–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 V
load
■ Very inductive loads
■ Overrating chip temperature with soft thermal
limiter
■ Output DC offset detection
■ Load dump voltage
■ Fortuitous open gnd
■ Reversed battery
Table 1.Device summary
, across the
s
TDA7850A
Flexiwatt27
(vertical)
Flexiwatt27
(horizontal)
■ 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/NChannel 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.
Figure 5.Output power vs. supply voltage (R
Figure 6.Output power vs. supply voltage (R
Figure 7.Distortion vs. output power (R
Figure 8.Distortion vs. output power (R
Figure 9.Distortion vs. frequency (R
Figure 10.Distortion vs. frequency (R
Figure 14.Power dissipation and efficiency vs. output power (R
Figure 15.Power dissipation and efficiency vs. output power (R
Figure 16.Power dissipation vs. output power (R
Figure 17.Power dissipation vs. output power (R
Dropout voltageIO = 0.35 A; VS = 9 to 16 V0.250.6V
Current limits400800mA
prot
8/16
Page 9
TDA7850AElectrical specifications
Vs (V)
Po (W)
Vs (V)
RL= 4Ω
f = 1 KHz
Po-max
THD= 10%
THD= 1%
Vs (V)
Po (W)
Po-max
THD=10%
THD=1%
RL= 2Ω
f = 1 KHz
Po (W)
THD (%)
VS = 14.4 V
R
L
= 4Ω
f = 1 KHz
f = 10 KHz
Table 4.Electrical characteristics (continued)
(Refer to the test and application diagram, V
T
= 25 °C; unless otherwise specified).
amb
SymbolParameterTest conditionMin. Typ.Max.Unit
Offset detector (Pin 26)
= 14.4 V; RL = 4 Ω; Rg = 600 Ω; f = 1 kHz;
S
V
M_ON
V
M_OFF
V
V
V
Mute voltage for DC offset
detection enabled
Detected differential output offset V
OFF
Pin 26 voltage for detection =
26_T
TRUE
Pin 26 voltage for detection =
26_F
FALSE
V
V
V
V
V
ST-B
ST-B
ST-B
OFF
ST-B
OFF
= 5 V
Y
= 5 V; V
Y
= 5 V; V
Y
> ±4 V
= 5 V; V
Y
> ±2 V
mute
mute
mute
1. Saturated square wave output.
3.4 Electrical characteristic curves
Figure 4.Quiescent current vs. supply
voltage
Id (mA)
200
Vi = 0
190
RL =
180
170
160
150
140
130
120
110
100
∞
8 1012141618
Figure 5.Output power vs. supply voltage
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
AC00064
89101112131415161718
8V
6V
= 8 V±2±3±4V
= 8 V
= 8 V
(R
L
01.5V
12V
= 4 Ω)
AC00064
Figure 6.Output power vs. supply voltage
(R
= 2 Ω)
130
120
110
100
90
80
70
60
50
40
30
20
10
0
89101112131415161718
L
Figure 7.Distortion vs. output power
(R
= 4 Ω)
10
1
0.1
0.01
0.001
AC00066
0.1110100
9/16
L
AC00067
Page 10
Electrical specificationsTDA7850A
Po (W)
THD (%)
VS = 14.4 V
RL = 2Ω
f = 10 KHz
f = 1 KHz
f (Hz)
THD (%)
VS = 14.4 V
R
L
= 4Ω
P
o
= 4 W
f (Hz)
THD (%)
VS = 14.4 V
R
L
= 2Ω
P
o
= 8 W
R
L
= 4Ω
P
o
= 4 W
R
g
= 600Ω
f (Hz)
CROSSTALK (dB)
f (Hz)
SVR (dB)
Rg = 600Ω
Vripple = 1 Vrms
Vs (V)
OUTPUT ATTN (dB)
RL = 4Ω
P
o
= 4 W ref
Figure 8.Distortion vs. output power
(R
= 2 Ω)
10
1
0.1
0.01
0.001
0.1110100
L
Figure 10. Distortion vs. frequency
(R
= 2 Ω)
10
1
0.1
0.01
0.001
10100100010000100000
L
AC00068
AC00070
Figure 9.Distortion vs. frequency
(R
= 4 Ω)
10
1
0.1
0.01
0.001
10100100010000100000
L
Figure 11. Crosstalk vs. frequency
-20
-30
-40
-50
-60
-70
-80
-90
-100
10100100010000100000
AC00069
AC00071
Figure 12. Supply voltage rejection vs.
