View TDA7460NDTR_5935781.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

device includes audio processor, stereo decoder, noiseblanker and multipath detector high performance signal proces- sor no external components required fully programmable via i 2 c bus low distortion low noise description the tda7460n is a high performance signal processor specifically designed for car radio ap- plications. the device includes a complete audioprocessor and a stereo decoder with noiseblanker, stereoblend and all signal processing functions necessary for state-of-the-art as well as future car radio systems. switched-capacitors design technique allows to obtain all these features without external compo- nents or adjustments. this means that higher quality and reliability walks alongside an overall cost saving. the csp is fully programmable by i 2 c bus inter- face allowing to customize key device parameters and especially filter characteristics. the bicmos process combined with the opti- mized signal processing assure low noise and low distortion performances. june 2000 ? supply loudness demodulator + stereo adjust + stereo blend cref out lr d97au629a digital control pilot cancellation v s cass l input multiplexer + auto zero phone gnd (mpout) beep mpx mixing stage volume bass treble out lr out lf out rr out rf out lf out rr out rf scl sda 80khz lp fm r fm l pll 25khz lp s & h high cut control multipath- detector pulse former d level cdl cdg cdr am cass r phone (mpin) gnd smute phone soft mute pil det i 2 c bus noise blanker a 8 1 2 7 6 9 15 14 20 3 4 5 11 17 19 16 18 12 13 10 block diagram so20 ordering number: tda7460nd tda7460n car radio signal processor 1/31
absolute maximum ratings symbol parameter value unit v s operating supply voltage 10.5 v t amb operating ambient temperature range -40 to 85 c t stg storage temperature range -55 to 150 c supply symbol parameter test condition min. typ. max. unit v s supply voltage 7.5 9 10 v i s supply current v s = 9v 25 30 35 ma svrr ripple rejection @ 1khz audioprocessor (all filters flat) 60 db stereodecoder + audioprocessor 45 db esd all pins are protected against esd according to the mil883 standard. thermal data symbol parameter value unit r th-j pins thermal resistance junction-pins max 85 c/w cass r cass l cdr cdgnd cdl phone (mpin) phgnd (mpout) am mpx scl sda gnd out rr v s out lr out rf out lf cref 1 3 2 4 5 6 7 8 9 18 17 16 15 14 12 13 11 19 10 20 level smute d97au628a pin connection tda7460n 2/31
pin description n. name function type 1 cassr cassette input right i 2 cassl cassette input left i 3 cdr cd right channel input i 4 cdgnd ground reference cd i 5 cdl cd left channel input i 6 phgnd phone ground (mpout selectable by sw 1 )i 7 phone phone input (mpin selectable by sw 1 )i 8 am am input i 9 mpx fm input (mpx) i 10 level level input stereodecoder i 11 smute soft mute drive i 12 scl i 2 c clock line i/o 13 sda i 2 c data line i/o 14 gnd supply ground s 15 vs supply voltage s 16 outrr right rear speaker output o 17 outlr left rear speaker output o 18 outrf right front spaeaker output o 19 outlf left front speaker output o 20 cref reference capacitor pin s (1) see input configuration tree and databyte specification "configuration" pin type legenda: i = input o = output i/o = input/output s = supply tda7460n 3/31
audio processor part input multiplexer fully differential or quasi-differential cd and cassette stereo input am mono or stereo input phone differential or single ended input internal beep with 2 frequencies (selectable) mixable phone and beep signals loudness first or second order frequency response programmable center frequency and quality factor 15 x 1db steps selectable flat-mode (constant attenuation) volume control 1db attenuator max. gain 20db max. attenuation 79db soft-step gain control bass control 2nd order frequency response center frequency programmable in 4(5) steps dc gain programmable 7 x 2db steps treble control 2nd order frequency response center frequency programmable in 4 steps 7 x 2db steps speaker control 4 independent speaker controls (1db steps control range 50db) mute functions direct mute digitally controlled softmute with 4 program- mable time constants electrical characteristics (v s = 9v; t amb = 25c; r l = 10k w ; all gains = 0db; f = 1khz; unless otherwise specified). symbol parameter test condition min. typ. max. unit input selector r in input resistance all inputs except phone 70 100 130 k w v cl clipping level 2.2 2.6 v rms s in input separation 80 100 db g in min min. input gain -1 0 1 db g in max max. input gain 13 14 15 db g step step resolution 1 2 3 db v dc dc steps adjacent gain step -5 0 +5 mv g min to g max -5 1 +5 mv differential cd stereo input r in input resistance differential 70 100 130 k w common mode 20 30 40 k w cmrr common mode rejection ratio v cm = 1 vrms @ 1khz 45 70 db v cm = 1 vrms @ 10khz 45 60 db e n output noise @ speaker output 20hz to 20khz flat; all stages 0db 915 m v differential phone input r in input resistance differential 10 15 20 k w common mode 20 30 40 k w cmrr common mode rejection ratio v cm = 1 vrms @ 1khz 45 70 db v cm = 1 vrms @ 10khz 45 60 db tda7460n 4/31
