TDA7298V

TDA7298 ® 28W Hi-Fi AUDIO POWER AMPLIFIER WITH MUTE / STAND-BY SUPPLY VOLTAGE RANGE UP TO ±22V SPLIT SUPPLY OPERATION HIGH OUTPUT POWER (UP TO 28W MUSIC POWER) LOW DISTORTION MUTE/STAND-BY FUNCTION NO SWITCH ON/OFF NOISE AC SHORT CIRCUIT PROTECTION THERMAL SHUTDOWN ESD PROTECTION Heptawatt ORDERING NUMBER: TDA7298 DESCRIPTION The TDA7298 is a monolithic integrated circuit in Heptawatt package, intended for use as audio class AB amplifier in TV or Hi-Fi field application. Thanks to the wide voltage range and to the high out current capability it’s able to supply the highTEST AND APPLICATION CIRCUIT ) s ( ct c u d ) s t( est power into both 4Ω and 8Ω loads even in presence of poor supply regulation. The built in Muting/Stand-by function simplifies the remote operations avoiding also switching onoff noises. e t le o r P o s b O - u d o r P e t e l o s b O September 2003 1/11 TDA7298 ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit ±22 V VS DC Supply Voltage IO Output Peak Current (internally limited) 4 A Ptot Power Dissipation Tcase = 70°C 30 W Top Operating Temperature Range 0 to +70 °C -40 to +150 °C Tstg, Tj Storage and Junction Temperature PIN CONNECTION (Top view) c u d e t le BLOCK DIAGRAM ) s ( ct u d o r P e t e l o s b O 2/11 o s b O - o r P ) s t( TDA7298 THERMAL DATA Symbol Rth j-case Description Thermal Resistance Junction-case Max Value Unit 2.5 °C/W ELECTRICAL CHARACTERISTICS (Refer to the test circuit, GV = 32dB; VS + 18V; f = 1KHz; Tamb = 25°C, unless otherwise specified.) Symbol Parameter VS Supply Range Iq Total Quiescent Current Ib Test Condition Min. Typ. +6 VS = +22V 20 40 Max. Unit +22 V 70 mA Input Bias Current +0.5 µA VOS IOS Input Offset Voltage +15 mV +200 nA PO Music Output Power IEC268-3 Rules (*) VS = + 20, RL = 8Ω, d = 10%, t = 1s PO Output Power (continuous RMS) d = 10% RL = 4Ω VS = +14V RL = 8Ω Input Offset Current 28 20 20 RL = 8Ω PO = 0.1 to 10W; f = 100Hz to 15KHz SR Slew Rate GV Open Loop Voltage Gain eN Total Input Noise so ) s ( ct Supply Voltage Rejection Thermal Shutdown TS b O - 3 A Curve f = 20Hz to 20KHz Input Resistance Ri SVR e t le o r P f = 100Hz, Vripple = 1VRMS ) s t( W W 17 17 RL = 4Ω VS = +14V PO = 0.1 to 10W; f = 100Hz to 15KHz Total Harmonic Distortion 24 24 c u d d = 1% RL = 4Ω VS = +14V RL = 8Ω d W 0.1 0.7 0.1 0.5 % V/µs 80 dB 10 500 du % 5 2 3 40 W W µV µV KΩ 50 dB 145 °C MUTE/STAND-BY FUNCTION (Ref. –VS) o r P e VTST-BY Stand-by - Threshold VTPLAY Play Threshold t e l o Iq ST-BY ATTST-BY bs Ipin3 Quiescent Current @ Stand-by Stand-by Attenuation 1 Vpin 3 = 0.5V Pin 3 Current @ Stand-by 70 1.8 V 2.7 4 V 1 90 3 mA dB –1 +10 µA Note (*): MUSIC POWER CONCEPT MUSIC POWER is ( according to the IEC clauses n.268-3 of Jan 83) 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. O According to this definition our method of measurement comprises the following steps: 1) Set the voltage supply at the maximum operating value -10% 2) Apply a input signal in the form of a 1KHz tone burst of 1 sec duration; the repetition period of the signal pulses is > 60 sec 3) The output voltage is measured 1 sec from the start of the pulse 4) Increase the input voltage until the output signal show a THD = 10% 2 5) The music power is then V out/R1, where Vout is the output voltage measured in the condition of point 4) and R1 is the rated load impedance The target of this method is to avoid excessive dissipation in the amplifier. 3/11 TDA7298 APPLICATIONS SUGGESTIONS (See Test and Application Circuit) The recommended values of the external components are those shown on the application circuit. Different values can be used; the following table can help the designer. Comp. Value R1 22KΩ (*) Purpose Larger Than Input Impedance R2 560Ω R3 22KΩ (*) Closed Loop Gain set to 32dB (**) R4 R5 22KΩ (*) 22KΩ Input Impedance @ Mute Stand-by Time Constant Smaller Than Increase of Input Impedance Decrease of Gain Decrease of Input Impedance Increase of Gain Increase of Gain Decrease of Gain R6 4.7Ω Frequency Stability C1 1µF Input DC Decoupling Danger of oscillations Higher Low-frequency cut-off Danger of oscillations C2 10µF Feedback DC Decoupling Higher Low-frequency cut-off C3 10µF Stand-by Time Constant C4 0.100µF Frequency Stability C5, C6 1000µF Supply Voltage Bypass c u d (*) R1 = R3 = R4 for POP optimization (**) Closed Loop Gain has to be ≥ 30dB e t le ) s ( ct TYPICAL CHARACTERISTICS Figure 1: Output Power vs. Supply Voltage u d o r P e t e l o s b O 4/11 ) s t( Danger of Oscillations o r P o s b O - Figure 2: Distortion vs. Output Power TDA7298 Figure 3: Output Power vs. Supply Voltage. Figure 5: Distortion vs. Frequency. Figure 4: Distortion vs. Output Power. c u d Figure 6: Distortion vs. Frequency. e t le ) s ( ct u d o r P e Figure 7: Quiescent Current vs. Supply Voltage ) s t( o r P o s b O - Figure 8: Supply Voltage Rejection vs. Frequency. t e l o s b O 5/11 TDA7298 Figure 9: Bandwidth. Figure 10: Output Attenuation & Quiescent Current vs. Vpin3. Figure 11: Total Power Dissipation & Efficiency vs. Output Power. c u d Figure 12: Total Power Dissipation & Efficiency vs. Output Power. e t le ) s ( ct u d o r P e t e l o s b O 6/11 ) s t( o s b O - o r P TDA7298 Figure 13: P.C. Board and Components Layout of the Circuit of Fig. 14 (1:1 scale) c u d e t le Figure 14: Demo Board Schematic. ) s ( ct ) s t( o r P o s b O - u d o r P e t e l o s b O 7/11 TDA7298 MUTE/STAND-BY FUNCTION The pin 3 (MUTE/STAND-BY) controls the amplifier status by three different thresholds, referred to -VS. When its voltage is lower than the first threshold (1V, with a +70mV hysteresis), the amplifier is in STAND-BY and all the final stage current gener- ators are off. Only the input MUTE stage is on in order to prevent pop-on problems. At Vpin3=1.8V the final stage current generators are switched on and the amplifier operates in MUTE. For Vpin3 =2.7V the amplifier is definitely on (PLAY condition) Figure 15. c u d e t le ) s ( ct u d o r P e t e l o s b O 8/11 o s b O - o r P ) s t( TDA7298 SHORT-CIRCUIT PROTECTION The TDA7298 has an original circuit which protects the device during accidental short-circuit between output and GND / -Vs / +Vs, taking it in STAND-BY mode, so limiting also dangerous DC current flowing throught the loudspeaker. If a short-circuit or an overload dangerous for the final transistors are detected, the concerned SOA circuit sends out a signal to the latching circuit (with a 10µs delay time that prevents fast random spikes from inadvertently shutting the amplifier off) which makes Q1 and Q2 saturate (see Block Diagram). Q1 immediately short-circuits to ground the A point turning the final stage off while Q2 short-circuits to ground the external capacitor driving the pin 3 (Mute/Stand-by) towards zero potential. Only when the pin 3 voltage becomes lower than 1V, the latching circuit is allowed to reset itself and restart the amplifier, provided that the shortcircuit condition has been removed. In fact, a window comparator is present at the output and it is aimed at preventing the amplifier from restarting if the output voltage is lower than 0.35 Total Supply Voltage or higher than 0.65 Total Supply Voltage. If the output voltage lies between these two thresholds, one may reasonably suppose the short-circuit has been removed and the amplifier may start operating again. The PLAY/MUTE/STAND-BY function pin (pin 3) is both ground- and positive supply-compatible and can be interfaced by means of the R5, C3 net either to a TTL or CMOS output (µ-Processor) or to a specific application circuit. The R5, C3 net is fundamental, because connecting this pin directly to a low output impedance driver such as TTL gate would prevent the correct operation during a short-circuit. Actually a final stage overload turns on the protection latching circuit that makes Q2 try to drive the pin 3 voltage under 0.8 V. Since the maximum current this pin can stand is 3 mA, one must make sure the following condition is met: (s) THERMAL PROTECTION The thermal protection operates on the 125µA current generator, linearly decreasing its value from 90°C on. By doing this, the A voltage slowly decreases thus switching the amplifier first to MUTE (at 145°C) and then to STAND-BY (155°C). Figure 16: Thermal Protection Block Diagram c u d e t le ) s t( o r P The maximum allowable power dissipation depends on the size of the external heatsink (thermal resistance case-ambient); figure 17 shows the dissipable power as a function of ambient temperature for different thermal resistance. o s b O - t c u Figure 17: Maximum Allowable Power Dissipation vs. Ambient Temperature. d o r P e t e l o R5 ≥ (VA − 0.7V) 3mA s b O that yields: R5, min = 1.5 KΩ with VA=5V. In order to prevent pop-on and -off transients, it is advisable to calculate the C3, R5 net in such a way that the STAND-BY/MUTE and MUTE/PLAY threshold crossing slope (positive at the turn-on and vice-versa) is less than 100 V/sec. 9/11 TDA7298 DIM. MIN. A C D D1 E E1 F G G1 G2 H2 H3 L L1 L2 L3 L4 L5 L6 L7 L9 L10 L11 M M1 V4 Dia 2.4 1.2 0.35 0.7 0.6 2.34 4.88 7.42 10.05 16.7 21.24 22.27 2.6 15.1 6 2.1 4.3 2.55 4.83 mm TYP. 2.54 5.08 7.62 16.9 14.92 21.54 22.52 2.8 15.5 6.35 0.2 MAX. 4.8 1.37 2.8 1.35 0.55 0.97 0.8 2.74 5.28 7.82 10.4 10.4 17.1 21.84 22.77 1.29 3 15.8 6.6 inch TYP. MIN. 0.094 0.047 0.014 0.028 0.024 0.095 0.193 0.295 0.100 0.200 0.300 0.396 0.657 0.668 0.587 0.848 0.891 0.386 0.877 0.102 0.594 0.236 0.110 0.610 0.250 0.008 2.7 0.082 4.8 0.169 3.05 0.100 5.33 0.190 40 (typ.) 3.85 0.144 2.8 5.08 3.65 0.110 0.200 MAX. 0.189 0.054 0.110 0.053 0.022 0.038 0.031 0.105 0.205 0.307 0.409 0.409 0.673 OUTLINE AND MECHANICAL DATA Weight: 1.90gr 0.860 0.896 0.051 0.118 0.622 0.260 c u d 0.106 0.190 0.120 0.210 o r P Heptawatt V e t le 0.152 L ) s t( o s b O E L1 ct A C u d o D1 r P e L5 (s) M D H2 L2 L3 F E t e l o s b O M1 E1 V4 L9 G H3 G1 G2 Dia. F L10 L4 H2 L11 L7 L6 10/11 HEPTAMEC 0016069 TDA7298 c u d e t le ) s ( ct ) s t( o r P o s b O - u d o r P e t e l o s b O 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. Specifications 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. The ST logo is a registered trademark of STMicroelectronics. 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