frequency
-20
-30
-40
-50
-60
-70
-80
-90
-100
10100100010000100000
10/16
AC00072
Figure 13. Output attenuation vs. supply
voltage
0
-20
-40
-60
-80
-100
5678910
AC00073
Page 11
TDA7850AElectrical specifications
P
tot
(W)
η
(%)
Po (W)
0
10
20
30
40
50
60
70
80
90
P
tot
η
VS = 14.4 V
R
L
= 4 x 4Ω
f = 1 KHz SINE
Ptot (W)
η
(%)
Po (W)
P
tot
η
VS = 14.4 V
R
L
= 4 x 2Ω
f = 1 KHz SINE
6
VS = 13.2 V
R
L
= 4 x 4Ω
GAUSSIAN NOISE
CLIP START
P
tot
(W)
Po (W)
VS = 13.2 V
R
L
= 4 x 2Ω
GAUSSIAN NOISE
CLIP START
P
tot
(W)
Po (W)
Figure 14. Power dissipation and efficiency
vs. output power (R
90
80
70
60
50
40
30
20
10
0
02468 10 12 14 16 18 20 22 24 26 28 30
= 4 Ω, SINE)
L
AC00074
Figure 16. Power dissipation vs. output power
(R
= 4Ω, audio program simulation)
30
25
20
15
10
5
0123456
L
AC0007
Figure 15. Power dissipation and efficiency
vs. output power (R
180
160
140
120
100
80
60
40
20
0
0510152025303540455055
= 2 Ω, SINE)
L
90
80
70
60
50
40
30
20
10
0
AC00075
Figure 17. Power dissipation vs. output power
(R
= 2Ω, audio program simulation)
60
55
50
45
40
35
30
25
20
15
10
5
0246810
L
AC00077
Figure 18. ITU R-ARM frequency response,
weighting filter for transient pop
Output attenuation (dB)
10
0
-10
-20
-30
-40
-50
10100100010000100000
Hz
AC00343
11/16
Page 12
Application hintsTDA7850A
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,
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
Its minimum recommended value is 10µF
.
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 P
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.
= 26W. Assuming T
diss
= 70°C and T
amb
= 150°C as boundary conditions, the
CHIP
12/16
Page 13
TDA7850APackage information
5 Package information
In order to meet environmental requirements, ST (also) offers these devices in ECOPACK®
packages. ECOPACK
®
packages are lead-free. The category of second Level Interconnect
is marked on the package and on the inner box label, in compliance with JEDEC Standard
JESD97. The maximum ratings related to soldering conditions are also marked on the inner
box label.
ECOPACK is an ST trademark. ECOPACK specifications are available at: www.st.com.
Figure 19. Flexiwatt27 (vertical) mechanical data and package dimensions
(1): dam-bar protusion not included; (2): molding protus ion included
mminch
MIN. TYP. MAX. MIN. TYP. MAX.
OUTLINE AND
MECHANICAL DATA
Flexiwatt27
(Horizontal)
14/16
7399738 A
Page 15
TDA7850ARevision history
6 Revision history
Table 5.Document revision history
DateRevisionChanges
09-Oct-20071Initial release.
12-Sep-20082Updated the values of VOS and THD parameters on the Ta bl e 4 .
07-Nov-20083
Modified max. values of the THD distortion in Table 4: Electrical
characteristics on page 8.
15/16
Page 16
TDA7850A
Please Read Carefully:
Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the
right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any
time, without notice.
All ST products are sold pursuant to ST’s terms and conditions of sale.
Purchasers are solely responsible for the choice, selection and use of the ST products and services described herein, and ST assumes no
liability whatsoever relating to the choice, selection or use of the ST products and services described herein.
No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. If any part of this
document refers to any third party products or services it shall not be deemed a license grant by ST for the use of such third party products
or services, or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoever of such
third party products or services or any intellectual property contained therein.
UNLESS OTHERWISE SET FORTH IN ST’S TERMS AND CONDITIONS OF SALE ST DISCLAIMS ANY EXPRESS OR IMPLIED
WARRANTY WITH RESPECT TO THE USE AND/OR SALE OF ST PRODUCTS INCLUDING WITHOUT LIMITATION IMPLIED
WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS
OF ANY JURISDICTION), OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT.
UNLESS EXPRESSLY APPROVED IN WRITING BY AN AUTHORIZED ST REPRESENTATIVE, ST PRODUCTS ARE NOT
RECOMMENDED, AUTHORIZED OR WARRANTED FOR USE IN MILITARY, AIR CRAFT, SPACE, LIFE SAVING, OR LIFE SUSTAINING
APPLICATIONS, NOR IN PRODUCTS OR SYSTEMS WHERE FAILURE OR MALFUNCTION MAY RESULT IN PERSONAL INJURY,
DEATH, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE. ST PRODUCTS WHICH ARE NOT SPECIFIED AS "AUTOMOTIVE
GRADE" MAY ONLY BE USED IN AUTOMOTIVE APPLICATIONS AT USER’S OWN RISK.
Resale of ST products with provisions different from the statements and/or technical features set forth in this document shall immediately void
any warranty granted by ST for the ST product or service described herein and shall not create or extend in any manner whatsoever, any
liability of ST.
ST and the ST logo are trademarks or registered trademarks of ST in various countries.
Information in this document supersedes and replaces all information previously supplied.
The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners.