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TDA7850
4 x 50W MOSFET
Quad bridge power amplifier plus HSD

Features
■ Superior output power capability:
4 x 50W/4Ω Max.
4 x 30W/4Ω @ 14.4V, 1KHz, 10%
4 x 80W/2Ω Max.
4 x 55W/2Ω @ 14.4V, 1KHz, 10%
■ MOSFET Output power stage
Flexiwatt25
■ Excellent 2Ω driving capability
(Vertical)
■ HI-FI class distortion
■ Low output noise
■ ST-BY Function
■ Mute function
■ Automute at min. supply voltage detection
■ Low external component count:
– Internally fixed gain (26dB) Flexiwatt25
– No external compensation (Horizontal)
– No bootstrap capacitors
■ On board 0.35A high side driver

Protections:
Description
■ Output short circuit to GND, to Vs, across the
load The TDA7850 is a breakthrough MOSFET
■ Very inductive loads technology class AB audio power amplifier in
Flexiwatt 25 package designed for high power car
■ Overrating chip temperature with soft thermal radio. The fully complementary P-Channel/N-
limiter Channel output structure allows a rail to rail
■ Output DC offset detection output voltage swing, which, combined with high
■ Load dump voltage output current and minimised saturation losses,
sets new power references in the car-radio field,
■ Fortuitous open GND with unparalleled distortion performances.
■ Reversed battery
The TDA7850 integrates a DC offset detector.
■ ESD

Order codes
Part number Package Packing
TDA7850 Flexiwatt25 (Vertical) Tube
TDA7850H Flexiwatt25 (Horizontal) Tube

November 2006 Rev 1 1/14

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Contents TDA7850

Contents

1 Block diagram and pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2 Electrical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3 Application hints (ref. to the circuit of Figure 3) . . . . . . . . . . . . . . . . . 10

3.1 SVR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2 Input stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.3 Stand-by and muting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.4 DC offset detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.5 Heatsink definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

4 Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

5 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

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TDA7850 List of tables

List of tables

Table 1. Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Table 2. Thermal data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Table 3. Electrical characteristcs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Table 4. Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

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List of figures TDA7850

List of figures

Figure 1. Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Figure 2. Pin connection (Top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 3. Standard test and application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 4. P.C.B. and component layout of the Figure 3.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 5. Flexiwatt25 (vertical) mechanical data & package dimensions. . . . . . . . . . . . . . . . . . . . . . 11
Figure 6. Flexiwatt25 (horizontal) mechanical data & package dimensions . . . . . . . . . . . . . . . . . . . 12

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TDA7850 Block diagram and pin description

1 Block diagram and pin description

Figure 1. Block diagram

Vcc1 Vcc2
470μF 100nF

ST-BY

MUTE HSD HSD/VOFF_DET

OUT1+
IN1 OUT1-
0.1μF PW-GND

OUT2+
IN2 OUT2-
0.1μF PW-GND

OUT3+
IN3 OUT3-
0.1μF PW-GND

OUT4+
IN4 OUT4-
0.1μF PW-GND

AC-GND SVR TAB S-GND

0.47μF 47μF
D94AU158D

Figure 2. Pin connection (Top view)

TAB 1 TAB 1
P-GND2 P-GND2
OUT2- OUT2-
ST-BY ST-BY
OUT2+ OUT2+
VCC VCC
OUT1- OUT1-
P-GND1 P-GND1
OUT1+ OUT1+
SVR SVR
IN1 IN1
IN2 IN2
S-GND S-GND
IN4 IN4
IN3 IN3
AC-GND AC-GND
OUT3+ OUT3+
P-GND3 P-GND3
OUT3- OUT3-
VCC VCC
OUT4+ OUT4+
MUTE MUTE
OUT4- OUT4-
P-GND4 P-GND4
HSD 25 HSD 25

D94AU159A D06AU1655

Vertical Horizontal

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Electrical specifications TDA7850

2 Electrical specifications

Table 1. Absolute maximum ratings

Symbol Parameter Value Unit

VCC Operating supply voltage 18 V

VCC (DC) DC Supply voltage 28 V
VCC (pk) Peak supply voltage (for t = 50ms) 50 V

Output peak current

IO repetitive (duty cycle 10% at f = 10Hz) 9 A
non repetitive (t = 100μs) 10 A
Ptot Power dissipation Tcase = 70°C 80 W
Tj Junction temperature 150 °C
Tstg Storage temperature -55 to 150 °C

Table 2. Thermal data

Symbol Parameter Value Unit

Rth j-case Thermal resistance junction to case Max. 1 °C/W

Table 3. Electrical characteristcs

(Refer to the test and application diagram, VS = 13.2V; RL = 4Ω; Rg = 600Ω; f = 1KHz; Tamb =
25°C; unless otherwise specified).
Symbol Parameter Test condition Min. Typ. Max. Unit

