ST MICROELECTRONICS TDA 7381 Datasheet



4 x 25W QUAD BRIDGE CAR RADIO AMPLIFIER

HIGHOUTPUTPOWERCAPABILITY:
4 x30W/4Ω MAX.
4 x25W/4ΩEIAJ
4 x18W/4Ω@ 14.4V, 1KHz, 10%
4 x15W/4Ω @ 13.2V,1KHz,10%

CLIPPINGDETECTOR
LOW DISTORTION
LOW OUTPUTNOISE
ST-BYFUNCTION
MUTEFUNCTION
AUTOMUTEAT MIN. SUPPLY VOLTAGE DE-

TECTION
DIAGNOSTICSFACILITYFOR:

– CLIPPING
– OUT TOGND SHORT
– OUT TOV
– THERMALSHUTDOWN

LOW EXTERNALCOMPONENTCOUNT:
– INTERNALLYFIXED GAIN (26dB)
– NOEXTERNALCOMPENSATION
– NOBOOTSTRAPCAPACITORS

Protections:

OUTPUT SHORT CIRCUIT TO GND, TO V

SHORT

S

TDA7381

PRELIMINARY DATA

Flexiwatt25

ACROSSTHE LOAD
VERYINDUCTIVE LOADS
OVERRATING CHIP TEMPERATURE WITH

SOFTTHERMAL LIMITER
LOADDUMP VOLTAGE
FORTUITOUSOPEN GND
REVERSEDBATTERY
ESD PROTECTION

DESCRIPTION

The TDA7381 is a new technology class AB
Audio Power Amplifier in Flexiwatt 25 package

,

S

designed for car radio applications.

BLOCK AND APPLICATION DIAGRAM

Vcc1 Vcc2

ST-BY

MUTE

IN1

0.1µF

IN2

0.1µF

IN3

0.1µF

IN4

0.1µF

AC-GND

0.1µF47µF

September 1998

This is preliminary information on anew product now in development. Details are subject tochange without notice.

SVR TAB S-GND

DIAGN. OUT

OUT1+
OUT1­PW-GND

OUT2+
OUT2­PW-GND

OUT3+
OUT3­PW-GND

OUT4+
OUT4­PW-GND

D93AU002C

100nF2.200µF

1/10

TDA7381

DESCRIPTION(continued)

Thanks to the fully complementaryPNP/NPNout­put configurationthe TDA7381 allows a rail to rail
output voltage swing with no need of bootstrap
capacitors. The extremely reduced components
count allows very compact sets.

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

V

V

CC (DC)

V

CC (pk)

P

T

CC

I

O

tot

T

j

stg

Operating Supply Voltage 18 V
DC Supply Voltage 28 V
Peak Supply Voltage (t = 50ms) 50 V
Output Peak Current:

Repetitive (Duty Cycle 10% at f = 10Hz)
Non Repetitive(t = 100µs)

Power dissipation, (T

=70°C) 80 W

case

Junction Temperature 150
Storage Temperature – 40 to150

The on-board clipping detector simplifies gain
compression operations. The fault diagnostics
makes it possible to detect mistakes during Car­Radioassemblyand wiring in the car.

3
4

A
A

C

°

C

°

PIN CONNECTION

(Topview)

1 25

TAB

OUT2-

P-GND

ST-BY

CC

V

OUT2+

OUT1-

OUT1+

P-GND1

SVR

IN1

IN2

IN4

S-GND

IN3

OUT3+

AC-GND

OUT3-

P-GND3

CC

V

OUT4+

D94AU117B

MUTE

OUT4-

P-GND4

DIAGNOSTICS

THERMAL DATA

Symbol Parameter Value Unit

Thermal ResistanceJunction to Case Max. 1

2/10

R

th j-case

C/W

°

TDA7381

ELECTRICALCHARACTERISTICS

= 14.4V; f = 1KHz; Rg= 600Ω;RL=4Ω;T

(V

S

amb

=25°C;

Refer tothe Test and application circuit (fig.1), unless otherwisespecified.)

