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TDA7381
4 x 18W BRIDGE CAR RADIO AMPLIFIER
PRODUCT PREVIEW

HIGH OUTPUT POWER CAPABILITY: 4 x 25W/4 EIAJ 4 x 18W/4 @ 14.4V, 1KHz, 10% 4 x 15W/4 @ 13.2V, 1KHz, 10% CLIPPING DETECTOR LOW DISTORTION LOW OUTPUT NOISE ST-BY FUNCTION MUTE FUNCTION AUTOMUTE AT MIN. SUPPLY VOLTAGE DETECTION DIAGNOSTICS FACILITY FOR: CLIPPING OUT TO GND SHORT OUT TO V S SHORT THERMAL SHUTDOWN LOW EXTERNAL COMPONENT COUNT: INTERNALLY FIXED GAIN (26dB) NO EXTERNAL COMPENSATION NO BOOTSTRAP CAPACITORS PROTECTIONS: OUTPUT SHORT CIRCUIT TO GND, TO VS, ACROSS THE LOAD BLOCK AND APPLICATION DIAGRAM
Vcc1

FLEXIWATT25

VERY INDUCTIVE LOADS OVERRATING CHIP TEMPERATURE WITH SOFT THERMAL LIMITER LOAD DUMP VOLTAGE FORTUITOUS OPEN GND REVERSED BATTERY ESD PROTECTION DESCRIPTION The TDA7381 is a new technology class AB Audio Power Amplifier in Flexiwatt 25 package designed for car radio applications.

Vcc2 2.200F 100nF

ST-BY DIAGN. OUT MUTE OUT1+ IN1 0.1F OUT1PW-GND OUT2+ IN2 0.1F OUT2PW-GND OUT3+ IN3 0.1F OUT3PW-GND OUT4+ IN4 0.1F AC-GND 0.1F SVR 47F TAB S-GND OUT4PW-GND

D93AU002C

May 1997
This is preliminary information on a new product now in development. Details are subject to change without notice.

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TDA7381
DESCRIPTION (continued) Thanks to the fully complementary PNP/NPN output configuration the 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 VCC VCC (DC) VCC (pk) IO Operating Supply Voltage DC Supply Voltage Peak Supply Voltage (t = 50ms) Output Peak Current: Repetitive (Duty Cycle 10% at f = 10Hz) Non Repetitive (t = 100s) Power dissipation, (Tcase = 70C) Junction Temperature Storage Temperature Parameter Value 18 28 50 3 4 80 150 40 to 150 Unit V V V A A W C C

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

Ptot Tj Tstg

PIN CONNECTION (Top view)

1

25

D94AU117B

THERMAL DATA
Symbol Rth j-case Parameter Thermal Resistance Junction to Case Max. Value 1 Unit C/W

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DIAGNOSTICS

AC-GND

P-GND4

P-GND1

P-GND3

P-GND

S-GND

SVR

OUT2+

OUT1+

OUT3+

OUT4+

ST-BY

MUTE

VCC

VCC

OUT4-

OUT2-

OUT1-

OUT3-

IN1

IN2

IN4

TAB

IN3

TDA7381
ELECTRICAL CHARACTERISTICS (VS = 14.4V; f = 1KHz; Rg = 600; RL = 4; Tamb = 25C; Refer to the Test and application circuit (fig.1), unless otherwise specified.)
Symbol Iq1 VOS Gv Po Parameter Quiescent Current Output Offset Voltage Voltage Gain Output Power THD = 10% THD = 1% THD = 10%; VS = 13.2V THD = 1%; VS = 13.2V Po max THD eNo SVR fcl fch Ri CT ISB VSB out VSB IN AM VM out VM in Im (L) Im (H) ICDOFF ICDON Max. Output Power Distortion Output Noise Supply Voltage Rejection Low Cut-Off Frequency High Cut-Off Frequency Input Impedance Cross Talk St-By Current Consumption St-By OUT Threshold Voltage St-By IN Threshold Voltage Mute Attenuation Mute OUT Threshold Voltage Mute IN Threshold Voltage Muting Pin Current Muting Pin Current Clipping Detector "OFF" Output Average Current Clipping Detector "ON" Output Average Current f = 1KHz St-By = LOW (Amp: ON) (Amp: OFF) VO = 1Vrms (Amp: Play) (Amp: Mute) VMUTE = 1.5V (Source Current) VMUTE = 3.5V (Source Current) THD = 1% (*) THD = 10% (*) 10 6 13 10 100 190 3.5 1.5 16 14 90 3.5 1.5 75 70 50 100 70 100 EIAJ RULES (VS = 13.7V) Po = 4W "A" Weighted Bw = 20Hz to 20KHz f = 100Hz 50 25 15 26 18 14 15 12 25 0.04 50 65 65 20 0.3 150 Test Condition Min. Typ. 180 150 27 Max. Unit mA mV dB W W W W W % V V dB Hz KHz K dB A V V dB V V A A A A

(*) Diagnostics output pulled-up to 5V with 10K series resistor.

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Figure 1: Standard Test and Application Circuit

C8 0.1F

C7 2200F Vcc1-2 Vcc3-4 6 20 9 8 OUT1

R1 ST-BY 10K R2 MUTE 47K C1 IN1 0.1F IN2 C2 0.1F IN3 C3 0.1F IN4 C4 0.1F S-GND 14 13 16 C5 0.1F SVR C6 47F 10 15 12 11 C10 1F C9 1F 22 4

7

5 2 3 OUT2

17 18 19 OUT3

21 24 23 25 1 TAB
D94AU179B

OUT4

DIAGNOSTICS

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Figure 2: P.C.B. and component layout of the figure 1 (1:1 scale) COMPONENTS & TOP COPPER LAYER TDA7381

BOTTOM COPPER LAYER

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TDA7381
APPLICATION HINTS (ref. to the circuit of fig. 1) BIASING AND SVR As shown by fig. 3, all the TDA7381's main sections, 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 Voltage Rejection (SVR) block. In this way no current flows through the internal feedback network. 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 100K resistors. 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 C1, C2, C3, C4, C5 CAPACITORS HAVE TO CARRY THE SAME NOMINAL VALUE AND THEIR TOLERANCE SHOULD NEVER EXCEED 10 %. 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 10F. INPUT STAGE The TDA7381'S inputs are ground-compatible and can stand very high input signals ( 8Vpk) without any performances degradation. If the standard value for the input capacitors Figure 3: Input/OutputBiasing.
100K + 0.1F C1 C4 IN 8K 400

(0.1F) is adopted, the low frequency cut-off will amount to 16 Hz. STAND-BY AND MUTING STAND-BY and MUTING facilities are both CMOS-COMPATIBLE. If unused, a straight connection to Vs of their respective pins would be admissible. Conventional low-power transistors can be employed to drive muting and stand-by pins in absence of true CMOS ports or microprocessors. R-C cells have always to be used in order to smooth down the transitions for preventing any audible transient noises. Since a DC current of about 10 uA normally flows out of pin 22, the maximum allowable muting-series resistance (R2) is 70K, which is sufficiently high to permit a muting capacitor reasonably small (about 1F). If R2 is higher than recommended, the involved risk will be that the voltage at pin 22 may rise to above the 1.5 V threshold voltage and the device will consequently fail to turn OFF when the mute line is brought down. 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. DIAGNOSTICS FACILITY The TDA7381 is equipped with a diagnostics circuitry able to detect the following events: CLIPPING in the output stage OVERHEATING (THERMAL proximity) SHUT-DOWN

400 VS 10K 70K 10K SVR 100K 47F C6 AC_GND 0.1F C5
D95AU302

8K + TOWARDS OTHER CHANNELS

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TDA7381
OUTPUT MISCONNECTIONS (OUT-GND & OUT-Vs shorts) 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 transistors start being saturated. As a result, the clipping-related signal at pin 25 Figure 4: Diagnostics circuit. Figure 5: Clipping Detection Waveforms.

25

R VREF

Vpin 25

TDA7385 TDA7381

D95AU303

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/integration of the pulses train through passive R-C networks and realize a volume (or tone bass) stepping down in association with microprocessor-driven audioprocessors. The maximum load that pin 25 can sustain is 1K. Due to its operating principles, the clipping detec-

Figure 6: Diagnostics Waveforms.
ST-BY PIN VOLTAGE

t

MUTE PIN VOLTAGE

t

Vs OUTPUT WAVEFORM t

Vpin 25 WAVEFORM t CLIPPING
D95AU304

SHORT TO GND OR TO Vs

THERMAL PROXIMITY

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TDA7381
Figure 7.

VREF

25

T1

+

T2 VREF1 -

CLIP DET. (TO GAIN COMPRESSOR/ TONE CONTROL) FAULT, THERMAL SHUTDOWN (TO POWER SUPPLY SECTION, P VOLTAGE REGULATOR, FLASHING SYSTEM)

TDA7381 TDA7385
VREF2

+

T1 << T2 VREF VREF1 >> VREF2

D95AU305

tor has to be viewed mainly as a power-dependent feature rather 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-damaging effects of clipping, caused by a sudden increase of odd order harmonics and appearance of serious intermodulation phenomena. 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 2 C before the thermal shut-down threshold is reached. As various kind of diagnostics information is available at pin 25 (CLIPPING, SHORTS AND OVERHEATING), it may be necessary to operate some distinctions on order to treat each event separately. This could be achieved by taking into account the intrinsically different timing of the diagnostics output under each circumstance. In fact, clipping will produce pulses normally much shorter than those present under faulty conditions. An example of circuit able to distinguish between the two occurrences is shown by fig. 7.

STABILITY AND LAYOUT CONSIDERATIONS If properly layouted and hooked to standard carradio 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 similar devices on the market. To simplify pc-board layout designs, each amplifier stage has its own power ground externally accessible (pins 2,8,18,24) and one supply voltage pin for each couple of them. Even more important, this makes it possible to achieve the highest possible degree of separation among the channels, with remarkable benefits in terms of cross-talk and distortion features. About the layout grounding, it is particularly important to connect the AC-GND capacitor (C5) to the signal GND, as close as possible to the audio inputs ground: this will guarantee high rejection of any common mode spurious signals. The SVR capacitor (C6) has also to be connected to the signal GND. Supply filtering elements (C7, C8) have naturally to be connected to the power-ground and located as close as possible to the Vs 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 supply filtering capacitors.

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FLEXIWATT25 PACKAGE MECHANICAL DATA
DIM. A B C D E F G G1 H H1 H2 H3 L L1 L2 L3 M M1 N O R R4 V2 V3 MIN. 4.45 1.80 0.75 0.37 0.80 23.75 28.90 mm TYP. 1.90 1.40 0.90 0.39 1.00 24.00 29.23 17.00 12.80 0.80 21.97 18.97 15.70 7.85 4.00 4.00 2.20 2 1.70 0.50 MAX. 4.65 2.00 1.05 0.42 0.57 1.20 24.25 29.30 MIN. 0.175 0.070 0.029 0.014 0.031 0.935 1.138 inch TYP. 0.074 0.055 0.035 0.015 0.040 0.945 1.150 0.669 0.503 0.031 0.865 0.786 0.618 0.309 0.157 0.157 0.086 0.079 0.067 0.019 MAX. 0.183 0.079 0.041 0.016 0.022 0.047 0.955 1.153

21.57 18.57 15.50 7.70 3.70 3.60

22.37 19.37 15.90 7.95 4.30 4.40

0.849 0.731 0.610 0.303 0.145 0.142

0.880 0.762 0.626 0.313 0.169 0.173

20 45

V3 H3 O

H H1 H2 R3 R4 A

L2

N
R L3 V2 L L1

D M E G G1 F M1 B C
FLEX25

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TDA7381

Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics 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 SGS-THOMSON Microelectronics. Specification mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. SGS-THOMSON Microelectronics products are not authorized for use as criticalcomponents in life support devices or systems without express written approval of SGS-THOMSON Microelectronics. 1997 SGS-THOMSON Microelectronics Printed in Italy All Rights Reserved SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Netherlands Singapore - Spain - Sweden - Switzerland - Taiwan - Thailand - United Kingdom - U.S.A.

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