Iq1 Quiescent current RL = ∞ 100 180 280 mA

VOS Output offset voltage Play Mode ±60 mV
During mute ON/OFF output offset
±60 mV
voltage
dVOS
During St-By ON/OFF output offset
±60 mV
voltage
Gv Voltage gain 25 26 27 dB
dGv Channel gain unbalance ±1 dB
VS = 13.2V; THD = 10% 23 25 W
VS = 13.2V; THD = 1% 16 19 W
VS = 14.4V; THD = 10% 28 30 W
VS = 14.4V; THD = 1% 20 23 W
Po Output power
VS = 13.2V; THD = 10%, 2Ω 42 45 W
VS = 13.2V; THD = 1%, 2Ω 32 34 W
VS = 14.4V; THD = 10%, 2Ω 50 55 W
VS = 14.4V; THD = 1%, 2Ω 40 43 W
VS = 14.4V; RL = 4Ω 50 W
Po max. Max. output power (1)
VS = 14.4V; RL = 2Ω 80 W

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TDA7850 Electrical specifications

Table 3. Electrical characteristcs (continued)

(Refer to the test and application diagram, VS = 13.2V; RL = 4Ω; Rg = 600Ω; f = 1KHz; Tamb =
25°C; unless otherwise specified).
Symbol Parameter Test condition Min. Typ. Max. Unit

Po = 4W 0.006 0.05 %
THD Distortion
Po = 15W; RL = 2Ω 0.015 0.07 %
"A" Weighted 35 50 μV
eNo Output noise
Bw = 20Hz to 20KHz 50 70 μV
SVR Supply voltage rejection f = 100Hz; Vr = 1Vrms 50 70 dB
fch High cut-off frequency PO = 0.5W 100 300 KHz
Ri Input impedance 80 100 120 KΩ
f = 1KHz PO = 4W 70 - dB
CT Cross talk 60
f = 10KHz PO = 4W 60 - dB
VSt-By = 1.5V 20 μA
ISB St-By Current consumption
VSt-By = 0 10 μA
Ipin5 St-by pin current VSt-By = 1.5V to 3.5V ±10 μA
VSB out St-By Out threshold voltage (Amp: ON) 3.5 V
VSB in St-By in threshold voltage (Amp: OFF) 1.5 V
AM Mute attenuation POref = 4W 80 90 dB
VM out Mute out threshold voltage (Amp: Play) 3.5 V
VM in Mute in threshold voltage (Amp: Mute) 1.5 V
(Amp: Mute)
Att ≥ 80dB; POref = 4W 7 V
VAM in VS automute threshold 6.5
(Amp: Play)
Att < 0.1dB; PO = 0.5W 7.5 8 V
VMUTE = 1.5V (Sourced current) 7 12 18 μA
Ipin23 Muting pin current
VMUTE = 3.5V -5 18 μA

HSD section

Vdropout Dropout Voltage IO = 0.35A; VS = 9 to 16V 0.25 0.6 V

Iprot Current Limits 400 800 mA

Offset detector (Pin 25)

VM_ON Mute voltage for DC offset detection 8 V

Vstby = 5V
VM_OFF enabled 6 V
VOFF Detected differential output offset Vstby = 5V; Vmute = 8V ±2 ±3 ±4 V
Vstby = 5V; Vmute = 8V
V25_T Pin 25 Voltage for detection = TRUE 0 1.5 V
VOFF > ±4V
Vstby = 5V; Vmute = 8V
V25_F Pin 25 Voltage for detection = FALSE 12 V
VOFF > ±2V
1. Saturated square wave output.

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Electrical specifications TDA7850

Figure 3. Standard test and application circuit

C8 C7
0.1μF 2200μF
Vcc1-2 Vcc3-4

R1 6 20
ST-BY 4 9
10K C9 8 OUT1
1μF
R2 7
MUTE 22
47K C10
1μF 5
C1
2 OUT2
IN1 11
3
0.1μF

IN2 12 17
C2 0.1μF 18 OUT3
19
IN3 15
C3 0.1μF
21
IN4 14 24 OUT4
C4 0.1μF S-GND 23
13
16 10 25 1
SVR HSD TAB
C5 C6
0.47μF D95AU335B
47μF

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TDA7850 Electrical specifications

Figure 4. P.C.B. and component layout of the Figure 3..

Components &
top copper layer

Bottom copper layer

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Application hints (ref. to the circuit of Figure 3) TDA7850

3 Application hints (ref. to the circuit of Figure 3)

3.1 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.

3.2 Input stage

The TDA7850'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.

3.3 Stand-by and muting

STAND-BY 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
kOhm 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.

3.4 DC offset detector

The TDA7850 integrates a DC offset detector to avoid an anomalous DC offset on the inputs
of the amplifier which may be multiplied by the gain, and result in a dangerous large offset
on the outputs, which may lead to speaker damage through overheating.
The feature is enabled by the MUTE pin and works with the amplifier unmuted and with no
signal on the inputs. The DC offset detection is signaled out on the HSD pin.

3.5 Heatsink definition

Under normal usage (4 Ohm speakers) the heatsink's thermal requirements have to be
deduced from fig. 18, 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 occurence (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 occurence even after long-term and full-volume operation.

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TDA7850 Package Information

4 Package Information

In order to meet environmental requirements, ST offers these devices in ECOPACK®

packages. These packages have a lead-free second level interconnect. 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 5. Flexiwatt25 (vertical) mechanical data & package dimensions

mm inch
DIM.
MIN. TYP. MAX. MIN. TYP. MAX.
A 4.45 4.50 4.65 0.175 0.177 0.183 OUTLINE AND
B 1.80 1.90 2.00 0.070 0.074 0.079 MECHANICAL DATA
C 1.40 0.055
D 0.75 0.90 1.05 0.029 0.035 0.041
E 0.37 0.39 0.42 0.014 0.015 0.016
F (1) 0.57 0.022
G 0.80 1.00 1.20 0.031 0.040 0.047
G1 23.75 24.00 24.25 0.935 0.945 0.955
H (2) 28.90 29.23 29.30 1.139 1.150 1.153
H1 17.00 0.669
H2 12.80 0.503
H3 0.80 0.031
L (2) 22.07 22.47 22.87 0.869 0.884 0.904
L1 18.57 18.97 19.37 0.731 0.747 0.762
L2 (2) 15.50 15.70 15.90 0.610 0.618 0.626
L3 7.70 7.85 7.95 0.303 0.309 0.313
L4 5 0.197
L5 3.5 0.138
M 3.70 4.00 4.30 0.145 0.157 0.169
M1 3.60 4.00 4.40 0.142 0.157 0.173
N 2.20 0.086
O 2 0.079
R 1.70 0.067
R1 0.5 0.02
R2 0.3 0.12
R3 1.25 0.049
R4 0.50 0.019
V
V1
5˚ (T p.)
3˚ (Typ.)
Flexiwatt25 (vertical)
V2 20˚ (Typ.)
V3 45˚ (Typ.)
(1): dam-bar protusion not included
(2): molding protusion included

B
V
H
H1
V3
H2 A
H3
O

R3

R4
L4

V1
R2
N
L2

R
L L1
V1
L3

V2

R2 D
R1

L5 R1 R1
Pin 1
E
G G1 F
FLEX25ME
M M1

7034862

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Package Information TDA7850

Figure 6. Flexiwatt25 (horizontal) mechanical data & package dimensions

mm inch
DIM.
MIN. TYP. MAX. MIN. TYP. MAX.
A 4.45 4.50 4.65 0.175 0.177 0.183 OUTLINE AND
B 1.80 1.90 2.00 0.070 0.074 0.079
C 1.40 0.055
MECHANICAL DATA
D 2.00 0.079
E 0.37 0.39 0.42 0.014 0.015 0.016
F (1) 0.57 0.022
G 0.75 1.00 1.25 0.029 0.040 0.049
G1 23.70 24.00 24.30 0.933 0.945 0.957
H (2) 28.90 29.23 29.30 1.139 1.150 1.153
H1 17.00 0.669
H2 12.80 0.503
H3 0.80 0.031
L (2) 21.64 22.04 22.44 0.852 0.868 0.883
L1 10.15 10.5 10.85 0.40 0.413 0.427
L2 (2) 15.50 15.70 15.90 0.610 0.618 0.626
L3 7.70 7.85 7.95 0.303 0.309 0.313
L4 5 0.197
L5 5.15 5.45 5.85 0.203 0.214 0.23
L6 1.80 1.95 2.10 0.070 0.077 0.083
M 2.75 3.00 3.50 0.108 0.118 0.138
M1 4.73 0.186
M2 5.61 0.220
N 2.20 0.086
P 3.20 3.50 3.80 0.126 0.138 0.15
R 1.70 0.067
R1 0.50 0.02
R2 0.30 0.12
R3 1.25 0.049
R4 0.50 0.02
V 5˚ (Typ.)
Flexiwatt25
V1
V2
3˚ (Typ.)
20˚ (Typ.)
(Horizontal)
V3 45˚ (Typ.)
(1): dam-bar protusion not included; (2): molding protusion included

7399733 A

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TDA7850 Revision history

5 Revision history

Table 4. Revision History

Date Revision Description of Changes

22-Nov-2006 1 First issue

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TDA7850

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