This is information on a product in full production.
August 2012 Doc ID 13998 Rev 4 1/16
1
TDA7850A
4 x 50 W MOSFET quad bridge power amplifier
Datasheet − production data
Features
■High output power capability:
–4 x 50 W/4 Ω max.
–4 x 30 W/4 Ω @ 14.4 V, 1 kHz, 10 %
–4 x 80 W/2 Ω max.
–4 x 55 W/2 Ω @ 14.4 V, 1 kHz, 10 %
■MOSFET output power stage
■Excellent 2 Ω 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
■On board 0.35 A high side driver
■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
– Fortuitous open gnd
– Reversed battery
–ESD
Description
The TDA7850A is a breakthrough MOSFET
technology class AB audio power amplifier in
Flexiwatt27 package designed for high power car
radio. The fully complementary P-Channel/N-
Channel output structure allows a rail to rail
output voltage swing which, combined with high
output current and minimized saturation losses
sets new power references in the car-radio field,
with unparalleled distortion performances.
The TDA7850A integrates a DC offset detector.
'!0'03
Flexiwatt27
(Horizontal)
Flexiwatt27
'!0'03
(VertIcal)
Table 1. Device summary
Order code Package Packing
TDA7850A Flexiwatt27 (vertical) Tube
TDA7850AH Flexiwatt27 (horizontal Tube
www.st.com
Contents TDA7850A
2/16 Doc ID 13998 Rev 4
Contents
1 Block diagram and application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2 Standard test and application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3 Electrical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.2 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.3 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.4 Electrical characteristic curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4 Application hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.1 SVR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.2 Input stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.3 Standby and muting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.4 DC offset detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.5 Heatsink definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5 Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
TDA7850A List of tables
Doc ID 13998 Rev 4 3/16
List of tables
Table 1. Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Table 2. Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Table 3. Thermal data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Table 4. Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Table 5. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
List of figures TDA7850A
4/16 Doc ID 13998 Rev 4
List of figures
Figure 1. Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 2. Standard test and application circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 3. Pin connections (top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 4. Quiescent current vs. supply voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 5. Output power vs. supply voltage (RL = 4 Ω) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 6. Output power vs. supply voltage (RL = 2 Ω) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 7. Distortion vs. output power (RL = 4 Ω) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 8. Distortion vs. output power (RL = 2 Ω) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 9. Distortion vs. frequency (RL = 4 Ω). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 10. Distortion vs. frequency (RL = 2 Ω). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 11. Crosstalk vs. frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 12. Supply voltage rejection vs. frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 13. Output attenuation vs. supply voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 14. Power dissipation and efficiency vs. output power (RL = 4 Ω, SINE) . . . . . . . . . . . . . . . . . 11
Figure 15. Power dissipation and efficiency vs. output power (RL = 2 Ω, SINE) . . . . . . . . . . . . . . . . . 11
Figure 16. Power dissipation vs. output power (RL = 4Ω, audio program simulation) . . . . . . . . . . . . . 11
Figure 17. Power dissipation vs. output power (RL = 2Ω, audio program simulation) . . . . . . . . . . . . . 11
Figure 18. ITU R-ARM frequency response, weighting filter for transient pop. . . . . . . . . . . . . . . . . . . 11
Figure 19. Flexiwatt27 (horizontal) mechanical data and package dimensions. . . . . . . . . . . . . . . . . . 13
Figure 20. Flexiwatt27 (vertical) mechanical data and package dimensions . . . . . . . . . . . . . . . . . . . . 14
TDA7850A Block diagram and application circuit
Doc ID 13998 Rev 4 5/16
1 Block diagram and application circuit
1.1 Block diagram
Figure 1. Block diagram
1.2 Standard test and application circuit
Figure 2. Standard test and application circuit
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Pin description TDA7850A
6/16 Doc ID 13998 Rev 4
2 Pin description
Figure 3. Pin connections (top view)
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TDA7850A Electrical specifications
Doc ID 13998 Rev 4 7/16
3 Electrical specifications
3.1 Absolute maximum ratings
3.2 Thermal data
3.3 Electrical characteristics
Refer to the test and application diagram, VS = 14.4 V; RL = 4 Ω; Rg = 600 Ω; f = 1 kHz;
Tamb = 25 °C; unless otherwise specified.