electrical characteristics (continued) symbol parameter test condition min. typ. max. unit beep control v rms beep level 250 350 500 mv f bmin lower beep frequency 570 600 630 hz f bmax higher beep frequency 1.15 1.2 1.25 khz mixing control m level mixing level source -1 0 1 db source -5 -6 -7 db source -10 -12 -14 db beep/phone -1 0 1 db volume control g max max gain 19 20 21 db a max max attenuation -83 -79 -75 db a step step resolution 0.5 1 1.5 db e a attenuation set error g = -20 to 20db -1.25 0 1.25 db g = -60 to 20db -4 0 3 db e t tracking error 2db v dc dc steps adjacent attenuation steps -3 0.1 3 mv from 0db to g min -7 0.5 +7 mv loudness control a step step resolution 0.5 1 1.5 db a max max. attenuation -16 -15 -14 db f cmin lower center frequency 180 200 220 hz f cmax higher center frequency 360 400 440 hz soft mute a mute mute attenuation 60 100 db t d delay time t1 0.48 1 ms t2 0.96 2 ms t3 20 40.4 60 ms t4 200 324 600 ms v thlow low threshold for sm pin 1 1v v thhigh high threshold for sm pin 2.5 v r pu internal pull-up resistor 70 100 130 k w v pu pull-up voltage 4.7 v soft step t sw switch time 5 10 15 ms 1) the sm pin is active low (mute = 0) tda7460n 5/31
electrical characteristics (continued) symbol parameter test condition min. typ. max. unit bass control c range control range 13 14 15 db a step step resolution 1 2 3 db f c center frequency f c1 54 60 66 hz f c2 63 70 77 hz f c3 72 80 88 hz f c4 90 100 (2) 110 hz q bass quality factor q 1 0.9 1 1.1 q 2 1.11.251.4 q 3 1.3 1.5 1.7 q 4 1.8 2 2.2 dc gain bass-dc-gain dc = off -1 0 +1 db dc = on 4 4.4 6 db treble control c range control range 13 14 15 db a step step resolution 1 2 3 db f c center frequency f c1 8 10 12 khz f c2 10 12.5 15 khz f c3 12 15 18 khz f c4 14 17.5 21 khz speaker attenuators c range control range -53 -50 -47 db a step step resolution 0.5 1 2 db a mute output mute attenuation 80 90 db e e attenuation set error -2 2 db v dc dc steps adjacent attenuation steps 0.1 5 mv audio outputs v clip clipping level d = 0.3% 2.2 2.6 v rms r l output load resistance 2 k w c l output load capacitance 10 nf r out output impedance 30 100 w v dc dc voltage level 3.6 3.8 4.0 v general e no output noise bw = 20 hz to 20 khz output muted 315 m v bw = 20 hz to 20 khz all gain = 0db 6.5 15 m v s/n signal to noise ratio all gain = 0db flat; v o = 2v rms 106 db bass treble at 12db; v o = 2.6v rms 100 db d distortion v in = 1v rms ; all stages 0db 0.002 0.1 % v in = 1v rms ; bass & treble = 12db 0.05 0.1 % s c channel separation left/right 80 100 db e t total tracking error a v = 0 to -20db -1 0 1 db a v = -20 to -60db -2 0 2 db 2) see description of audioprocessor part - bass & treble filter characteristics programming tda7460n 6/31
description of the audioprocessor part programmable input matrix the programmable input matrix of the tda7460n offers several possibilities to adapt the audioproc- essor to the desired application. in to the stand- ard application we have: cd quasi differential cassette stereo phone differential am mono stereodecoder input. the input matrix can be configured by only 2 bits: bits 3 and 4 of subaddress 0. basically the bit of subaddress 13 is fixed by the application and has to be programmed only once at the startup of the ic. for many configurations the two bits are also fixed during one application (e.g. the standard ap- plication) and a change of the input source can be done by loading the first three bits of subad- dress 0. in other configurations for some sources a pro- gramming of bit 3 and 4 of subaddress 0 is nec- essary in addition to the three source selection bits. in every case only the subaddress 0 has to be changed to switch from one source to another. the following picture shows the input and source programming flow: tda7460 cd qd cd fd appl. 2 appl. 1 appl. 3 appl. 5 appl. 4 appl. 6 cd qd cassette fm std am mono phone (d) cd qd cassette fm std am stereo phone (se) cd qd cassette fm std am std phone (d) cd fd cassette fm std am mono phone (se) cd fd cassette fm std am stereo cd fd cassette fm std am std phone (se) d98au851 no multipath cd fd multipath cd qd appl. 8 appl. 7 cd qd cassette fm std am mono cd qd cassette fm std am std figure 1. input configuration tree note: in amstd configuration the am mono signal is lead through the fm stereodecoder part to use its additional filters and high-cut function. tda7460n 7/31
how to find the right input configuration the best way to come to the desired configura- tion may be to go through the application tree from the top to the bottom while making the spe- cific decisions. this way will lead to one of the six possible appli- cations. then take the number of the application and go into the pinning table. here you will find the special pinout as well as the special program- ming codes for selecting sources. for example in appl. 6 the tda7460n has to be configured while startup with the databyte 0/xxxx0xxx. to select the fm, am or phone source the last five significant bits of subaddress 0 have to be changed, for any other source the last three bits are sufficient (see data byte specification). input stages most of the input circuits are the same as in pre- ceeding st audioprocessors with exception of the cd inputs (see figure 2). in the meantime there are some cd players in the market having a significant high source im- pedance which affects strongly the common- mode rejection of the normal differential input stage. the additional buffer of the cd input avoids this drawback and offers the full common- mode rejection even with those cd players. the tda7460n can be configured with an addi- tional input; if the ac coupling before the speaker stage is not used (bit 7 in subaddress 5 set to "1") acinl and acinr pins can be used as an addi- tional stereo input. autozero in order to reduce the number of pins there is no ac coupling between the in-gain and the follow- ing stage, so that any offset generated by or be- fore the in-gain stage would be transferred or even amplified to the output. to avoid that effect a special offset cancellation stage called autozero is implemented. to avoid audible clicks the audioprocessor is muted before the loudness stage during this time. in some cases, for example if the m p is executing a refresh cycle of the i 2 c bus programming, it is not useful to start a new autozero action because no new source is selected and an undesired mute would appear at the outputs. for such applica- tions the tda7460n could be switched in the "auto zero remain" mode (bit 6 of the subad- dress byte). if this bit is set to high, the dat- abyte 0 could be loaded without invoking the autozero and the old adjustment value remains. pin number appl. no 4 6 7 8 programming 1) 1cd gnd phone gnd phone am mono startup: 0/xxx11xxx 2cd gnd phone am right am left startup: 0/xxxx1xxx fm am phone 0/xxx11100 0/xxx01011 0/xxx11010 3cd gnd phone gnd phone amstd startup: 0/xxxx1xxx fm am phone 0/xxx11100 0/xxx01100 0/xxx11010 4 cdr gnd cdl gnd phone am mono startup: 0/xxxx0xxx 5 cdr gnd cdl gnd amright am left startup: 0/xxxx0xxx fm am 0/xxx10100 0/xxx00011 6 cdr gnd cdl gnd phone amstd startup: 0/xxxx0xxx fm am phone 0/xxx10100 0/xxx00100 0/xxx10010 7cd gnd mpout mpin am mono startup: 0/xxx11xxx 8cd gnd mpout mpin am std startup: 0/xxx1xxx fm am 0/xxx11100 0/xxx01100 1) syntax 0/xxx11100 means: subaddress = 0 - data byte = xxx11100 (x - dont care) tda7460n 8/31
mixing stage this stage offers the possibility to mix the internal beep or the phone signal to any other source. due to the fact that the mixing stage is also lo- cated behind the in-gain stage fine adjustments of the main source level can be done in this way. loudness there are four parameters programmable in the loudness stage (see fig. 3, 4, 5): - attenuation - center frequency - loudness q - flat mode: in this mode the loudness stage works as a 0 - 15db attenuator. softmute the digitally controlled softmute stage allows muting/demuting the signal with a i 2 c bus pro- grammable slope. the mute process can either be activated by the softmute pin or by the i 2 c bus. the slope is realized in a special s shaped curve to mute slow in the critical regions (see fig- ure 6). for timing purposes the bit 3 of the i 2 c bus out- put register is set to 1 from the start of muting un- til the end of demuting. 15k 15k 100k cd cdgnd 15k 15k - + 15k 15k phone ph_gnd 15k 15k - + d97au633a 100k 100k 100k stereodecoder in gain cassette am mpx figure 2. input stages -20.0 -15.0 -10.0 -5.0 0.0 10.0 100.0 1.0k 10.0k figure 3. loudness attenuation @ fc = 400hz (second order) -20.0 -15.0 -10.0 -5.0 0.0 10.0 100.0 1.0k 10.0k figure 4. loudness center frequency @ attn. = 15db (second order) tda7460n 9/31
softstep volume when volume level is changed often an audible click appears at the output. the root cause of those clicks could be either a dc offset before the volume stage or the sudden change of the envelope of the audio signal. with the softstep feature both kinds of clicks could be reduced to a minimum and are no more audible (see figure 7). bass there are three parameters programmable in the bass stage (see figs 8, 9, 10, 11): - attenuation - center frequency (60, 70, 80 and 100hz) - quality factors (1, 1.25, 1.5 and 2) dc mode in this mode the dc gain is increased by 4.4db. in addition the programmed center frequency and quality factor is decreased by 25% which can be used to reach alternative center frequencies or quality factors. treble there are two parameters programmable in the treble stage (see figs 12, 13): - attenuation - center frequency (10, 12.5, 15 and 17.5khz). speaker attenuator due to practical aspects the steps in the speaker attenuators are not linear over the full range. at attenuations more than 24db the steps increase from 1.5db to 10db (please see data byte specifi- cation). 10 100 1,000 hz -20 -15 -10 -5 (db) d98au844 figure 5. loudness @ attn. = 15db, fc = 400hz 1 ext. mute +signal ref -signal 1 i 2 c bus out time d97au634 figure 6. softmute timing 2db 1db -1db -2db time d97au635 vout 10ms figure 7. soft step timing note: please notice that a started mute action is always terminated and could not be interrupted by a change of the mute signal. note: for steps more than 1db the softstep mode should be deactivated because it could generate a 1db error during the blend-time tda7460n 10/31
0.0 2.5 5.0 7.5 10.0 12.5 15.0 10.0 100.0 1.0k 10.0k figure 11. bass normal and dc mode @ gain = 14db, fc = 80hz 0.0 2.5 5.0 7.5 10.0 12.5 15.0 10.0 100.0 1.0k 10.0k figure 10. bass quality factors @ gain = 14db, fc = 80hz 0.0 2.5 5.0 7.5 10.0 12.5 15.0 10.0 100.0 1.0k 10.0k figure 9. bass center @ gain = 14db, q = 1 -15.0 -10.0 -5.0 0.0 5.0 10.0 15.0 10.0 100.0 1.0k 10.0k figure 8. bass control @ fc = 80hz, q = 1 0.0 2.5 5.0 7.5 10.0 12.5 15.0 10.0 100.0 1.0k 10.0k figure 13. treble center frequencies @ gain = 14db -15.0 -10.0 -5.0 0.0 5.0 10.0 15.0 10.0 100.0 1.0k 10.0k figure 12. treble control @ fc = 17.5khz note: in general the center frequency, q and dc-mode can be set independently. the exception from this rule is the mode (5/xx1111xx) where the center frequency is set to 150hz instead of 100hz. tda7460n 11/31
stereodecoder part no external components necessary pll with adjustment free fully integrated vco automatic pilot dependent mono/stereo switching very high suppression of intermodulation and interference programmable roll-off compensation dedicated rds softmute highcut and stereoblend characterisctics pro- grammable in a wide range internal noiseblanker with threshold controls multipath detector with programmable inter- nal/external influence i 2 c bus control of all necessary functions electrical characteristics (v s = 9v; deemphasis time constant = 50 m s, v mpx = 500mv, 75khz deviation, f = 1khz. g i = 6db, t amb = 25c; unless otherwise specified). symbol parameter test condition min. typ. max. unit v in mpx input level input gain = 3.5db 0.5 1.25 v rms r in input resistance 70 100 130 k w g min minimum input gain 1.5 3.5 4.5 db g max max input gain 8.5 11 12.5 db g step step resolution 1.75 2.5 3.25 db svrr supply voltage ripple rejection v ripple = 100mv, f = 1khz 55 db a max channel separation 30 50 db thd total harmonic distortion 0.02 0.3 % s + n n signal plus noise to noise ratio s = 2v rms 80 91 db mono/stereo switch v pthst1 pilot threshold voltage for stereo, pth = 1 10 15 25 mv v pthst0 pilot threshold voltage for stereo, pth = 0 15 25 35 mv v pthmo1 pilot threshold voltage for mono, pth = 1 7 12 17 mv v pthmo0 pilot threshold voltage for stereo, pth = 0 10 19 25 mv pll d f/f capture range 0.5 % deemphasis and highcut (5) t hc50 deemphasis time constant bit = 7, subadr. 10 = 0 v level >> v hch 25 50 75 m s t hc75 deemphasis time constant bit = 7, subadr. 10 = 1 vlevel >> v hch 50 75 100 m s t hc50 highcut time constant bit = 7, subadr. 10 = 0 vlevel >> v hcl 100 150 200 m s t hc75 highcut time constant bit = 7, subadr. 10 = 1 vlevel >> v hcl 150 225 300 m s stereoblend and highcut-control ref5v internal reference voltage 4.7 5 5.3 v tc ref5v temperature coefficient 3300 ppm l gmin min. level gain -1 0 +1 db l gmax max. level gain 8 10 12 db l gstep level gain step resolution 0.3 0.67 1.0 db vsbl min min.voltage for mono 29 33 37 %ref5v vsbl max max. voltage for mono 54 58 62 %ref5v vsbl step step resolution 5.0 8.4 12 %ref5v tda7460n 12/31
electrical characteristics (continued) symbol parameter test condition min. typ. max. unit stereoblend and highcut control vhch min min.voltage for no highcut 36 42 46 %ref5v vhch max max. voltage for no highcut 62 66 70 %ref5v vhch step step resolution 5 8.4 12 %ref5v vhcl min min. voltage for full high cut 13 17 21 %vhch vhcl max max. voltage for full high cut 29 33 37 %vhch carrier and harmonic suppression at the output a 19 pilot signal f = 19khz 40 50 db a 38 subcarrier f = 38khz 75 db a 57 subcarrier f = 57khz 62 db a 76 subcarrier f = 76khz 90 db intermodulation (note1) a 2 pilot signal f mod = 10khz; f spur = 1khz; 65 db a 3f mod = 13khz; f spur = 1khz; 75 db traffic radio (note 2) a 57 signal f = 57khz 70 db sca - subsidiary communications authorization (note 3) a 67 signal f = 67khz 75 db aci - adjacent channel interference (note 4) a 114 signal f = 114khz 95 db a 190 signal f = 190khz 84 db notes to the characteristics: 1. intermodulation suppression: measured with: 91% pilot signal; fm = 10khz or 13khz. 2. traffic radio (v.f.) suppression: measured with: 91% stereo signal; 9% pilot signal; fm=1khz; 5% subcarrier (f = 57khz, fm = 23hz am, m = 60%) 3. sca ( subsidiary communications authorization ) measured with: 81% mono signal; 9% pilot signal; fm = 1khz; 10%sca - subcarr ier ( fs = 67khz, unmodulated ). 4. aci ( adjacent channel interference ) measured with: 90% mono signal; 9% pilot signal; fm =1khz; 1% spurious signal ( fs = 110khz or 186khz, unmodulated). 5. by design/characterization but functionally guaranteed through dedicated test mode structure tda7460n 13/31
noise blanker part internal 2nd order 140khz high pass filter programmable trigger threshold additional circuits for trigger adjustment (devia- tion, field-strenght) very low offset current during hold time four selectable pulse suppression times electrical characteristics (continued) symbol parameter test condition min. typ. max. unit v tr trigger threshold 0) 1) meas. with v peak = 0.9v nbt = 111 30 mv op nbt = 110 35 mv op nbt = 101 40 mv op nbt = 100 45 mv op nbt = 011 50 mv op nbt = 010 55 mv op nbt = 001 60 mv op nbt = 000 65 mv op v trnoise noise controlled trigger threshold 2) meas. with v peak = 1.5v nct = 00 260 mv op nct = 01 220 mv op nct = 10 180 mv op nct = 11 140 mv op v rect rectifier voltage v mpx = 0mv 0.5 0.9 1.3 v v mpx = 50mv; f = 150khz 1.5 1.7 2.1 v v mpx = 100mv; f = 150khz 2.2 2.5 2.9 v v rect dev deviation dependent rectifier voltage 3) means. with v mpx = 800mv (75khz dev.) ovd = 11 0.5 0.9(off) 1.3 v op ovd = 10 0.9 1.2 1.5 v op ovd = 01 1.7 2.0 2.3 v op ovd = 00 2.5 2.8 3.1 v op v rect fs fieldstrength controlled rectifier voltage 4) means. with v mpx = 0mv v level << v sbl (fully mono) fsc = 11 0.5 0.9(off) 1.3 v fsc = 10 1.0 1.3 1.6 v fsc = 01 1.5 1.8 2.1 v fsc = 00 2.0 2.3 2.6 v 0) all thresholds are measured using a pulse with t r = 2 m s, t high = 2 m s and t f = 10 m s. 1) nbt represents the noiseblanker-byte bits d2; d0 for the noise blanker trigger threshold 2) nat represents the noiseblanker-byte bit pair d4,d3 for the noise controlled trigger adjustment 3) ovd represents the noiseblanker-byte bit pair d7,d6 for the over deviation detector 4) fsc represents the fieldstrength-byte bit pair d1,d0 for the fieldstrength control v op v in dc t r t high t f time d97au636 tda7460n 14/31
65mv 30mv 8 steps noise controlled trig. threshold min. trig. threshold 260mv(00) 220mv(01) 180mv(10) 140mv(11) 0.9v vth 1.5v v peak(v) d97au648 figure 14. trigger threshold vs. v peak v peak (v op ) d97au649 20 deviation(khz) 0.9 1.2 2.0 2.8 detector off (11) 32.5 45 75 10 01 00 figure 15. deviation controlled trigger adjustment 2.3v(00) 0.9v v peak e' d98au863 1.8v(01) 1.3v(10) mono stereo noisy signal good signal atc_sb off (11) noise ?3v figure 16. fieldstrength controlled trigger adjustment tda7460n 15/31
