TDA7296A 70V - 60W DMOS AUDIO AMPLIFIER WITH MUTE/ST-BY PRODUCT PREVIEW VERY HIGH OPERATING VOLTAGE RANGE (35V) DMOS POWER STAGE HIGH OUTPUT POWER (UP TO 60W MUSIC POWER) MUTING/STAND-BY FUNCTIONS NO SWITCH ON/OFF NOISE NO BOUCHEROT CELLS VERY LOW DISTORTION VERY LOW NOISE SHORT CIRCUIT PROTECTION THERMAL SHUTDOWN CLIPPING DETECTION OUTPUT DESCRIPTION The TDA7296A is a monolithic integrated circuit in Multiwatt15 package, intended for use as audio class AB amplifier in Hi-Fi field applications (Home Stereo, self powered loudspeakers, Topclass TV). Thanks to the wide voltage range and to the high out current capability it is able to supply the highest power into both 4 and 8 loads MULTIPOWER BCD TECHNOLOGY Multiwatt 15 ORDERING NUMBER: TDA7296AV even in presence of poor supply regulation, with high Supply Voltage Rejection. The built in muting function with turn on delay simplifies the remote operation avoiding switching on-off noises. The device provides a circuit for the detection of clipping in the output stages. The output, on open collector, is able to drive system with automatic level control. Figure 1: Typical Application and Test Circuit C7 100nF +Vs C6 1000F R3 22K C2 22F R2 680 C1 470nF IN- 2 IN+ 3 +Vs +PWVs 7 13 - 14 + R1 22K CD IN+MUTE VM R5 10K VSTBY 4 MUTE 10 STBY 9 R4 22K C3 10F C4 10F OUT C5 22F 6 5 BOOTSTRAP +5V MUTE THERMAL SHUTDOWN STBY S/C PROTECTION 1 8 15 STBY-GND -Vs -PWVs C9 100nF C8 1000F D96AU494 -Vs June 1996 This is preliminary information on a new product now in development. Details are subject to change without notice. 1/13 TDA7296A PIN CONNECTION (Top view) 15 -VS (POWER) 14 OUT 13 +VS (POWER) 12 N.C. 11 N.C. 10 MUTE 9 STAND-BY 8 -VS (SIGNAL) 7 +VS (SIGNAL) 6 BOOTSTRAP 5 CD 4 SVR 3 NON INVERTING INPUT 2 INVERTING INPUT 1 STAND-BY GND D96AU495 BLOCK DIAGRAM BOOTSTRAP +VS + + BOOTSTRAP IN+ OUTPUT IN- CD CD + - + -VS BIPOLAR TRANSCONDUCTANCE INPUT STAGE MOS GAIN & LEVEL SHIFTING STAGE MOS OUTPUT STAGE SHORT CIRCUIT PROTECTION D96AU496 ABSOLUTE MAXIMUM RATINGS Symbol Value Unit VS Supply Voltage 35 V IO Ptot Output Peak Current Power Dissipation Tcase = 70C 5 50 A W 0 to 70 150 C C Top Tstg, Tj 2/13 Parameter Operating Ambient Temperature Range Storage and Junction Temperature TDA7296A THERMAL DATA Symbol Rth j-case Description Thermal Resistance Junction-case Value Unit 1.5 C/W Max ELECTRICAL CHARACTERISTICS (Refer to the Test Circuit VS = 24V, RL = 8, GV = 30dB; Rg = 50 ; Tamb = 25C, f = 1 kHz; unless otherwise specified. Symbol Parameter VS Iq Operating Supply Range Quiescent Current Ib Test Condition Min. Typ. Max. Unit 10 20 30 35 60 V mA Input Bias Current 500 nA VOS Input Offset Voltage +10 mV IOS Input Offset Current +100 nA PO RMS Continuous Output Power d d = 0.5%: VS = 24V, RL = 8 VS = 21V, RL = 6 S = 18V, RL = 4 Music Power (RMS) (*) t = 1s d = 10%; RL = 8 ; VS = 29V RL = 6 ; VS = 24V RL = 4; VS = 22V Total Harmonic Distortion (**) PO = 5W; f = 1kHz PO = 0.1 to 20W; f = 20Hz to 20kHz 27 27 27 Slew Rate GV Open Loop Voltage Gain GV Closed Loop Voltage Gain eN Total Input Noise 60 60 60 W W W 0.1 0.01 7 24 A = curve f = 20Hz to 20kHz Frequency Response (-3dB) PO = 1W Ri SVR Input Resistance Supply Voltage Rejection f = 100Hz; Vripple = 0.5Vrms % % 0.1 % % V/s 30 40 dB 1 2 5 V V 10 80 fL, fH TS W W W 0.005 VS = 18V, RL = 4: PO = 5W; f = 1kHz PO = 0.1 to 20W; f = 20Hz to 20kHz SR 30 30 30 dB 20Hz to 20kHz 100 60 Thermal Shutdown k 75 dB 145 C STAND-BY FUNCTION (Ref: -VS or GND) VST on Stand-by on Threshold VST off ATTst-by Stand-by off Threshold Stand-by Attenuation 1.5 3.5 70 Quiescent Current @ Stand-by Iq st-by MUTE FUNCTION (Ref: -VS or GND) VMon Mute on Threshold VMoff Mute off Threshold ATTmute Mute AttenuatIon DC Off Clipping detector OFF. CD output Duty Cycle Clipping detector On. CD output Duty Cycle DC On 3.5 60 V dB 90 1 V 3 mA 1.5 V V 80 dB THD = 1% TBD % THD = 10% TBD % Note (*): MUSIC POWER is the maximal power which the amplifier is capable of producing across the rated load resistance (regardless of non linearity) 1 sec after the application of a sinusoidal input signal of frequency 1KHz. Note (**): Tested with optimized Application Board (see fig. 2) 3/13 TDA7296A Figure 2: P.C.B. and components layout of the circuit of figure 1. (1:1 scale) TDA7296A Note: The Stand-by and Mute functions can be referred either to GND or -VS. On the P.C.B. is possible to set both the configuration through the jumper J1. 4/13 TDA7296A APPLICATION SUGGESTIONS (see Test and Application Circuits of the Fig. 1) The recommended values of the external components are those shown on the application circuit of Figure 1. Different values can be used; the following table can help the designer. LARGER THAN SUGGESTED SMALLER THAN SUGGESTED INCREASE INPUT IMPRDANCE DECREASE INPUT IMPEDANCE COMPONENTS SUGGESTED VALUE PURPOSE R1 (*) 22k INPUT RESISTANCE R2 680 R3 (*) 22k R4 22k ST-BY TIME CONSTANT LARGER ST-BY ON/OFF TIME SMALLER ST-BY ON/OFF TIME; POP NOISE R5 10k MUTE TIME CONSTANT LARGER MUTE ON/OFF TIME SMALLER MUTE ON/OFF TIME C1 0.47F INPUT DC DECOUPLING HIGHER LOW FREQUENCY CUTOFF C2 22F FEEDBACK DC DECOUPLING HIGHER LOW FREQUENCY CUTOFF C3 10F MUTE TIME CONSTANT LARGER MUTE ON/OFF TIME SMALLER MUTE ON/OFF TIME C4 10F ST-BY TIME CONSTANT LARGER ST-BY ON/OFF TIME SMALLER ST-BY ON/OFF TIME; POP NOISE C5 22F BOOTSTRAPPING SIGNAL DEGRADATION AT LOW FREQUENCY C6, C8 1000F SUPPLY VOLTAGE BYPASS DANGER OF OSCILLATION C7, C9 0.1F SUPPLY VOLTAGE BYPASS DANGER OF OSCILLATION CLOSED LOOP GAIN DECREASE OF GAIN INCREASE OF GAIN SET TO 30dB (**) INCREASE OF GAIN DECREASE OF GAIN (*) R1 = R3 FOR POP OPTIMIZATION (**) CLOSED LOOP GAIN HAS TO BE 24dB 5/13 TDA7296A TYPICAL CHARACTERISTICS (Application Circuit of fig 1 unless otherwise specified) Figure 3: Output Power vs. Supply Voltage. Figure 4: Distortion vs. Output Power Figure 5: Output Power vs. Supply Voltage Figure 6: Distortion vs. Output Power Figure 7: Distortion vs. Frequency Figure 8: Distortion vs. Frequency 6/13 TDA7296A TYPICAL CHARACTERISTICS (continued) Figure 9: Quiescent Current vs. Supply Voltage Figure 10: Supply Voltage Rejection vs. Frequency Figure 11: Mute Attenuation vs. Vpin10 Figure 12: St-by Attenuation vs. Vpin9 Figure 13: Power Dissipation vs. Output Power Figure 14: Power Dissipation vs. Output Power 7/13 TDA7296A INTRODUCTION In consumer electronics, an increasing demand has arisen for very high power monolithic audio amplifiers able to match, with a low cost the performance obtained from the best discrete designs. The task of realizing this linear integrated circuit in conventional bipolar technology is made extremely difficult by the occurence of 2nd breakdown phenomenon. It limits the safe operating area (SOA) of the power devices, and as a consequence, the maximum attainable output power, especially in presence of highly reactive loads. Moreover, full exploitation of the SOA translates into a substantial increase in circuit and layout complexity due to the need for sophisticated protection circuits. To overcome these substantial drawbacks, the use of power MOS devices, which are immune from secondary breakdown is highly desirable. The device described has therefore been developed in a mixed bipolar-MOS high voltage technology called BCD 80. 1) Output Stage The main design task one is confronted with while developing an integrated circuit as a power operational amplifier, independently of the technology used, is that of realising the output stage. The solution shown as a principle schematic by Fig 15 represents the DMOS unity-gain output buffer of the TDA7296A. This large-signal, high-power buffer must be capable of handling extremely high current and voltage levels while maintaining acceptably low har- monic distortion and good behaviour over frequency response; moreover, an accurate control of quiescent current is required. A local linearizing feedback, provided by differential amplifier A, is used to fullfil the above requirements, allowing a simple and effective quiescent current setting. Proper biasing of the power output transistors alone is however not enough to guarantee the absence of crossover distortion. While a linearization of the DC transfer characteristic of the stage is obtained, the dynamic behaviour of the system must be taken into account. A significant aid in keeping the distortion contributed by the final stage as low as possible is provided by the compensation scheme, which exploits the direct connection of the Miller capacitor at the amplifier's output to introduce a local AC feedback path enclosing the output stage itself. 2) Protections In designing a power IC, particular attention must be reserved to the circuits devoted to protection of the device from short circuit or overload conditions. Due to the absence of the 2nd breakdown phenomenon, the SOA of the power DMOS transistors is delimited only by a maximum dissipation curve dependent on the duration of the applied stimulus. In order to fully exploit the capabilities of the power transistors, the protection scheme implemented in this device combines a conventional SOA protection circuit with a novel local temperature sensing technique which " dynamically" controls the maximum dissipation. Figure 15: Principle Schematic of a DMOS unity-gain buffer. 8/13 TDA7296A Figure 16: Turn ON/OFF Suggested Sequence +Vs (V) +35 -35 -Vs VIN (mV) VST-BY PIN #9 (V) VMUTE PIN #10 (V) 5V 5V IP (mA) VOUT (V) OFF ST-BY PLAY MUTE ST-BY OFF MUTE D93AU013 In addition to the overload protection described above, the device features a thermal shutdown circuit which initially puts the device into a muting state (@ Tj = 145 oC) and then into stand-by (@ Figure 17: Single Signal ST-BY/MUTE Control Circuit MUTE MUTE/ ST-BY STBY 20K 10K 30K 1N4148 10F 10F D93AU014 Tj = 150 oC). Full protection against electrostatic discharges on every pin is included. 3) Other Features The device is provided with both stand-by and mute functions, independently driven by two CMOS logic compatible input pins. The circuits dedicated to the switching on and off of the amplifier have been carefully optimized to avoid any kind of uncontrolled audible transient at the output. The sequence that we recommend during the ON/OFF transients is shown by Figure 16. The application of figure 17 shows the possibility of using only one command for both st-by and mute functions. On both the pins, the maximum applicable range corresponds to the operating supply voltage. 9/13 TDA7296A 4) Clipping Detector Output The TDA7296A is equipped with an internal circuit able to detect the output stage saturation providing a proper current sinking into on open collector output (pin 5) when a certain distortion level is reached at output. This particular function allows gain compression facility whenever the amplifier is overdriven, thus obtaining high quality sound all listening levels. BRIDGE APPLICATION Another application suggestion is the BRIDGE configuration, where two TDA7296A are used, as shown by the schematic diagram of figure 19. In this application, the value of the load must not be lower than 8 Ohm for dissipation and current capability reasons. A suitable field of application includes HI-FI/TV subwoofers realizations. The main advantages offered by this solution are: - High power performances with limited supply voltage level. - Considerably high output power even with high load values (i.e. 16 Ohm). The characteristics shown by figures 21 and 22, measured with loads respectively 8 Ohm and 16 Ohm. With Rl= 8 Ohm, Vs = 18V the maximum output power obtainable is 60W, while with Rl=16 Ohm, Vs = 24V the maximum Pout is 60W. Figure 18: Clipping Detector Output Waveform VO OUTPUT SIGNAL ICLIP S96AU498 t Figure 19: Bridge Application Circuit +Vs 0.22F 2200F 7 3 Vi 0.56F 13 6 + 22K 14 22F - 22K 2 1 4 ST-BY/MUTE 10 680 9 15 8 20K 22K 22F 10 10K 30K 9 15 8 22F 6 3 0.56F -Vs 0.22F 2200F 1N4148 + 22K 14 2 1 4 7 13 22F 22K 680 D96AU497 10/13 TDA7296A Figure 20: Frequency Response of the Bridge Application Figure 21: Distortion vs. Output Power Figure 22: Distortion vs. Output Power 11/13 TDA7296A MULTIWATT15 PACKAGE MECHANICAL DATA mm DIM. MIN. TYP. MAX. MIN. TYP. MAX. A 5 B 2.65 0.104 C 1.6 0.063 D 0.197 1 E 0.49 0.039 0.55 0.019 0.022 F 0.66 0.75 0.026 G 1.14 1.27 1.4 0.045 0.050 0.055 G1 17.57 17.78 17.91 0.692 0.700 0.705 H1 19.6 L 0.030 0.772 H2 12/13 inch 20.2 22.1 22.6 0.795 0.870 0.890 L1 22 22.5 0.866 0.886 L2 17.65 18.1 0.695 0.713 L3 17.25 17.5 17.75 0.679 0.689 0.699 L4 10.3 10.7 10.9 0.406 0.421 0.429 L7 2.65 2.9 0.104 0.114 M 4.2 4.3 4.6 0.165 0.169 0.181 M1 4.5 5.08 5.3 0.177 0.200 0.209 S 1.9 2.6 0.075 0.102 S1 1.9 2.6 0.075 0.102 Dia1 3.65 3.85 0.144 0.152 TDA7296A 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. SGSTHOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of SGS-THOMSON Microelectronics. (c) 1996 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. 13/13