STMicroelectronics TDA7850, TDA7850H Service Manual

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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

■ Excellent 2Ω driving capability

■ 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)
– No external compensation
– No bootstrap capacitors

■ On board 0.35A 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

■ ESD

, across the

s

TDA7850

4 x 50W MOSFET

Flexiwatt25

(Vertical)

Flexiwatt25

(Horizontal)

Description

The TDA7850 is a breakthrough MOSFET
technology class AB audio power amplifier in
Flexiwatt 25 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 minimised saturation losses,
sets new power references in the car-radio field,
with unparalleled distortion performances.

The TDA7850 integrates a DC offset detector.

Order codes

Part number Package Packing

TDA7850 Flexiwatt25 (Vertical) Tube

TDA7850H Flexiwatt25 (Horizontal) Tube

November 2006 Rev 1 1/14

www.st.com

1

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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

3/14

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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

ST-BY

MUTE

IN1

0.1μF

IN2

0.1μF

IN3

0.1μF

IN4

0.1μF

AC-GND

0.47μF47μF

SVR TAB S-GND

Figure 2. Pin connection (Top view)

TAB

P-GND2

OUT2-

ST-BY

OUT2+

V

OUT1-

P-GND1

OUT1+

SVR

IN1

IN2

S-GND

IN4

IN3

AC-GND

OUT3+

P-GND3

OUT3-

V

OUT4+

MUTE

OUT4-

P-GND4

HSD

CC

CC

1

25

D94AU159A

Ver tic al

TAB

P-GND2

OUT2-

ST-BY

OUT2+

V

OUT1-

P-GND1

OUT1+

SVR

IN1

IN2

S-GND

IN4

IN3

AC-GND

OUT3+

P-GND3

OUT3-

V

OUT4+

MUTE

OUT4-

P-GND4

HSD

100nF470μF

HSD

CC

CC

HSD/V

OUT1+

OUT1-

PW-GND

OUT2+

OUT2-

PW-GND

OUT3+

OUT3-

PW-GND

OUT4+

OUT4-

PW-GND

D94AU158D

1

25

OFF_DET

D06AU1655

Horizontal

5/14

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Electrical specifications TDA7850

2 Electrical specifications

Table 1. Absolute maximum ratings

Symbol Parameter Value Unit

V

V

CC (DC)

V

CC (pk)

Operating supply voltage 18 V

CC

DC Supply voltage 28 V

Peak supply voltage (for t = 50ms) 50 V

Output peak current

I

P

T

T

Table 2. Thermal data

repetitive (duty cycle 10% at f = 10Hz)

O

non repetitive (t = 100μs)

Power dissipation Tcase = 70°C 80 W

tot

Junction temperature 150 °C

j

Storage temperature -55 to 150 °C

stg

9

10

Symbol Parameter Value Unit

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

Table 3.

R

th j-case

Electrical characteristcs

(Refer to the test and application diagram, VS = 13.2V; RL = 4Ω; Rg = 600Ω; f = 1KHz; T
25°C; unless otherwise specified).

Symbol Parameter Test condition Min. Typ. Max. Unit

I

Quiescent current RL = ∞ 100 180 280 mA

q1

V

dV

Output offset voltage Play Mode ±60 mV

OS

During mute ON/OFF output offset
voltage

OS

During St-By ON/OFF output offset
voltage

±60 mV

±60 mV

A
A

amb

=

Voltage gain 25 26 27 dB

G

v

dG

Channel gain unbalance ±1 dB

v

= 13.2V; THD = 10%

V

S

= 13.2V; THD = 1%

V

S

= 14.4V; THD = 10%

V

S

VS = 14.4V; THD = 1%

Output power

P

o

= 13.2V; THD = 10%, 2Ω

V

S

VS = 13.2V; THD = 1%, 2Ω

= 14.4V; THD = 10%, 2Ω

V

S

= 14.4V; THD = 1%, 2Ω

V

S

P

o max.

Max. output power

(1)

VS = 14.4V; RL = 4Ω

= 14.4V; RL = 2Ω

V

S

6/14

23
16
28
20

42
32
50
40

25
19
30
23

45
34
55
43

50
80

W
W
W
W

W
W
W
W

W
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; T
25°C; unless otherwise specified).

Symbol Parameter Test condition Min. Typ. Max. Unit

P

= 4W

THD Distortion

e

Output noise

No

o

= 15W; RL = 2Ω

P

o

"A" Weighted
Bw = 20Hz to 20KHz

SVR Supply voltage rejection f = 100Hz; V

f

High cut-off frequency PO = 0.5W 100 300 KHz

ch

Input impedance 80 100 120 KΩ

R

i

f = 1KHz P
f = 10KHz P

V

y = 1.5V 20 μA

St-B

V

y = 0 10 μA

St-B

= 1.5V to 3.5V ±10 μA

St-By

= 4W 80 90 dB

Oref

I

I

pin5

V

SB out

V

SB in

A

V

M out

V

C

Cross talk

T

St-By Current consumption

SB

St-by pin current V

St-By Out threshold voltage (Amp: ON) 3.5 V

St-By in threshold voltage (Amp: OFF) 1.5 V

Mute attenuation P

M

Mute out threshold voltage (Amp: Play) 3.5 V

Mute in threshold voltage (Amp: Mute) 1.5 V

M in

(Amp: Mute)

V

AM in

VS automute threshold

Att ≥ 80dB; P
(Amp: Play)
Att < 0.1dB; P

V

I

pin23

Muting pin current

V

MUTE

MUTE

HSD section

= 1Vrms 50 70 dB

r

= 4W

O

= 4W

O

= 4W

Oref

= 0.5W

O

= 1.5V (Sourced current) 7 12 18 μA

= 3.5V -5 18 μA

60

6.5

0.006

0.015

35
50

70
60

7

7.5 8

0.05

0.07%%

5070μV

-

-

amb

μV

dB
dB

=

V

V

V

dropout

I

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

Current Limits 400 800 mA

prot

Offset detector (Pin 25)

V

M_ON

V

M_OFF

V

V

V

1. Saturated square wave output.

Mute voltage for DC offset detection
enabled

Detected differential output offset V

OFF

Pin 25 Voltage for detection = TRUE

25_T

Pin 25 Voltage for detection = FALSE

25_F

V

= 5V

stby

V
V

V
V

stby

stby

OFF

stby

OFF

= 5V; V

= 5V; V

> ±4V

= 5V; V

> ±2V

= 8V ±2 ±3 ±4 V

mute

= 8V

mute

mute

= 8V

01.5V

12 V

7/14

8V

6V

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Electrical specifications TDA7850

Figure 3. Standard test and application circuit

ST-BY

MUTE

IN1

IN2

IN3

IN4

R1

10K

R2

47K

C1

0.1μF

C2 0.1μF

C3 0.1μF

C4 0.1μF

C9

1μF

C10
1μF

S-GND

C8

0.1μF

4

22

11

12

15

14

13

16 10 25 1

C5

0.47μF

C7

2200μF

Vcc1-2

SVR TAB

C6

47μF

Vcc3-4

620

17

18

19

21

24

23

HSD

9

8

7

5

2

3

D95AU335B

OUT1

OUT2

OUT3

OUT4

8/14

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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

9/14

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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 T
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.

10/14

= 70°C and T

amb

= 150°C as boundary conditions, the

CHIP

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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

DIM.

A 4.45 4.50 4.65 0.175 0.177 0.183
B 1.80 1.90 2.00 0.070 0.074 0.079
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 1.1 53

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

V5˚ (Tp.)
V1 3˚ (Typ.)
V2 20˚ (Typ.)
V3 45˚ (Typ.)

(1): dam-bar protusion not included
(2): molding pr otusion included

mm inch

MIN. TYP. MAX. MIN. TYP. MAX.

V

B

H

V3

OL3 L4

L2

H1

H3

OUTLINE AND

MECHANICAL DATA

Flexiwatt25 (vertical)

C

V

H2

R3

R4

N

R2

R

L

L1

V2

A

V1

V1

Pin 1

R2

G

G1

F

FLEX25ME

R1

R1 R1

L5

D

E

M1

M

7034862

11/14

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Package Information TDA7850

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

DIM.

A 4 .45 4.50 4.65 0.175 0.177 0.183
B 1 .80 1.90 2.00 0.070 0.074 0.079
C 1.40 0.055
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 24.3 0 0.933 0.945 0.957

H (2) 28.90 29.23 29.3 0 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 0.3 13
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 0.0 83

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

V5˚ (Typ.)
V1 3˚ (Typ.)
V2 20˚ (Typ.)
V3 45˚ (Typ.)

(1): dam-bar protusion not included; (2): molding protus ion included

mm inch

MIN. TYP. MAX . MIN. TYP. MAX.

OUTLINE AND

MECHANICAL DATA

Flexiwatt25
(Horizontal)

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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

13/14

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TDA7850

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