multipath detector internal 19khz bandpass filter programmable bandpass and rectifier gain two pin solution fully independent usable for external programming selectable internal influence on stereoblend electrical characteristics (continued) symbol parameter test condition min. typ. max. unit f cmp center frequency of multipath- bandpass stereodecoder locked on pilot tone 19 khz g bpmp bandpass gain bits d 2 , d 1 configuration byte = 00 6 db bits d 2 , d 1 configuration byte = 01 16 db bits d 2 , d 1 configuration byte = 10 12 db bits d 2 , d 1 configuration byte = 11 18 db g rectmp rectifier gain bits d 7, d 6 configuration byte = 00 7.6 db bits d 7 , d 6 configuration byte = 01 4.6 db bits d 7 , d 6 configuration byte = 10 0 db i chmp rectifier charge current 1 m a i dismp rectifier discharge current 1.5 ma ingain 3.5 ... 11db step 2.5db infilter lp 80khz 4.th order demodulator - plot canc - roll-off comp. - lp 25khz pll + pilot-det. f19 noise blanker f38 stereo holdn sb control deemphasis + highcut t=50 or 75 m s ref 5v vsbl mpinfl level intern hc control vhcch vhccl - multipath detector d a mpout level input lp 2.2khz 1.th order mpin level fm_l fm_r mpx 100k d97au762 gain 0..10db figure 17. block diagram of the stereodecoder tda7460n 16/31
description of stereodecoder the stereodecoder part of the tda7460n (see fig. 17) contains all functions necessary to de- modulate the mpx signal like pilot tone depend- ent mono/stereo switching as well as "stereoblend" and "highcut" functions. adaptations like programmable input gain, roll-off compensation, selectable deemphasis time con- stant and a programmable fieldstrength input al- low to use different if devices. stereodecoder mute the tda7460n has a fast and easy to control rds mute function which is a combination of the audioprocessor softmute and the high-ohmic mute of the stereodecoder. if the stereodecoder is selected and a softmute command is sent (or activated through the sm pin) the stereodecoder will be set automatically to the high-ohmic mute condition after the audio signal has been soft- muted. hence a checking of alternate frequencies could be performed. to release the system from the mute condition simply the unmute command must be sent: the stereodecoder is unmuted immedi- ately and the audioprocessor is softly unmuted. fig. 18 shows the output signal v o as well as the internal stereodecoder mute signal. this influ- ence of softmute on the stereodecoder mute can be switched off by setting bit 3 of the softmute byte to "0". a stereodecoder mute command (bit 0, stereodecoder byte set to "1") will set the stereodecoder in any case independently to the high-ohmic mute state. if any other source than the stereodecoder is se- lected the decoder remains muted and the mpx pin is connected to vref to avoid any discharge of the coupling capacitor through leakage currents. input stages the ingain stage allows to adjust the mpx signal to a magnitude of about 1vrms internally which is the recommended value. the 4.th order input fil- ter has a corner frequency of 80khz and is used to attenuate spikes and noise and acts as an anti- aliasing filter for the following switch capacitor fil- ters. demodulator in the demodulator block the left and the right channel are separated from the mpx signal. in this stage also the 19 khz pilot tone is cancelled. for reaching a high channel separation the tda7460n offers an i2c bus programmable roll- off adjustment which is able to compensate the lowpass behaviour of the tuner section. if the tuner attenuation at 38khz is in a range from 20.2% to 31% the tda7460n needs no external network before the mpx pin. within this range an adjustment to obtain at least 40db channel sepa- ration is possible. the bits for this adjustment are located together with the fieldstrength adjustment in one byte. this gives the possibility to perform an optimization step during the production of the carradio where the channel separation and the fieldstrength con- trol are trimmed. deemphasis and highcut. the lowpass filter for the deemphasis allows to choose between a time constant of 50 m s and 75 m s (bit d7, stereodecoder byte). the highcut control range will be in both cases t hc = 2 t deemp . inside the highcut control range (between vhch and vhcl) the level signal is converted into a 5 bit word which controls the lowpass time constant between t deemp ...3 t deemp . there by the resolution will remain always 5 bits independently of the absolute voltage range be- tween the vhch and vhcl values. the highcut function can be switched off by i2c bus (bit d7, fieldstrength byte set to "0"). pll and pilot tone detector the pll has the task to lock on the 19khz pilo- tone during a stereo transmission to allow a cor- rect demodulation. the included detector enables the demodulation if the pilot tone reaches the se- lected pilottone threshold vpthst. two different thresholds are available. the detector output (sig- nal stereo, see block diagram) can be checked softmute command std mute v o t d97au638 t t figure 18. signals during stereodecoders softmute tda7460n 17/31
by reading the status byte of the tda7460n via i2c bus. fieldstrength control the fieldstrength input is used to control the high cut and the stereoblend function. in addition the signal can be also used to control the noise- blanker thresholds. level input and gain to suppress undesired high frequency modula- tion on the highcut and stereoblend function the level signal is lowpass filtered firstly. the filter is a combination of a 1st order rc lowpass at 53khz (working as anti-aliasing filter) and a 1st- order switched capacitor lowpass at 2.2khz. the second stage is a programmable gain stage to adapt the level signal internally to different if. the gain is widely programmable in 16 steps from 0db to 10db (step = 0.67db). these 4 bits are located together with the roll-off bits in the "stereodecoder adjustment" byte to simplify a possible adaptation during the production of the carradio. stereoblend control the stereoblend control block converts the inter- nal level voltage (level intern) into an de- modulator compatible analog signal which is used to control the channel separation between 0db and the maximum separation. internally this con- trol range has a fixed upper limit which is the in- ternal reference voltage ref5v. the lower limit can be programmed to be 33%, 42%, 50% or 58% of ref5v (see fig. 20). to adjust the external level voltage to the inter- nal range two values must be defined: the level gain l g and vsbl. to adjust the voltage where the full channel separation is reached (vst) the level gain l g has to be defined. the following equation can be used to estimate the gain: l g = ref5v field strength voltage [stereo] the gain can be programmed through 4 bits in the "stereodecoder-adjustment" byte. the mono voltage vmo (0db channel separa- tion) can be choosen selecting 33, 42, 50 or 58% of ref5v. all necessary internal reference voltages like ref5v are derived from a bandgap circuit. therefore they have a temperature coefficient near zero. this is useful if the fieldstrength signal is also temperature compensated. but most if devices apply a level voltage with a tc of 3300ppm. the tda7460n offers this tc for the reference voltages, too. the tc is select- able with bit d7 of the "stereodecoder adjust- ment" byte. figure 19. internal stereoblend characteristics internal voltages t d97au639 vsbl ref 5v setup of vst internal voltages t 33% ref 5v setup of vmo level level intern fieldstrenght voltage vst vmo level intern 42% 50% 58% vsbl vst vmo fieldstrenght voltage figure 20. relation between internal and external level voltage and setup of stereoblend tda7460n 18/31
highcut control the highcut control setup is similar to the stereoblend control setup : the starting point vhch can be set with 2 bits to be 42, 50, 58 or 66% of ref5v whereas the range can be set to be 17 or 33% of vhch (see fig. 21). functional description of the noise- blanker in the automotive environment the mpx signal is disturbed by spikes produced by the ignition and for example the wiper motor. the aim of the noiseblanker part is to cancel the audible influ- ence of the spikes. therefore the output of the stereodecoder is held at the actual voltage for 40 m s. in a first stage the spikes must be detected but to avoid a wrong triggering on high frequency (white) noise a complex trigger control is imple- mented. behind the triggerstage a pulse former generates the "blanking" pulse. to avoid any crosstalk to the signalpath the noiseblanker is supplied by his own biasing circuit. trigger path the incoming mpx signal is highpass filtered, amplified and rectified. this second order high- pass-filter has a corner frequency of 140khz. the rectified signal, rect, is lowpass filtered to gen- erate a signal called peak. also noise with a fre- quency 140khz increases the peak voltage. the peak voltage is fed to a threshold generator, which adds to the peak voltage a dc depend- ent threshold vth. both signals, rect and peak+vth are fed to a comparator which trig- gers a re-triggerable monoflop. the monoflops output activates the sample-and-hold circuits in the signalpath for 40 m s. the block diagram of the noiseblanker is given in fig.22. automatic noise controlled threshold adjust- ment (atc) there are mainly two independent possibilities for programming the trigger threshold: a the low threshold in 8 steps (bits d0 to d2 of the noiseblanker byte) b the noise adjusted threshold in 4 steps (bits d3 and d4 of the noiseblanker byte, see fig. 14). the low threshold is active in combination with a good mpx signal without any noise; the peak voltage is less than 1v. the sensitivity in this op- eration is high. if the mpx signal is noisy the peak voltage in- creases due to the higher noise, which is also rectified. with increasing of the peak voltage the trigger threshold increases, too. this particular gain is programmable in 4 steps (see fig. 14). lowpass time constant d97au640 t deemp fieldstrenght vhch vhcl 3 t deemp figure 21. highcut characteristics + - rectifier lowpass rect + + threshold generator vth peak additional threshold control monoflop holdn mpx d98au861 high pass figure 22. block diagram of the noiseblanker tda7460n 19/31
automatic threshold control besides the noise controlled threshold adjust- ment there is an additional possibility for influenc- ing the trigger threshold. it is depending on the stereoblend control. the point where the mpx signal starts to become noisy is fixed by the rf part. therefore also the starting point of the normal noise-controlled trig- ger adjustment is fixed (fig. 16). in some cases the behaviour of the noiseblanker can be im- proved by increasing the threshold even in a re- gion of higher fieldstrength. sometimes a wrong triggering occures for the mpx signal often shows distortion in this range which can be avoided even if using a low threshold. because of the overlap of this range and the range of the stereo/mono transition it can be con- trolled by stereoblend. this threshold increase is programmable in 3 steps or switched off with bits d0 and d1 of the fieldstrength control byte. over deviation detector if the system is tuned to stations with a high de- viation the noiseblanker can trigger on the higher frequencies of the modulation. to avoid this wrong behaviour, which causes noise in the out- put signal, the noiseblanker offers a deviation de- pendent threshold adjustment. by rectifying the mpx signal a further signal rep- resenting the actual deviation is obtained. it is used to increase the peak voltage. offset and gain of this circuit are