Symbol Parameter Test Condition Min. Typ. Max. Unit

I

q1

V

OS

G

v

P

o

P

o EIAJ

P

o max

THD Distortion P

e

No

SVR Supply Voltage Rejection f = 100Hz 50 65 dB

f

cl

f

ch

R

i

C

T

I

SB

V

SB out

V

SB IN

A

M

V

M out

V

Min

I

m (L)

I

CDOFF

I

CDON

(*) Saturated square wave output.
(**) Diagnostics output pulled-up to5V with 10KΩ series resistor.

Quiescent Current 180 300 mA
Output Offset Voltage 100 mV
Voltage Gain 25 26 27 dB
Output Power THD = 10%

THD = 1%
THD = 10%; V

THD = 1%; V

= 13.2V

S

= 13.2V

S

16.5
13

13.5
11

18
14

15

12
EIAJ Output Power(*) EIAJ (VS = 13.7V) 23 25 W
Max.Output Power (*) VS= 13.7V 28 30 W

= 4W 0.04 0.3 %

o

Output Noise ”A” Weighted

Bw = 20Hz to 20KHz

50

65 150

Low Cut-Off Frequency 20 Hz
High Cut-Off Frequency 75 KHz
Input Impedance 70 100 KΩ
Cross Talk f = 1KHz 50 70 dB
St-By Current Consumption St-By = LOW 100
St-By OUT ThresholdVoltage (Amp: ON) 3.5 V
St-By IN Threshold Voltage (Amp: OFF) 1.5 V
Mute Attenuation VO= 1Vrms 80 90 dB
Mute OUT Threshold Voltage (Amp: Play) 3.5 V
Mute IN Threshold Voltage (Amp: Mute) 1.5 V
Muting Pin Current V

MUTE

= 1.5V

51016µA

(Source Current)

Clipping Detector ”OFF” Output

THD = 1% (**) 100

Average Current
Clipping Detector ”ON” Output

THD = 10% (**) 100 240 350 µA

Average Current

W
W

W
W

µ
µV

µ

µ

V

A

A

3/10

TDA7381

Figure 1:

ST-BY

MUTE

IN1

IN2

IN3

IN4

StandardTestand Application Circuit

C8

0.1µF

R1

10K

R2

47K

C1

0.1µF

C2 0.1µF

C3 0.1µF

C4 0.1µF

C9

1µF

C10
1µF

S-GND

4

22

11

12

15

14

13

16 10 25 1

C5

0.1µF

C6

47µF

C7

2200µF

Vcc1-2 Vcc3-4

620

17
18
19

21
24
23

SVR TAB

9
8
7

5
2
3

OUT1

OUT2

OUT3

OUT4

D94AU179B

4/10

DIAGNOSTICS

TDA7381

Figure 2:

P.C.B.and component layout of the figure 1 (1:1scale)

COMPONENTS &
TOP COPPER LAYER

TDA7381

BOTTOM COPPER LAYER

5/10

TDA7381

APPLICATIONHINTS

(ref.to the circuit of fig. 1)
BIASING AND SVR
As shown by fig. 3, all the TDA7381’s main sec-

tions, such as INPUTS, OUTPUTS AND AC-GND
(pin 16) are internally biased at half Supply Volt­age level (Vs/2), which is derived from the Supply
VoltageRejection (SVR) block. In this way no cur­rent flowsthroughthe internalfeedbacknetwork.

The AC-GND is common to all the 4 amplifiers
and represents the connection point of all the in­verting inputs.

Both individual inputs and AC-GND are con­nected to Vs/2 (SVR) by means of 100KΩresis­tors.

To ensure proper operation and high supply volt­age rejection, it is of fundamental importance to
provide a good impedance matching between IN­PUTS and AC-GROUND terminations. This im­plies that C

1,C2,C3,C4,C5

CAPACITORSHAVE
TO CARRY THE SAME NOMINAL VALUE AND
THEIR TOLERANCE SHOULD NEVER EXCEED
±10 %.

Besides its contributionto 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 convenientlyserve both needs,

RECOMMENDED VALUE IS 10µF

ITS MINIMUM

.

INPUT STAGE
The TDA7381’S inputs are ground-compatible

and can stand very high input signals (± 8Vpk)
without any performancesdegradation.

If the standard value for the input capacitors

(0.1µF) is adopted, the low frequency cut-off will
amountto 16 Hz.

STAND-BYAND MUTING
STAND-BY and MUTING facilities are both

CMOS-COMPATIBLE. If unused, a straight con­nectionto Vs of theirrespective pinswould be ad­missible. Conventional low-power transistors can
be employedto drive muting and stand-bypins in
absence of true CMOS portsor microprocessors.

R-C cells have always to be used in order to
smooth down the transitions for preventing any
audibletransientnoises.

Since a DC current of about 10 uA normallyflows
out of pin 22, the maximum allowable muting-se­ries resistance (R

) is 70KΩ, which is sufficiently

2

high to permit a muting capacitor reasonably
small(about 1µF).

If R

is higher than recommended, the involved

2

risk will be that the voltage at pin 22 may rise to
above the 1.5 V threshold voltage and the device
will consequentlyfail to turn OFF when the mute
line is broughtdown.

About the stand-by, the time constant to be as­signed in order to obtain a virtually pop-freetran­sitionhas to be slower than 2.5V/ms.

DIAGNOSTICSFACILITY
The TDA7381 is equipped with a diagnostics cir-

cuitry able to detect the following events:

CLIPPINGin the outputstage
OVERHEATING (THERMAL SHUT-DOWN

proximity)

Figure 3:

6/10

Input/OutputBiasing.

V

S

10KΩ

SVR AC_GND

10KΩ

100KΩ

F

0.1µ

C1 ÷ C4

100KΩ70KΩ

47µ

F

C6

IN

0.1µ
C5

F

+

-

8KΩ

400Ω

400Ω

8KΩ

-

+

TOWARDS

OTHER CHANNELS

D95AU302

TDA7381

OUTPUT MISCONNECTIONS (OUT-GND &
OUT-Vsshorts)

Diagnostics information is available across an
open collector output located at pin 25 (fig. 4)
through a current sinking whenever at least one
of the above events is recognized.

Among them, the CLIPPING DETECTOR acts in
a way to output a signal as soon as one or more
power transistorsstartbeing saturated.

As a result, the clipping-related signal at pin 25

Figure 4:

Diagnosticscircuit.

25

TDA7385

TDA7381

R

VREF

Vpin 25

D95AU303

Figure5:

ClippingDetectionWaveforms.

takes the form of pulses, which are perfectly syn­cronized with each single clipping event in the
music program and reflect the same duration time
(fig. 5). Applications making use of this facility
usually operate a filtering/integrationof the pulses
train through passive R-C networks and realize a
volume (or tone bass) stepping down in associa­tion with microprocessor-drivenaudioprocessors.

The maximum load that pin 25 can sustain is
1KΩ.

Due to its operating principles, the clipping detec-

Figure 6: DiagnosticsWaveforms.

ST-BY PIN

VOLTAGE

MUTE PIN
VOLTAGE

Vs

OUTPUT

WAVEFORM

Vpin 25

WAVEFORM

t

t

t

D95AU304

CLIPPING

SHORT TO GND

OR TO Vs

t

THERMAL

PROXIMITY

7/10

TDA7381

Figure 7.

VREF

25

TDA7381

TDA7385

T1 <<

T2

VREF ≥ VREF1 >> VREF2

T1

T2

VREF1

VREF2

tor has to be viewed mainly as a power-depend­ent featurerather than frequency-dependent.This
means that clipping state will be immediately sig­naled out whenever a fixed power level is
reached,regardless of the audio frequency.

In other words, this feature offers the means to
counteract the extremely sound-damagingeffects
of clipping, caused by a sudden increase of odd
order harmonics and appearance of serious inter­modulationphenomena.

