4($
4($
Output power vs. supply voltage
(RL = 2 )
6S6
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Figure 7.
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Distortion vs. output power
(RL = 4 )
4($
0O
MAX
2,7
F+(Z
636
2,7
FK(Z
4($
FK(Z
4($
6S6
Figure 8.
Distortion vs. output power
(RL = 2 )
Figure 9.
4($
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Distortion vs. frequency
(RL = 4 )
4($
6S6
2,7
0O7
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6S6
2,7
0O7
F+(Z
F+(Z
0O7
F(Z
'!0'03
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'!0'03
9/15
Electrical specifications
TDA7851A
Figure 10. Distortion vs. frequency
(RL = 2 )
Figure 11. Crosstalk vs. frequency
4($
6S 6
2,7
0O 7
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2,7
0O7
2G7
F(Z
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Figure 12. Supply voltage rejection vs.
frequency
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Figure 13. Output attenuation vs. supply
voltage
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F(Z
2,7
0O7REF
F(Z
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H
6S6
2,X7
F+(Z3).%
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Figure 15. Power dissipation and efficiency vs.
output power (RL = 2 , SINE)
H
6S6
'!0'03
Figure 14. Power dissipation and efficiency
vs. output power (RL = 4 , SINE)
H
0TOT7
6S6
2,X7
F+(Z3).%
H
0TOT
0O7
10/15
0TOT
'!0'03
Doc ID 17715 Rev 3
0O7
'!0'03
TDA7851A
Electrical specifications
Figure 16. Power dissipation vs. output power Figure 17. Power dissipation vs. output power
(RL = 4 , audio program simulation)
(RL = 2 , audio program simulation)
0TOT7
6S6
2,X7
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0TOT7
6S6
2,X7
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0O7
'!0'03
0O7
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Figure 18. ITU R-ARM frequency response,
weighting filter for transient pop
/UTPUTATTENUATIOND"
(Z
'!0'03
Doc ID 17715 Rev 3
11/15
Application hints
4
Application hints
4.1
DC offset detector
TDA7851A
The TDA7851A integrates a DC offset detector 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 which may lead to speakers damage for overheating.
The feature works with the amplifier unmuted and no signal at the inputs.
4.2
SVR
Besides its contribution to the ripple rejection, the SVR capacitor governs the turn ON/OFF
time sequence and, consequently, plays an essential role in the pop optimization during
ON/OFF transients. To conveniently serve both needs, its minimum recommended value
is 10 µF.
4.3
Input stage
The TDA7851A's inputs are ground-compatible and can stand very high input signals
(± 8 Vpk) without any performance degradation.
If the standard value for the input capacitors (0.1µF) is adopted, the low frequency cut-off
amounts to 16 Hz.
The input capacitors should be 1/4 of the capacitor connected to AC-GND pin for optimum
pop performance.
4.4
Standby and muting
Standby and muting facilities are both CMOS-compatible. In absence of true CMOS ports or
microprocessors, a direct connection to Vs of these two pins is admissible but a 470 k
equivalent resistance should present between the power supply and the muting and standby pins.
R-C cells have always to be used in order to smooth down the transitions for preventing any
audible transient noises.
About the standby, the time constant to be assigned in order to obtain a virtually pop-free
transition has to be slower than 2.5 V/ms.
4.5
Heatsink definition
Under normal usage (4 speakers) the heatsink's thermal requirements have to be
deduced from Figure 16, which reports the simulated power dissipation when real
music/speech programmes are played out. Noise with gaussian-distributed amplitude was
employed for this simulation. Based on that, frequent clipping occurrence (worst-case)
causes Pdiss = 26 W. Assuming Tamb = 70° C and TCHIP = 150 °C as boundary conditions,
the heatsink's thermal resistance should be approximately 2 °C/W. This would avoid any
thermal shutdown occurrence even after long-term and full-volume operation.
12/15
Doc ID 17715 Rev 3
TDA7851A
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 19. Flexiwatt27 mechanical data and package dimensions
',0
0,1
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(
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*
*
+
+
+
+
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/
/
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2
5
5
5
5
5
9
9
9
9
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