programmable in 3 steps with the bits d6 and d7 of the stereodecoder byte (the first step turns off the detector, see fig. 15). functional description of the multi- path detector using the internal detector the audible effects of a multipath condition can be minimized. a multipath condition is detected by rectifying the 19khz spectrum in the fieldstrength signal. selecting the "internal influence" in the configura- tion byte, the channel separation is automatically reduced during a multipath condition according to the voltage appearing at the mpout pin. to obtain a optimal performance an adaptation is necessary. therefore the gain of the 19khz band- pass is programmable in four steps as well as the rectifier gain. the attack and decay times can be set by the external capacitor value. test mode during the test mode which can be activated by setting bit d0 of the testing byte and bit d5 of the subaddress byte to "1" several internal signals are available at the cassr pin. during this mode the input resistance of 100kohm is discon- nected from the pin. the internal signals available are shown in the software specification. rectifier bandpass 19khz - to sb mp enable d98au862 mpin gain 2 bits gain 2 bits dc=1 m vdd 15k mpout to phone_gnd - apr level int. influence 220nf figure 23. block diagram of the multipath detector tda7460n 20/31
= +v cc 9v 100nf cass r cass l 100nf 100nf cdr cdg 100nf 22 m f cdl 100nf phone_gnd 220nf cass r cass l cdr cdg cdl phgnd phone 220nf phone outrr mpx 220nf outrr mpx am 220nf am outlr outlr outrf outrf outlf outlf cref 10 m f d97au643a level smute scl sda level smute scl sda gnd v s tda7460 figure 24. application example 1 (with phone input) = +v cc 9v 100nf cass r cass l 100nf 100nf cdr cdg 100nf 22 m f cdl 100nf cass r cass l cdr cdg cdl outrr mpx 220nf outrr mpx am 220nf am outlr outlr outrf outrf outlf outlf cref 10 m f d97au645a level smute scl sda level smute scl sda gnd v s tda7460 unweighted level mpin mpout 47nf figure 25. application example 2 (with multipath) tda7460n 21/31
i 2 c bus interface description interface protocol the interface protocol comprises: -a start condition (s) -a chip address byte (the lsb bit determines read / write transmission) -a subaddress byte -a sequence of data (n-bytes + acknowledge) -a stop condition (p) d97au627 s 1 0 0 0 1 1 0 r/w ack ack ack p msb lsb msb lsb msb lsb chip address xi subaddress data 1 to data n az t a3 a2 a1 a0 data s = start ack = acknowledge az = autozero-remain t = testing i = autoincrement p = stop max clock speed 500kbits/s the transmitted data is automatically updated af- ter each ack. transmission can be repeated without new chip address. auto increment if bit i in the subaddress byte is set to "1", the autoincrement of the subaddress is enabled. transmitted data (send mode) msb lsb xxxxstsmxx sm = soft mute activated st = stereo x = not used subaddress (receive mode) msb lsb function x az t i a3a2a1a0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 input selector loudness / auto-zero volume softmute / beep bass / treble attenuator bass / treble configuration speaker attenuator lf speaker attenuator lr speaker attenuator rf speaker attenuator rr / blanktime adjust stereodecoder noiseblanker fieldstrength control configuration stereodecoder adjustment testing t = testmode i = autoincrement az = auto zero remain x = not used tda7460n 22/31
data byte specification input selector msb lsb function d7 d6 d5 d4 d3 d2 d1 d0 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 source selector cd cassette phone am stereo decoder input fm mute ac inputs 0 1 cd mode cd full-differential cd quasi-diff 1 0 0 1 0 0 1 1 1 1 0 0 1 1 0 0 am/fm mode am mono am stereo am through stereodecoder fm- stereodecoder 0 0 : 1 1 0 0 : 1 1 0 1 : 0 1 in-gain 14db 12db : 2 db 0 db for example to select the cd input in quasi-differential mode with gain of 8db the data byte is: 0/01111000 loudness msb lsb loudness d7 d6 d5 d4 d3 d2 d1 d0 0 0 : 1 1 0 0 : 1 1 0 0 : 1 1 0 1 : 0 1 attenuation 0db -1db : -14db -15db 0 1 filter on off (flat) 0 1 center frequency 200hz 400hz 0 1 loudness q low (1 st order) normal (2 nd order) 1 must be "1" note: the attenuation is specified at high frequencies. around the center frequency the value is different depending on the pro grammed attenuation (see loudness frequency response). tda7460n 23/31
mute, beep and mixing msb lsb mute/beep/mixing d7 d6 d5 d4 d3 d2 d1 d0 0 1 0 0 1 1 0 1 0 1 0 1 mute enable softmute disable softmute mute time =0.48 ms mute time =0.96 ms mute time =40.4 ms mute time =324 ms stereo decoder softmute influence = off stereo decoder softmute influence = on 0 1 beep beep frequency = 600hz beep frequency = 1.2khz 0 0 1 1 0 1 0 1 0 1 mixing mix-source = beep mix-source = phone full mix signal source -12db + mix-signal -2.5db source -6db + mix-signal -6db full source note: for more information to the stereodecoder-softmute-influence please refer to the stereodecoder description. volume msb lsb attenuation d7 d6 d5 d4 d3 d2 d1 d0 0 0 : 0 0 0 : 0 0 0 : 1 1 0 0 : 0 0 0 : 0 1 1 : 1 1 0 0 : 0 0 0 : 1 0 0 : 0 0 0 0 : 1 1 1 : 1 0 0 : 1 1 0 0 : 1 1 1 : 1 0 0 : 1 1 0 0 : 0 0 1 : 1 0 0 : 1 1 0 1 : 0 1 0 : 1 0 1 : 0 1 gain/attenuation +32db +31db : +20db +19db +18db : +1db 0db - 1db : -78db -79db 0 1 softstep softstep volume = off softstep volume = on note: it is not recommended to use a gain more than 20db for system performance reason. in general, the max. gain should be lim ited by software to the maximum value, which is needed for the system. tda7460n 24/31