Table 2. Absolute maximum ratings
Symbol Parameter Value Unit
VSOperating supply voltage 18 V
VS (DC) DC supply voltage 28 V
VS (pk) Peak supply voltage (for t = 50 ms) 50 V
IO
Output peak current
repetitive (duty cycle 10 % at f = 10 Hz)
non repetitive (t = 100 μs)
9
10
A
A
Ptot Power dissipation Tcase = 70 °C 80 W
TjJunction temperature 150 °C
Tstg Storage temperature -55 to 150 °C
Table 3. Thermal data
Symbol Parameter Value Unit
Rth j-case Thermal resistance junction-to-case Max. 1 °C/W
Table 4. Electrical characteristics
Symbol Parameter Test condition Min. Typ. Max. Unit
I
q1
Quiescent current R
L
= ∞100 180 280 mA
V
OS
Output offset voltage Play mode - Mute mode - - ±50 mV
dV
OS
During mute ON/OFF output
offset voltage ITU R-ARM weighted
see Figure 18
-10 - +10 mV
During St-By ON/OFF output
offset voltage -10 - +10 mV
G
v
Voltage gain - 25 26 27 dB
dG
v
Channel gain unbalance - - - ±1 dB
Electrical specifications TDA7850A
8/16 Doc ID 13998 Rev 4
P
o
Output power
V
S
= 13.2 V; THD = 10 %
V
S
= 13.2 V; THD = 1 %
V
S
= 14.4 V; THD = 10 %
V
S
= 14.4 V; THD = 1 %
23
16
28
20
25
19
30
23
-W
V
S
= 14.4 V; THD = 10 %, 2 Ω50 55 W
P
o max.
Max. output power(1) V
S
= 14.4 V; R
L
= 4 Ω
V
S
= 14.4 V; R
L
= 2 Ω-50
85 -W
THD Distortion P
o
= 4 W
P
o
= 15 W; R
L
= 2 Ω-0.006
0.015
0.02
0.03 %
e
No
Output noise "A" Weighted
Bw = 20 Hz to 20 kHz -35
50
50
70 μV
SVR Supply voltage rejection f = 100 Hz; V
r
= 1 Vrms 50 75 - dB
f
ch
High cut-off frequency P
O
= 0.5 W 100 300 - KHz
R
i
Input impedance 80 100 120 KΩ
C
T
Cross talk f = 1 kHz; P
O
= 4 W
f = 10 kHz; P
O
= 4 W
60
-
70
60
-
-dB
I
SB
Standby current consumption V
ST-B
Y = 1.5 V - - 20
μA
V
ST-B
Y = 0V - - 10
I
pin5
Standby pin current V
ST-BY
= 1.5V to 3.5V - - ±1 μA
V
SB out
Standby out threshold voltage (Amp: ON) 2.75 - - V
V
SB in
Standby in threshold voltage (Amp: OFF) - - 1.5 V
A
M
Mute attenuation P
Oref
= 4W 80 90 - dB
V
M out
Mute out threshold voltage (Amp: Play) 3.5 - - V
V
M in
Mute in threshold voltage (Amp: Mute) - - 1.5 V
V
AM in
VS automute threshold
(Amp: Mute)
Att ≥ 80 dB; P
Oref
= 4 W
(Amp: Play)
Att < 0.1 dB; P
O
= 0.5 W
6.5 7
7.5 8
V
I
pin23
Muting pin current
V
MUTE
= 1.5 V
(Sourced Current) 71218μA
V
MUTE
= 3.5 V -5 - 18 μA
HSD section
V
dropout
Dropout voltage I
O
= 0.35 A; V
S
= 9 to 16 V - 0.25 0.6 V
I
prot
Current limits - 400 - 800 mA
Table 4. Electrical characteristics (continued)
Symbol Parameter Test condition Min. Typ. Max. Unit
TDA7850A Electrical specifications
Doc ID 13998 Rev 4 9/16
3.4 Electrical characteristic curves
Offset detector (Pin 26)
V
M_ON
Mute voltage for DC offset
detection enabled V
ST-B
Y = 5 V 8--V
V
M_OFF
--6V
V
OFF
Detected differential output offset V
ST-B
Y = 5 V; V
mute
= 8 V ±2 ±3 ±4 V
V
26_T
Pin 26 voltage for detection =
TRUE
V
ST-B
Y = 5 V; V
mute
= 8 V
V
OFF
> ±4 V 0-1.5V
V
26_F
Pin 26 voltage for detection =
FALSE
V
ST-B
Y = 5 V; V
mute
= 8 V
V
OFF
> ±2 V 12 - - V
1. Saturated square wave output.
Figure 4. Quiescent current vs. supply
voltage
Figure 5. Output power vs. supply voltage
(RL = 4 Ω)
Figure 6. Output power vs. supply voltage
(RL = 2 Ω)
Figure 7. Distortion vs. output power
(RL = 4 Ω)
Table 4. Electrical characteristics (continued)
Symbol Parameter Test condition Min. Typ. Max. Unit
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Electrical specifications TDA7850A
10/16 Doc ID 13998 Rev 4
Figure 8. Distortion vs. output power
(RL = 2 Ω)
Figure 9. Distortion vs. frequency
(RL = 4 Ω)
Figure 10. Distortion vs. frequency
(RL = 2 Ω)
Figure 11. Crosstalk vs. frequency
Figure 12. Supply voltage rejection vs.
frequency
Figure 13. Output attenuation vs. supply
voltage
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TDA7850A Electrical specifications
Doc ID 13998 Rev 4 11/16
Figure 14. Power dissipation and efficiency
vs. output power (RL = 4 Ω, SINE)
Figure 15. Power dissipation and efficiency
vs. output power (RL = 2 Ω, SINE)
Figure 16. Power dissipation vs. output power
(RL = 4Ω, audio program simulation)
Figure 17. Power dissipation vs. output power
(RL = 2Ω, audio program simulation)
Figure 18. ITU R-ARM frequency response,
weighting filter for transient pop
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Application hints TDA7850A
12/16 Doc ID 13998 Rev 4
4 Application hints
Ref. to the circuit of Figure 2.
4.1 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 10µF
.
4.2 Input stage
The TDA7850A's inputs are ground-compatible and can stand very high input signals
(± 8Vpk) without any performance degradation.
If the standard value for the input capacitors (0.1µF) is adopted, the low frequency cut-off
will amount to 16 Hz.
4.3 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
470kΩ equivalent resistance should be present between the power supply and the muting
and stand-by pins.
R-C cells have always to be used in order to smooth down the transitions for preventing any
audible transient noises.
About the stand-by, the time constant to be assigned in order to obtain a virtually pop-free
transition has to be slower than 2.5V/ms.
4.4 DC offset detector
The TDA7850A 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.
The DC offset detection can be available at 2 different pins:
– Pin 2 (always enabled)
– Pin 26. Only enabled if Vmute (pin23) is set higher than 8V. If not (Vmute < 6 V)
pin 26 will revert to the original HSD function.
4.5 Heatsink definition
Under normal usage (4 Ohm 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) will
cause Pdiss = 26W. 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.
TDA7850A Package information
Doc ID 13998 Rev 4 13/16
5 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 (horizontal) mechanical data and package dimensions
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Package information TDA7850A
14/16 Doc ID 13998 Rev 4
Figure 20. Flexiwatt27 (vertical) mechanical data and package dimensions
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TDA7850A Revision history
Doc ID 13998 Rev 4 15/16
6 Revision history
Table 5. Document revision history
Date Revision Changes
09-Oct-2007 1Initial release.
12-Sep-2008 2Updated the values of VOS and THD parameters on the Ta bl e 4 .
07-Nov-2008 3Modified max. values of the THD distortion in Table 4: Electrical
characteristics on page 8.
14-Aug-2012 4Updated Section 5: Package information.
TDA7850A
16/16 Doc ID 13998 Rev 4
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