Another possible kind of distortion control could
be the setting of a maximum allowable THD limit
(e.g. 0.5 %) over the entire audio frequency
range. Besides offering no practical advantages,
this procedure cannot be much accurate, as the
non-clipping distortion is likely to vary over fre­quency.

In case of

OVERHEATING

, pin 25 will signal out
the junction temperature proximity to the thermal
shut-down threshold. This will typically start about

o

C before the thermal shut-down threshold is

2
reached.

As variouskind of diagnostics informationis avail­able at pin 25 (CLIPPING, SHORTS AND OVER­HEATING), it may be necessary to operatesome
distinctions on order to treat each event sepa­rately. This could be achieved by taking into ac­count the intrinsically different timing of the diag­nostics outputunder each circumstance.

In fact, clipping will produce pulses normally
much shorter than thosepresent under faulty con­ditions. An example of circuit able to distinguish
between the two occurrencesis shown by fig. 7.

-

+

-

+

CLIP DET. (TO

COMPRESSOR/

TONE CONTROL)

FAULT, THERMAL

(TO POWER SUPPLY

SECTION, µP

REGULATOR, FLASHING SYSTEM)

D95AU305

GAIN

SHUTDOWN

VOLTAGE

STABILITYANDLAYOUTCONSIDERATIONS
If properly layouted and hooked to standard car-

radio speakers, the TDA7381 will be intrinsically
stable with no need of external compensations
such as output R-C cells. Due to the high number
of channels involved, this translates into a very
remarkable components saving if compared to
similardeviceson the market.

To simplify pc-board layout designs, each ampli­fier stagehas its own power ground externally ac­cessible (pins 2,8,18,24)and one supply voltage
pin for eachcouple of them.

Even more important, this makes it possible to
achieve the highest possible degree of separation
among the channels, with remarkable benefitsin
termsof cross-talkand distortionfeatures.

About the layout grounding, it is particularly im­portant to connect the AC-GND capacitor (C

)to

5

the signal GND, as close as possibleto the audio
inputs ground: this will guaranteehigh rejectionof
any common mode spurious signals.

The SVR capacitor (C

) has also to be connected

6

to the signalGND.
Supply filtering elements (C

) have naturally

7,C8

to be connected to the power-ground and located
as close as possibleto theVs pins.

Pin 1, which is mechanically attached to the de­vice’s tab, needs to be tied to the cleanest power
ground point in the pc-board, which is generally
near the supplyfilteringcapacitors.

8/10

TDA7381

DIM.

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

mm inch

A 4.45 4.65 0.175 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 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 28.90 29.23 29.30 1.138 1.150 1.153
H1 17.00 0.669
H2 12.80 0.503
H3 0.80 0.031

L 21.57 21.97 22.37 0.849 0.865 0.880

L1 18.57 18.97 19.37 0.731 0.786 0.762
L2 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

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
R4 0.50 0.019
V2 20°
V3 45°

OUTLINE AND

MECHANICAL DATA

Flexiwatt25

L2

H

V3

H3

OL3

G

C

H1

G1

R3

H2

F

A

R4

N

R

L

L1

V2

D

M

E

M1

B

FLEX25

9/10

TDA7381

Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences
of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is
granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specification mentioned in this publication are
subject to change without notice. This publicationsupersedes and replaces all information previously supplied. STMicroelectronics products
are not authorized for use as criticalcomponents in life support devices or systems without express written approval of STMicroelectronics.

The ST logo is a registeredtrademark of STMicroelectronics

 1998 STMicroelectronics – Printed in Italy – AllRightsReserved

STMicroelectronics GROUP OF COMPANIES

Australia - Brazil - Canada -China- France - Germany -Italy - Japan - Korea - Malaysia - Malta- Mexico - Morocco -The Netherlands-

Singapore - Spain - Sweden- Switzerland- Taiwan - Thailand - United Kingdom- U.S.A.

http://www.st.com

10/10