bass & treble attenuation msb lsb bass & treble attenuation d7 d6 d5 d4 d3 d2 d1 d0 0 0 : 0 0 1 1 : 1 1 0 0 : 1 1 1 1 : 0 0 0 0 : 1 1 1 1 : 0 0 0 1 : 0 1 1 0 : 1 0 treble steps -14db -12db : -2db 0db 0db +2db : +12db +14db 0 0 : 0 0 1 1 : 1 1 0 0 : 1 1 1 1 : 0 0 0 0 : 1 1 1 1 : 0 0 0 1 : 0 1 1 0 : 1 0 bass steps -14db -12db : -2db 0db 0db +2db : +12db +14db for example 12db treble and -8db bass give the following data byte : 0 0 1 1 1 0 0 1. bass & treble filter characteristics msb lsb bass & treble filter d7 d6 d5 d4 d3 d2 d1 d0 0 0 1 1 0 1 0 1 treble center frequency = 10 khz center frequency = 12.5 khz center frequency = 15 khz center frequency = 17.5 khz 0 1 1 0 0 1 1 1 0 1 0 1 0 0 1 1 1 0 1 0 1 1 bass center frequency = 60 hz center frequency = 70 hz center frequency = 80 hz center frequency = 100hz center frequency = 150hz quality factor = 1 quality factor = 1.25 quality factor = 1.5 quality factor = 2 dc-gain = 0db dc-gain = 4.4db 1 must be "1" for example treble center frequency = 15khz, bass center frequency = 100hz, bass q = 1 and dc = 0db give the following data byt e: 1 0 0 0 1 1 1 0 tda7460n 25/31
speaker attenuation (lf, lr, rf, rr) msb lsb d7 d6 d5 d4 d3 d2 d1 d0 11 0 0 : 0 0 0 0 0 0 0 0 0 1 0 0 : 1 1 1 1 1 1 1 1 1 0 0 : 0 1 1 1 1 1 1 1 1 0 0 : 1 0 0 0 0 1 1 1 1 0 0 : 1 0 0 1 1 0 0 1 1 0 1 : 1 0 1 0 1 0 1 0 1 attenuation 0db -1db : -23db -24.5db -26db -28db -30 -32db -35db -40db -50db speaker mute must be "1" (except rr speaker; see below) 0 0 1 1 0 1 0 1 blank time adj. (only at rr speaker) 38 m s 25.5 m s 32 m s 22 m s tda7460n 26/31
stereodecoder msb lsb function d7 d6 d5 d4 d3 d2 d1 d0 0 1 std unmuted std muted 0 0 1 1 0 1 0 1 in-gain 11db in-gain 8.5db in-gain 6db in-gain 3.5db 1 must be "1" 1 1 0 1 forced mono mono/stereo switch automatically 0 1 pilot threshold high pilot threshold low 0 1 deemphasis 50 m s deemphasis 75 m s noiseblanker msb lsb function d7 d6 d5 d4 d3 d2 d1 d0 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 low threshold 65mv low threshold 60mv low threshold 55mv low threshold 50mv low threshold 45mv low threshold 40mv low threshold 35mv low threshold 30mv 0 0 1 1 0 1 0 1 noise controlled threshold 320mv noise controlled threshold 260mv noise controlled threshold 200mv noise controlled threshold 140mv 0 1 noise blanker off noise blanker on 0 0 1 1 0 1 0 1 over deviation adjust 2.8v over deviation adjust 2.0v over deviation adjust 1.2v over deviation detector off tda7460n 27/31
configuration msb lsb function d7 d6 d5 d4 d3 d2 d1 d0 0 0 1 1 0 1 0 1 noise rectifier discharge resistor r = infinite r = 56k w r = 33k w r =18k w 0 0 1 1 0 1 0 1 multipath detector bandpass gain 6db 16db 12db 18db 0 1 multipath detector internal influence on off 0 1 multipath/function selected (mpin, mpout) additional input selected (phone) 0 0 1 1 0 1 0 1 multipath detector reflection gain gain = 7.6db gain = 4.6db gain = 0db off fieldstrength control msb lsb function d7 d6 d5 d4 d3 d2 d1 d0 0 0 1 1 0 1 0 1 noiseblanker field strength adj 2.3v noiseblanker field strength adj 1.8v noiseblanker field strength adj 1.3v noiseblanker field strength adj off 0 0 1 1 0 1 0 1 vsbl at 33% ref 5v vsbl at 42% ref 5v vsbl at 50% ref 5v vsbl at 58% ref 5v 0 0 1 1 0 1 0 1 vhch at 42% ref 5v vhch at 50% ref 5v vhch at 58% ref 5v vhch at 66% ref 5v 1 0 vhcl at 17% vhch vhcl at 33% vhch 0 1 high cut off high cut on tda7460n 28/31
stereodecoder adjustment msb lsb function d7 d6 d5 d4 d3 d2 d1 d0 0 0 0 : 1 : 1 0 0 1 : 0 : 1 0 1 0 : 0 : 1 roll-off compensation not allowed 20.2% 21.9% : 25.5% : 31.0% 0 0 0 : 1 0 0 0 : 1 0 0 1 : 1 0 1 0 : 1 level gain 0db 0.66db 1.33db : 10db 0 1 temperature compensation at level input tc = 0 tc = 16.7mv/k (3300ppm) testing msb lsb function d7 d6 d5 d4 d3 d2 d1 d0 0 1 stereodecoder test signals off test signals enabled if bit d5 of the subaddress (test mode bit) is set to "1", too 0 1 external clock internal clock 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 testsignals at cass_r vhcch level intern pilot magnitude vcocon; vco control voltage pilot threshold holdn nb threshold f228 vhccl vsbl not used not used peak not used ref5v not used 0 1 vco off on 0 1 audioprocessor test mode only if bit d5 of the subaddress (test mode bit) is set to "1" off note : this byte is used for testing or evaluation purposes only and must not be set to other values than the default "11111110 " in the application! tda7460n 29/31
11 0 11 20 a e b d e l k h a1 c so20mec h x 45? so20 dim. mm inch min. typ. max. min. typ. max. a 2.35 2.65 0.093 0.104 a1 0.1 0.3 0.004 0.012 b 0.33 0.51 0.013 0.020 c 0.23 0.32 0.009 0.013 d 12.6 13 0.496 0.512 e 7.4 7.6 0.291 0.299 e 1.27 0.050 h 10 10.65 0.394 0.419 h 0.25 0.75 0.010 0.030 l 0.4 1.27 0.016 0.050 k 0? (min.)8? (max.) outline and mechanical data tda7460n 30/31
information furnished is believed to be accurate and reliable. however, stmicroelectronics assumes no responsibility for the co nsequences 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 pu blication are subject to change without notice. this publication supersedes and replaces all information previously supplied. stmicroelectron ics products are not authorized for use as critical components in life support devices or systems without express written approval of stmicr oelectronics. the st logo is a registered trademark of stmicroelectronics ? 2000 stmicroelectronics C printed in italy C all rights reserved stmicroelectronics group of companies australia - brazil - china - finland - france - germany - hong kong - india - italy - japan - malaysia - malta - morocco - singapore - spain - sweden - switzerland - united kingdom - u.s.a. http://www.st.com tda7460n 31/31

▲Up To Search▲

Price & Availability of TDA7460NDTR

	To Download TDA7460NDTR Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .