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TDA7245 5w audio amplifier with muting and stand-by muting and stand-by functions voltage range up to 30v high supply voltage rejection svr typ = 50db (f = 100hz) music power = 12w (r l = 4 w , d = 10%) protection against chip over temperature description the TDA7245 is a monolithic integrated circuit in 9+9 powerdip package, intended for use as low frequency power amplifier in a wide range of applications in radio and tv sets. march 1995 figure 1: test and application circuit powerdip 9+9 ordering number: TDA7245 1/11
absolute maximum ratings symbol parameter value unit v s supply voltage 30 v i o output peak current (non repetitive t = 100 m s) 3 a i o output peak current (repetitive, f > 20hz) 2.5 a p tot power dissipation at t amb = 80 c at t case = 70 c 1 6 w w t stg , t j storage and junction temperature -40 to 150 c pin connection (top view) thermal data symbol description value unit r th j-case rth j-amb thermal resistance junction-case thermal resistance junction-ambient max max 15 70 c/w c/w TDA7245 2/11
electrical characteristics (refer to the test circuit, t amb = 25c, f = 1khz; unless otherwise specified). symbol parameter test condition min. typ. max. unit v s supply voltage 12 30 v v o quiescent output voltage v s = 24v 11.6 v i d quiescent drain current v s = 14v v s = 28v 17 21 35 ma ma p o output power d = 1%, f = 1khz v s = 14v, r l = 4 w v s = 18v, r l = 8 w d = 10%, f = 1khz v s = 14v, r l = 4 w v s = 18v, r l = 8 w music power (*) v s = 24v, d = 10%, r l = 4 w 4 4 4 5 5 12 w w w w w d harmonic distortion v s = 14v, r l = 4 w , p o = 50mw to 3w f = 1khz f = 10khz v s = 18v, r l = 8 w , p o = 50mw to 3.5w f = 1khz f = 10khz v s = 22v, r l = 16 w , p o = 50mw to 3w f = 1khz f = 10khz 0.15 0.8 0.12 0.5 0.08 0.4 0.5 % % % % % % r i input impedance f = 1khz 30 k w bw small signal bandwidth (-3db) p o = 1w; r l = 4 w v s = 14v 50 to 40,000 hz g v voltage gain (open loop) f = 1khz 75 db g v voltage gain (closed loop) f = 1khz 39 40 41 db e n total input noise b = 22 - 22,000hz r s = 50 w r s = 1k w r s = 10k w 1.7 2 36 mv m v m v s/n signal to noise ratio v s = 18v; r l = 8 w p o = 5w; r s = 10k w 86 db svr supply voltage rejection v s = 16.5v; r l = 8 w ; f = 100hz r s = 10k w; v r = 0.5vrms 40 50 db t sd thermal shut-down junction temperature 150 c mute function symbol parameter test condition min. typ. max. unit v m pin 4 dc voltage mute sw open (play) 6.4 v att m muting attenuation f = 100hz to 10khz 60 65 db TDA7245 3/11
electrical characteristcs (continued) stand-by function symbol parameter test condition min. typ. max. unit v st-by pin 5 dc voltage mute sw open (play) 6.4 v i st-by pin 5 current mute sw closed (st-by) 160 280 m a att st-by stand-by attenuation f = 100hz to 10khz 70 90 db v t stand-by threshold (pin 5) 3.8 v i d st-by stand-by current v s = 14v 1 3 ma 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. according to this definition our method of measurement comprises the following steps: 1) set the voltage supply at the maximum operating value -20% 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% 5) the music power is then v 2 out /r1 , where v out 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. figure 2: schematic diagram TDA7245 4/11
application suggestions the recommended values of the external components are those shown on the application circuit of fig.1. different values can be used. the following table can help the dsigner. component rec. value purpose larger than rec. value smaller than rec. value r1 20k w st-by biasing incorrect st-by function worse pop and shorter delay at st-by insertion r2(*) 27k w feedback resistors increase of gain decrease of gain r3(*) 270 w decrease of gain increase of gain r4 1 w frequency stability danger of oscillations c1 22 m f st-by capacitor longer on/off delay time at st-by in/out worse pop and shorter delay at st-by insertion c2 47 m f svr capacitor worse turn-on pop by v s and st-by degradation of svr c3 0.1 m f input capacitance higher low frequency cut-off c4 2.2 m f inverting input dc decoupling higher low frequency cut-off c5 470 m f supply voltage danger of oscillations c6 0.22 m f frequency stability danger of oscillations c7 1000 m f output dc decoupling higher low frequency cut-off (*) the value of closed loop gain (g v = 1 + r2/r3) must be higher than 25db. figure 3: p.c. board and components layout of the circuit of fig 2 (1:1 scale) TDA7245 5/11
figure 4: dc output voltage vs. supply voltage figure 6: output power vs. supply voltage figure 8: output power vs. supply voltage figure 5: i d vs. supply voltage figure 7: output power vs. supply voltage figure 9: distortion vs. output power TDA7245 6/11
figure 10: distortion vs. output power figure 12: supply voltage rejection vs. frequency (play) figure 14: power dissipation & efficiency vs. output power figure 11: distortion vs. output power figure 13: power dissipation & efficiency vs. output power figure 15: v pin5 (=v pin4 ) vs. supply voltage TDA7245 7/11
muting / stand- by the muting function allows to inhibit the output signal through an external control signal. it can be used in many cases, when a temporary inhibition of the output signal is requested, for ex- ample: C in switch-on condition, to avoid preamplifier power-on transients C during switching at the input stages C during the receiver tuning. the stand-by function is very useful and permits a complete turn on/off of the device through a low power signal, which can be provided by a m p. figure 17: i pin5 (st-by) vs. supply voltage figure 19: output attenuation vs. v pin5 figure 16: i pin4 (muting) vs. supply voltage figure 18: quiescent current (st-by) vs. supply voltage figure 20: quiescent current vs. v pin5 TDA7245 8/11
thermal shutdown the presence of a thermal limiting circuit offers the following advantages: 1)an overload on the output (even if it is perma- nent), or an above limit ambient temperature can be easily tolerated since the tj cannot be higher than 150 c. 2)the heatsink can have a smaller factor of safety compared with that of a conventional circuit. there is no possibility of device dam- age due to high junction temperature. if for any reason, the junction temperature in- crease up to 150 c, the thermal shutdown simply reduces the power dissipation and the current consumption. the maximum allowable power dissipation de- pends upon the junction-ambient thermal resis- tance. fig. 21 shows this dissipable power as a function of ambient temperature for different ther- mal resistance. figure 21: maximum allowable power dissipation vs. ambient temperature figure 22: example of heatsink using pc board copper (l = 65mm) mounting instructions the TDA7245 is assembled in the powerdip, in which 9 pins (from 10 to 18) are attached to the frame and remove the heat produced by the chip. figure 22 shows a pc board copper area used as a heatsink (l = 65mm). the thermal resis- tance junction-ambient is 35 c. TDA7245 9/11
powerdip 18 (9+9) package mechanical data dim. mm inch min. typ. max. min. typ. max. a1 0.51 0.020 b 0.85 1.40 0.033 0.055 b 0.50 0.020 b1 0.38 0.50 0.015 0.020 d 24.80 0.976 e 8.80 0.346 e 2.54 0.100 e3 20.32 0.800 f 7.10 0.280 i 5.10 0.201 l 3.30 0.130 z 2.54 0.100 TDA7245 10/11
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 f rom 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 s upplied. sgs- thomson microelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of sgs-thomson microelectronics. ? 1996 sgs-thomson microelectronics C printed in italy C all rights reserved sgs-thomson microelectronics group of companies australia - brazil - canada - china - france - germany - hong kong - italy - japan - korea - malaysia - malta - morocco - the n etherlands - singapore - spain - sweden - switzerland - taiwan - thailand - united kingdom - u.s.a. TDA7245 11/11

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