TDA7385 4 x 30W QUAD BRIDGE CAR RADIO AMPLIFIER HIGH OUTPUT POWER CAPABILITY: 4 x 35W/4Ω MAX. 4 x 30W/4Ω EIAJ 4 x 22W/4Ω @ 14.4V, 1KHz, 10% 4 x 18.5W/4Ω @ 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, FLEXIWATT25 ORDERING NUMBER: TDA7385 ACROSS THE LOAD VERY INDUCTIVE LOADS OVERRATING CHIP TEMPERATURE WITH SOFT THERMAL LIMITER LOAD DUMP VOLTAGE FORTUITOUS OPEN GND REVERSED BATTERY ESD PROTECTION DESCRIPTION The TDA7385 is a new technology class AB Audio Power Amplifier in Flexiwatt 25 package BLOCK AND APPLICATION DIAGRAM Vcc1 Vcc2 2.200µF 100nF ST-BY DIAGN. OUT MUTE OUT1+ IN1 OUT10.1µF PW-GND OUT2+ IN2 OUT20.1µF PW-GND OUT3+ IN3 OUT30.1µF PW-GND OUT4+ IN4 OUT40.1µF PW-GND AC-GND 0.1µF SVR 47µF TAB S-GND D93AU002C October 1999 1/12 TDA7385 DESCRIPTION (continued) Thanks to the fully complementary PNP/NPN output configuration the TDA7385 allows a rail to rail output voltage swing with no need of bootstrap capacitors. The extremely reduced components count allows very compact sets. 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. ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit Operating Supply Voltage 18 V VCC (DC) DC Supply Voltage 28 V VCC (pk) Peak Supply Voltage (t = 50ms) 50 V Output Peak Current: Repetitive (Duty Cycle 10% at f = 10Hz) Non Repetitive (t = 100µs) 4.5 5.5 A A Power dissipation, (Tcase = 70°C) 80 W VCC IO Ptot Tj Junction Temperature 150 °C Tstg Storage Temperature – 55 to 150 °C designed for high end car radio applications. PIN CONNECTION (Top view) D94AU117B P-GND4 DIAGNOSTICS MUTE OUT4- VCC OUT4+ OUT3- OUT3+ P-GND3 IN3 AC-GND IN4 IN2 S-GND IN1 SVR OUT1+ P-GND1 VCC OUT1- ST-BY OUT2+ OUT2- TAB 25 P-GND 1 THERMAL DATA 2/12 Symbol Parameter Rth j-case Thermal Resistance Junction to Case Max. Value Unit 1 °C/W TDA7385 ELECTRICAL CHARACTERISTICS (VS = 14.4V; f = 1KHz; Rg = 600Ω; RL = 4Ω; Tamb = 25°C; Refer to the Test and application circuit (fig.1), unless otherwise specified.) Symbol Parameter Iq1 Quiescent Current VOS Output Offset Voltage Gv Voltage Gain Po Output Power Po EIAJ EIAJ Output Power (*) Test Condition mV 27 dB THD = 10%; VS = 14V THD = 5%; VS = 14V THD = 1%; VS = 14V 19 17 16 21 19 17 W W W THD = 10%; VS = 13.2V THD = 1%; VS = 13.2V 17 14 18.5 15 W W VS = 13.7V 27.5 30 W 33 eNo Output Noise ”A” Weighted Bw = 20Hz to 20KHz SVR Supply Voltage Rejection f = 100Hz 35 0.04 50 65 50 W 0.3 % 150 µV µV 65 dB 20 Hz 75 Ri Input Impedance CT Cross Talk f = 1KHz ISB St-By Current Consumption St-By = LOW VSB out St-By OUT Threshold Voltage (Amp: ON) VSB IN St-By IN Threshold Voltage (Amp: OFF) Mute Attenuation VO = 1Vrms 80 VM out Mute OUT Threshold Voltage (Amp: Play) 3.5 VM in Mute IN Threshold Voltage (Amp: Mute) Im (L) Muting Pin Current VMUTE = 1.5V (Source Current) ICDOFF Clipping Detector ”OFF” Output Average Current THD = 1% (**) ICDON Clipping Detector ”ON” Output Average Current THD = 10% (**) AM mA 100 W W VS = 14.4V High Cut-Off Frequency Unit 26 Po = 4W fch 300 22 18 Max. Output Power (*) Low Cut-Off Frequency Max. 180 25 Distortion fcl Typ. 20 16.5 THD = 10% THD = 1% THD Po max. Min. KHz 70 100 50 70 KΩ dB 100 3.5 1.5 5 90 V dB V 10 1.5 V 16 µA µA 100 100 µA V 240 350 µA (*) Saturated square wave output. (**) Diagnostics output pulled-up to 5V with 10KΩ series resistor. 3/12 TDA7385 Figure 1: Standard Test and Application Circuit C8 0.1µF C7 2200µF Vcc1-2 Vcc3-4 6 R1 ST-BY 20 9 4 10K R2 C9 1µF MUTE 8 22 47K C10 1µF 5 C1 2 11 IN1 17 12 18 C2 0.1µF IN3 C3 0.1µF 21 IN4 24 14 S-GND C5 0.1µF OUT4 23 13 16 10 25 SVR C6 47µF 1 TAB D94AU179B DIAGNOSTICS 4/12 OUT3 19 15 C4 0.1µF OUT2 3 0.1µF IN2 OUT1 7 TDA7385 Figure 2: P.C.B. and component layout of the figure 1 (1:1 scale) COMPONENTS & TOP COPPER LAYER TDA7385 BOTTOM COPPER LAYER 5/12 TDA7385 Figure 3: Quiescent Current vs. Supply Voltage Figure 4: Quiescent Output Voltage vs. Supply Voltage Figure 5: Output Power vs. Supply Voltage Figure 6: Distortion vs. Output Power Figure 7: Distortion vs. Frequency. Figure 8: Supply Voltage Rejection Frequency by varying C6 R g = 600Ω Vripple = 1Vrms 6/12 vs. TDA7385 Figure 9: Output Noise vs. Source Resistance Figure 10: Power Dissipation & Efficiency vs. Output Power Ptot (W) Ptot R g (Ω) APPLICATION HINTS (ref. to the circuit of fig. 1) BIASING AND SVR As shown by fig. 11, all the TDA7385’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 100KΩ 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 10µF. Figure 11: Input/OutputBiasing. 100KΩ + 0.1µF C1 ÷ C4 8KΩ IN 400Ω 400Ω VS 8KΩ 10KΩ 70KΩ 10KΩ SVR 100KΩ AC_GND 47µF C6 0.1µF C5 + TOWARDS OTHER CHANNELS D95AU302 7/12 TDA7385 INPUT STAGE The TDA7385’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 (0.1µF) 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 70KΩ, which is sufficiently high to permit a muting capacitor reasonably small (about 1µF). 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. tion with microprocessor-driven audioprocessors. The maximum load that pin 25 can sustain is 1KΩ. Due to its operating principles, the clipping detector has to be viewed mainly as a power-dependFigure 12: Diagnostics circuit. R 25 VREF Vpin 25 TDA7385 D95AU303 Figure 13: Clipping Detection Waveforms. DIAGNOSTICS FACILITY The TDA7385 is equipped with a diagnostics circuitry able to detect the following events: CLIPPING in the output stage OVERHEATING (THERMAL SHUT-DOWN proximity) OUTPUT MISCONNECTIONS (OUT-GND & OUT-Vs shorts) Diagnostics information is available across an open collector output located at pin 25 (fig. 12) 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 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. 13). 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 associa8/12 ent 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 TDA7385 Figure 14: Diagnostics Waveforms. ST-BY PIN VOLTAGE t MUTE PIN VOLTAGE t Vs OUTPUT WAVEFORM t Vpin 25 WAVEFORM t CLIPPING SHORT TO GND OR TO Vs D95AU304 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. THERMAL PROXIMITY 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. 15. STABILITY AND LAYOUT CONSIDERATIONS If properly layouted and hooked to standard carradio speakers, the TDA7385 will be intrinsically stable with no need of external compensations Figure 15. VREF T1 25 + T2 VREF1 - TDA7385 T1 << T2 VREF ≥ VREF1 >> VREF2 + CLIP DET. (TO GAIN COMPRESSOR/ TONE CONTROL) FAULT, THERMAL SHUTDOWN (TO POWER SUPPLY SECTION, µP VOLTAGE REGULATOR, FLASHING SYSTEM) VREF2 D95AU305 9/12 TDA7385 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 im- 10/12 portant 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. TDA7385 DIM. A B C D E F (1) G G1 H (2) H1 H2 H3 L (2) L1 L2 (2) L3 L4 L5 M M1 N O R R1 R2 R3 R4 V V1 V2 V3 MIN. 4.45 1.80 0.75 0.37 0.80 23.75 28.90 22.07 18.57 15.50 7.70 3.70 3.60 mm TYP. 4.50 1.90 1.40 0.90 0.39 1.00 24.00 29.23 17.00 12.80 0.80 22.47 18.97 15.70 7.85 5 3.5 4.00 4.00 2.20 2 1.70 0.5 0.3 1.25 0.50 MAX. 4.65 2.00 MIN. 0.175 0.070 1.05 0.42 0.57 1.20 24.25 29.30 0.029 0.014 0.031 0.935 1.138 22.87 19.37 15.90 7.95 0.869 0.731 0.610 0.303 4.30 4.40 0.145 0.142 inch TYP. 0.177 0.074 0.055 0.035 0.015 0.040 0.945 1.150 0.669 0.503 0.031 0.884 0.747 0.618 0.309 0.197 0.138 0.157 0.157 0.086 0.079 0.067 0.02 0.12 0.049 0.019 MAX. 0.183 0.079 OUTLINE AND MECHANICAL DATA 0.041 0.016 0.022 0.047 0.955 1.153 0.904 0.762 0.626 0.313 0.169 0.173 5° (Typ.) 3° (Typ.) 20° (Typ.) 45° (Typ.) Flexiwatt25 (1): dam-bar protusion not included (2): molding protusion included H H1 V3 A H2 O H3 R3 L4 R4 V1 R2 L2 N L3 R L L1 V1 V2 R2 D R1 L5 R1 R1 E G V G1 F M M1 B C V FLEX25ME 11/12 TDA7385 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 publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. 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