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may 2009 doc id 8120 rev 7 1/31 31 TSH512 hi-fi stereo/mono infrared transmitter and stereo sub-carrier generator features supply voltage: 2.3 to 5.5 v carrier frequency range: 0.4 to 11 mhz high versatility: i/o pi ns for each section two fm transmitters for stereo sinusoidal carriers for high spectral purity micro- or line-level preamplifiers with alc vox function to save on battery power transmitter tx2 standby for mono operation applications infrared hi-fi stereo transmitters infrared headsets stereo sub-carriers for video transmitters voice-operated wireless webcams fm if transmit systems description the TSH512 is a 0.4- to 11-mhz dual fm transmitter. access pins to each section give high versatility and allow for several different applications: stereo headphone, multimedia headset, audio sub-carrier generator. the TSH512 integrates in a single chip low-noise audio preamplifiers with alc (automatic level control), frequency-modu lated oscillators, and linear output buffers to drive the external transistors. the sinusoidal carriers facilitate the filtering and allow high performance audio transmission. the vox (voice operated transmit) circuitry disables the output buffer when there is no audio signal to save battery power. for mono applications, the standby pin enables one transmitter only, reducing the supply current. the TSH512 forms a chipset with the dual receiver tsh511. 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 1 + -+ - + - + - t s h512 mono s table alc alc vco vco output buffer output buffer tx1 tx2 lna lna vox - + pea pea 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 1 - -+ - + - + t s h512 mono s table alc alc vco vco output buffer output buffer tx1 tx2 lna lna vox - + pea pea pin connections (top view) f tqfp44 10 x 10 mm www.st.com
contents TSH512 2/31 doc id 8120 rev 7 contents 1 absolute maximum rating s and operating condi tions . . . . . . . . . . . . . 3 2 device diagrams and sc hematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.1 supply section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.2 audio section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.3 rf section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4 application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.1 infrared stereo transmitter application (stereo headphones) . . . . . . . . . . 14 4.2 sub-carrier generator application: voice-operated wireless camera . . . . 16 4.3 multimedia application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 4.3.1 headset side . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 4.3.2 computer side . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 5 general description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8 5.1 lna section: low noise amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 5.2 electret condenser microphone source . . . . . . . . . . . . . . . . . . . . . . . . . . 19 5.3 mic-bias section: microphone bias voltage . . . . . . . . . . . . . . . . . . . . . . 20 5.4 alc section: automatic level control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 5.5 vox description: voice operated transmit . . . . . . . . . . . . . . . . . . . . . . . . 21 5.6 pea section: pre-emphasis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 5.7 vco section: voltage-controlled oscillator . . . . . . . . . . . . . . . . . . . . . . . . 25 5.8 output buffer section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 5.9 sby pin: standby for mono operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 6 package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 6.1 tqfp44 package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 7 ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 8 revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 0
TSH512 absolute maximum rati ngs and operating conditions doc id 8120 rev 7 3/31 1 absolute maximum ratings and operating conditions table 1. absolute maximum ratings symbol parameter value unit v cc supply voltage (1) 1. all voltage values, except differential voltage, are with respect to network ground terminal. 7v t oper operating free air temperature range -40 to +85 c t stg storage temperature -65 to +150 c t j maximum junction temperature 150 c r thjc thermal resistance j unction to case 14 c/w r thja thermal resistance junction to ambient area 45 c/w latch-up class (2) 2. corporate st microelectr onics procedure number 0018695. a esd sensitive device: handling precautions required esd except pins 20 and 36 hbm: human body model (3) cdm: charged device model (4) mm: machine model (5) 3. human body model: a 100 pf capacit or is charged to the specified voltage, then discharged through a 1.5 k resistor between two pins of the device. this is done for all couples of connected pin combinations while the other pins are floating. 4. charged device model: all pins and the package are charged together to the specified voltage and then discharged directly to the ground through only one pin. th is is done for all pins. 5. machine model: a 200 pf capacitor is charged to the specified voltage, then discharged directly between two pins of the device with no external series resistor (internal resistor < 5 ). this is done for all couples of connected pin combinations whil e the other pins are floating. 2 1 0.2 kv table 2. operating conditions symbol parameter value unit v cc supply voltage 2.3 to 5.5 v f audio audio frequency range 20 to 20,000 hz f carrier carrier frequency range 0.4 to 11 mhz
device diagrams and schematics TSH512 4/31 doc id 8120 rev 7 2 device diagrams and schematics this section contains a detailed block diagram of the TSH512 ( figure 1 ), with an accompanying pin description ( table 3 on page 5 ), as well as the schematics of a typical application ( figure 2 on page 6 ). figure 1. block diagram 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 1 + -+ - + - + - t s h512 mono s table alc alc vco vco output buffer output buffer tx1 tx2 lna lna vox - + pea pea 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 1 - -+ - + - + t s h512 mono s table alc alc vco vco output buffer output buffer tx1 tx2 lna lna vox - + pea pea vco-bia s 2 vco-out2 lna-inp2 lna-inn2 lna-out2 alc-int2 pea-inn2 pea-out2 vcc vco-a2 vco-b2 vco-bia s 2 vco-out2 lna-inp2 lna-inn2 lna-out2 alc-int2 pea-inn2 pea-out2 vcc vco-a2 vco-b2 dec2 mic-bia s 2 gnd vcc s by vox-int s vox- s en s vcc gnd mic-bia s 1 dec1 dec2 mic-bia s 2 gnd vcc s by vox-int s vox- s en s vcc gnd mic-bia s 1 dec1 gnd buf-in2 buf-out2 gnd vox-timer vox-intn vox-mute vcc buf-out1 buf-in1 gnd gnd buf-in2 buf-out2 gnd vox-timer vox-intn vox-mute vcc buf-out1 buf-in1 gnd lna-inp1 lna-inn1 lna-out1 alc-int1 pea-inn1 pea-out1 vco-bia s 1 vcc vco-a1 vco-b1 vco-out1 lna-inp1 lna-inn1 lna-out1 alc-int1 pea-inn1 pea-out1 vco-bia s 1 vcc vco-a1 vco-b1 vco-out1
TSH512 device diagrams and schematics doc id 8120 rev 7 5/31 table 3 . pin descriptions pin pin name related to direction (1) pin description 1 dec2 tx2 - decoupling capacitor for internal voltage reference 2 mic-bias2 tx2 o microphone bias 3 gnd - - ground 4 vcc - - supply voltage 5 sby tx1 & tx2 i standby control (input pin) 6 vox-ints tx1 & tx2 - time constant terminal for audio signal integrator in vox 7 vox-sens tx1 & tx2 - gain adjustment for vox input sensitivity 8 vcc - - supply voltage 9 gnd - - ground 10 mic-bias1 tx1 o microphone bias 11 dec1 tx1 - decoupling capacitor for internal voltage reference 12 lna-inp1 tx1 i lna positive input 13 lna-inn1 tx1 i lna negative input 14 lna-out1 tx1 o lna output 15 alc-int1 tx1 - time constant te rminal for integrator in alc 16 pea-inn1 tx1 i pre-emphasis amplifier negative input 17 pea-out1 tx1 o pre-emp hasis amplifier output 18 vco-bias1 tx1 o bias for external vco components 19 vcc - - supply voltage 20 vco-a1 tx1 - oscillator component connection 21 vco-b1 tx1 - oscillator component connection 22 vco-out1 tx1 o vco output 23 gnd - - ground 24 buf-in1 tx1 i input to the output buffer 25 buf-out1 tx1 o output of the output buffer 26 vcc - - supply voltage 27 vox-mute tx1 & tx2 o mute co ntrol (output pin) in vox 28 vox-intn tx1 & tx2 - time constant terminal for noise integrator in vox 29 vox-timer tx1 & tx2 - rise time for timer in vox 30 gnd - - ground 31 buf-out2 tx2 o output of the output buffer 32 buf-in2 tx2 i input to the output buffer 33 gnd - - ground 34 vco-out2 tx2 o vco output 35 vco-b2 tx2 - oscillator component connection
device diagrams and schematics TSH512 6/31 doc id 8120 rev 7 figure 2. typical application schematics for stereo infrared transmitter 36 vco-a2 tx2 - oscillator component connection 37 vcc - - supply voltage 38 vco-bias2 tx2 o bias for external vco components 39 pea-out2 tx2 o pre-emphas is amplifier output 40 pea-inn2 tx2 i pre-emphasis amplifier negative input 41 alc-int2 tx2 - time constant terminal for internal peak detector in alc 42 lna-out2 tx2 o lna output 43 lna-inn2 tx2 i lna negative input 44 lna-inp2 tx2 i lna positive input 1. pin directions: i = input pin, o = output pin, - = pin to connect to supply or decoupling capacitors or external components. table 3 . pin descriptions (continued) pin pin name related to direction (1) pin description
TSH512 electrical characteristics doc id 8120 rev 7 7/31 3 electrical characteristics table 4. electrical characteristics for v cc = 2.7 v, t amb = 25 c, f audio = 1 khz, f carrier = 2. 8 mhz (unless otherwise specified) (1) symbol parameter test conditions min. typ. max. unit overall circuit i cc_tot current consumption tx1 and tx2 are on tx1 on, tx2 on, mic-bias1 and mic-bias2 not used: vox-mute=1 output buffers on vox-mute=0, output buffers off 16 11 18.6 12.8 ma -40 c < t amb <+85c vox-mute=1 output buffers on vox-mute=0, output buffers off 19.6 13.8 i cc_sby current consumption with tx2 in standby: sby (pin5) active tx1 on, tx2 off, mic-bias1 and mic-bias2 not used: vox-mute=1,output buffers on vox-mute=0, output buffers off 10 7 11.5 8 ma -40 c < t amb <+85c vox-mute=1, output buffers on vox-mute=0, output buffers off 12.1 8.6 lna sections (for tx1 and tx2) gbp lna gain bandwidth product no external load 7 mhz rin lna input resistance on positive input: (lna-inp1 pin 12 or lna-inp2 pin 44) 30 k thd lna total harmonic distortion g lna =0db, vout lna = 700 mv pp 0.01 0.05 % -40 c < t amb < +85 c 0.05 en equivalent input noise voltage g lna =40db, at f=1khz r s =390 , r feedback =39k 6nv/ hz automatic level control (alc) section g alc voltage gain 20 db v alc_out regulated output level (at positive input of the pea amplifier) 600 710 800 mvpp -40 c < t amb < +85 c 597 803 pre-emphasis amplifier (pea) section gbp pea gain bandwidth product (pea-out1 pin 17 or pea-out2 pin 39) no load 9 mhz v opp-pea output voltage r l = 22 k 550 mvpp
electrical characteristics TSH512 8/31 doc id 8120 rev 7 audio lna+alc+pea sections thd alc total harmonic distortion in linear region on pea-out1 pin17 or pea-out2 pin 39 g lna = 0 db, f = 1 khz (v in)alc < 25 mv rms (-30 dbu) r l = 22 k tied to gnd 0.05 0.15 % -40 c < t amb < +85 c 0.25 thd agc total harmonic distortion in compression region (v in ) alc = 36 mv rms (-27 dbu) (v in ) alc = 100 mv rms (-18 dbu) r l = 22 k tied to gnd 1.3 3 1.7 4 % -40 c < t amb <+85c (v in ) alc = 36 mv rms (-27 dbu) (v in ) alc = 100 mv rms (-18 dbu) 2.5 5.3 ? pea phase margin at pea-out1 pin 17 or pea-out2 pin 39 r l =22k lna and pea at unity gain v in = 40 mv 70 microphone biasing section v mic-bias microphone biasing voltage ( section 5.3 on page 20 ) i mic-bias = 2.5 ma 2.15 2.25 2.35 v -40 c < t amb < +85 c 2.14 2.36 v mic-bias v mic-bias temperature coefficient over temp. range: [0, 70 c] [-40, 85 c] i mic-bias = 2.5 ma 260 460 ppm/c i mic-bias mic-bias current capability over v cc range [2.3 v?5.5 v] 2.5 ma psrr mic-bias power supply rejection ratio of mic-bias at 1 khz and v ripple = 25 mv rms 50 db en mic-bias equivalent input noise of mic-bias v cc =2.7v v cc =5.0v 22 42 nv/ hz vox operated switch (vox) section i vox-timer monostable current source (vox-timer pin 29) v cc = 2.7v 5 a vth vox-timer threshold voltage of the monostable (time constant) 1.4 v v mute_l low level output voltage (vox-mute pin 27) r l = 2 k 0.2 v -40 c < t amb <+85c 0.2 v mute_h high level output voltage (vox-mute pin 27) r l = 2 k v cc -0.3 v -40 c < t amb <+85c v cc - 0.32 table 4. electrical characteristics for v cc = 2.7 v, t amb = 25 c, f audio = 1 khz, f carrier = 2. 8 mhz (unless otherwise specified) (continued) (1) symbol parameter test conditions min. typ. max. unit
TSH512 electrical characteristics doc id 8120 rev 7 9/31 standby v sby_il maximum maximum low level input voltage of standby input (sby pin 5) 0.1xv cc v v sby_ih minimum minimum high level input voltage of standby input (sby pin 5) 0.9xv cc v vco section v vco-bias vco-bias output voltage (vco-bias1 pin 18 or vco-bias2 pin 38) with no load 1.43 1.47 1.51 v dc -40 c < t amb < +85 c 1.38 1.56 i vco-bias vco-bias output current capability v vco-bias > 1.38 v 40 a v vco-bias vco-bias voltage drift 2.3 v < v cc < 5.5 v [0, 70 c] v cc =2.7v [0, 70 c] v cc =5.0v [-40, 85 c] v cc =2.7v [-40, 85 c] v cc =5.0v 8 +265 +356 +265 +356 mv/v ppm/c ppm/c ppm/c ppm/c pn lo phase noise at 1 khz, l = 120 h (q = 30) and r vco not connected -80 dbc svr vco-bias supply voltage rejection ratio of vco-bias with no load 43 db z vco-out vco output impedance (vco-out1 pin 22 or vco-out2 pin 34) 400 zl vco-out minimum minimum load impedance 1 k v vco-out vco output level l= 120h (q=30) vco output connec ted to output buffer input r vco = 100 k 580 620 660 mvpp -40 c < t amb < +85 c 569 671 output buffer z buf-in input impedance (buf-in1 pin 24 or buf-in2 pin 32) 400 k g ob linear voltage gain 10 db v buf-out ac output ac voltage at 1db compression point z l =2k 1.3 vpp output ac voltage (buf-out1 pin 25 or buf-out2 pin 31) z l =2k v buf-in = 0.60 vpp 1.35 1.5 1.7 -40 c < t amb < +85 c 1.33 1.72 table 4. electrical characteristics for v cc = 2.7 v, t amb = 25 c, f audio = 1 khz, f carrier = 2. 8 mhz (unless otherwise specified) (continued) (1) symbol parameter test conditions min. typ. max. unit
electrical characteristics TSH512 10/31 doc id 8120 rev 7 3 .1 supply section 3 .2 audio section v buf-out dc output dc voltage dc output current = 0.4 ma 1.25 v dc h2 buf-out 2nd harmonic level v buf-out = 1.2 v pp and z l =2k -40 dbc h3 buf-out 3rd harmonic level v buf-out =1.2v pp and z l =2k -30 dbc 1. limits over -40 c < tamb < +85 c range are guaranteed by stat istical correlation. figure 3 . supply current vs. supply voltage table 4. electrical characteristics for v cc = 2.7 v, t amb = 25 c, f audio = 1 khz, f carrier = 2. 8 mhz (unless otherwise specified) (continued) (1) symbol parameter test conditions min. typ. max. unit 0123456 0 2 4 6 8 10 12 14 16 18 tx1 tx1+buffers tx1+tx2 tx1+tx2+buffers i cc (ma) v cc (v) figure 4. lna distortion vs. frequency figure 5. lna distortion vs. lna output voltage 10 100 1000 10000 0.01 0.1 1 v cc = 2.7v g lna = 0db v out-lna = 700mv pp thd lna +n (%) frequency (hz) 0 200 400 600 800 1000 1200 1400 1600 1e-3 0.01 0.1 1 10 100 g lna = 0db v cc = 5.5v v cc = 2.7v v cc = 2.3v thd lna +n (%) v out-lna (mv pp )
TSH512 electrical characteristics doc id 8120 rev 7 11/31 figure 6. supply current vs. temperature figure 7. lna distortion vs. frequency 020406080 0 2 4 6 8 10 12 14 16 v cc = 2.7v tx1+tx2 tx1 tx1+buffers tx1+tx2+buffers i cc (ma) t amb (c) 10 100 1000 10000 0.1 1 10 v cc = 2.7v g lna = 40db v out-lna = 700mv pp thd lna +n (%) frequency (hz) figure 8 . pea output voltage vs. lna input voltage figure 9. pea output voltage vs. temperature 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 r l-pea = 22k g lna = 0db g pea = 0db v cc = 5.5v v cc = 2.7v v cc = 2.3v v out-pea (v pp ) v in-lna (v pp ) -40 -20 0 20 40 60 80 0 100 200 300 400 500 600 700 800 r l-pea =22k g lna = 0db g pea = 0db v cc = 2.7v v cc = 5v v out-pea (v pp ) t amb (c) figure 10. pea output voltage vs. resistor load figure 11. mic-bias output voltage vs. supply voltage 100 1k 10k 100k 1m 200 300 400 500 600 v cc = 2.7v v out-pea (mv pp ) r l-pea ( ) 2.02.53.03.54.04.55.05.56.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 i mic-bias = 2.5ma v mic-bias (v) v cc (v)
electrical characteristics TSH512 12/31 doc id 8120 rev 7 figure 12. mic-bias voltage vs. mc-bias current figure 1 3 . lna+alc+pea distortion vs. input voltage 01234 1.6 1.8 2.0 2.2 2.4 v cc = 2.3v v mic-bias (v) i mic-bias (ma) 0.02 0.04 0.06 0.08 0.10 0.01 0.1 1 10 r l-pea = 22k g lna = 0db g pea = 0db v cc = 5.5v v cc = 2.7v v cc = 2.3v thd lna+alc+pea +n (%) v in (v pp ) figure 14. mic-bias output voltage vs. temperature figure 15. mic-bias voltage vs. mic-bias current -40-30-20-10 0 1020304050607080 2.1 2.2 2.3 2.4 v cc = 2.7v i mic-bias = 2.5ma v mic-bias (v) t amb (c) 0123 2.20 2.25 2.30 2.35 2.40 v cc =2.7v v mic-bias (v) i mic-bias (ma)
TSH512 electrical characteristics doc id 8120 rev 7 13/31 3 . 3 rf section figure 16. vco output voltage vs. r vco figure 17. vco-bias voltage vs. vco-bias current 10k 100k 1m 300 350 400 450 500 550 600 650 700 v cc = 2.7v l = 120h (q=30) f carrier = 2.8mhz v vco-out (mv pp ) r vco ( ) 0 1020304050 1.30 1.35 1.40 1.45 v cc = 2.7v r filter = 51 c filter = 470nf v vco-bias (v) i vco-bias (ma) figure 1 8 . vco and output buffer spectrum figure 19. vco-bias voltage vs. temperature figure 20. vco and output buffer spectrum 369121518 -30 -20 -10 0 10 20 30 40 50 60 v cc = 2.7v r vco = 22k z l = 2k f carrier = 2.8mhz v buf-out (dbmv) frequency(mhz) -40-30-20-10 0 1020304050607080 1.3 1.4 1.5 1.6 v cc = 2.7v no load v vco-bias (v) t amb (c) 2.795 2.796 2.797 2.798 2.799 2.800 2.801 2.802 2.803 2.804 2.805 -30 -20 -10 0 10 20 30 40 50 60 v cc = 2.7v l = 120h (q=30) r vco = no connected z l = 2k bw = 200hz f carrier = 2.8mhz v buf-out (dbmv) frequency(mhz)
application information TSH512 14/31 doc id 8120 rev 7 4 application information this section gives application inform ation for some typical applications. 4.1 infrared stereo transmitter application (ste reo headphones) in this application, shown in figure 21 , the hi-fi stereo audio is amplified and level regulated by alc. the carrier of each transmitter tx1 or tx2 of the TSH512 is modulated in fm and buffered to drive the led. figure 21. hi-fi stereo headphone block diagram the audio signals are transmitted on the left and the right channels using 2.8- and 2.3-mhz carriers. the vox activates the tx1 transmitter when the audio signal is present ( figure 22 ). audio amp1 audi o amp2 sby1 sby2 2squelch lna lna + alc lna + alc sby buffer1 buffer2 rx2 rx1 line inputs right channel left channel vcc led photodiode filter filter 2.3 mhz 2.8 mhz vcc: 2.3 to 5.5v current < 15 ma TSH512 tsh511 20 mw / 16 20 mw / 16 power supply: 2.3 to 5.5v icc < 20 ma stereo ir ster eo hifi transmitt er headphone side h ifi s tereo : 2. 3 & 2. 8 mhz c a rrier s vox tx1 tx2 2squelch squelch rx2 rx1 led filter 20 mw / 16 20 mw / 16 : : vox tx1 tx2
TSH512 application information doc id 8120 rev 7 15/31 figure 22. application diagram dec2 1 mic-bias2 2 gnd 3 vcc 4 sby 5 vox-ints 6 vox-sens 7 vcc 8 gnd 9 mic-bias1 10 dec1 11 lna-inp1 12 lna-inn1 13 lna-out1 14 alc-int1 15 pea-inn1 16 pea-out1 17 vco-bias1 18 vcc 19 vco-a1 20 vco-b1 21 vco-out1 22 gnd 23 buf-in1 24 buf-out1 25 vcc 26 vox-mute 27 vox-intn 28 vox-timer 29 gnd 30 buf-out2 31 buf-in2 32 gnd 33 vco-out2 34 vco-b2 35 vco-a2 36 vcc 37 vco-bias2 38 pea-out2 39 pea-inn2 40 alc-int2 41 lna-out2 42 lna-inn2 43 lna-inp2 44 lna + - + - alc pea lna + - + - alc pea vox + - monostable ic2 TSH512 r23 3k9 c29 470nf r24 470k r32 10k r31 47 c33 470pf c42 2nf2 c43 100nf r36 270k r35 100k c35 470nf c34 470nf +5v r26 47k c36 56pf c37 56pf c45 6-60pf c46 12pf l2 120uh r37 47k +5v c47 68pf c38 56pf c13 220nf r21 33k c28 470nf +5v c39 470nf c30 1uf r12 470k r4 10k r3 47 c6 470pf c5 2nf2 c8 100nf r7 270k r8 100k c7 470nf c18 470nf +5v r14 47k c19 56pf c20 56pf c10 6-60pf c11 12pf r9 47k +5v c12 390pf c21 56pf c15 1uf c14 470nf +5v c40 22nf c24 22nf d4 hsdl4230 d6 hsdl4230 vcc 1 2 3 j2 jack3.5st c32 1uf c17 1uf +5v l1 120uh c26 100uf vcc c44 39pf c9 39pf r22 1k8 r20 8k2 r10 8k2 r11 1k8 c31 100nf r25 47 c16 100nf r13 47 r30 5k6 c41 10uf r2 5k6 c4 10uf nc 0 ohm vox on off r15 tx1 = 2.8mhz tx2 = 2.3mhz c23 100nf c27 100nf c22 10uf r16 150k r33 3k r34 7k5 r6 3k r5 7k5 d5 hsdl4230 d7 hsdl4230 d8 smv1212 d3 smv1212 q1 stzt2222a r19 10 r18 47 r17 2k4 r27 2k4 r28 24k r29 2k7 ic3 tsh81 +5v +5v c25 100nf r15 see note 1812ls (coilcraft) 1812ls (coilcraft) 100mw mini (1206) 3 2 6 7 8 4 r38 1k2 c48 22pf
application information TSH512 16/31 doc id 8120 rev 7 4.2 sub-carrier generator applicat ion: voice-operated wireless camera thanks to its operating frequency, the TSH512 offers t he possibility of generating usual audio sub-carriers for video applications ( figure 23 ). the camera can be voice-activated using the vox-mute output of the TSH512. the TSH512 also provides bias, amplification, alc for the electret microphone. figure 2 3 . typical block diagram for audio sub-carrier generator 4. 3 multimedia application 4. 3 .1 headset side the TSH512 is used in mono mode to transmit the signal of the electret condenser microphone of the headset. the circuit is supplied by batteries and the vox function switches off the output stages to save energy. the usual working frequency is 1.7 mhz for infrared mono operation. t s h512 lna + alc lna + alc mic. bia s mic. bia s tx2 vox s by bu ffer1 bu ffer2 vcc 6 or 6.5 mhz filter electret conden s er microphone mini a t u re c a mer a fm 2.4 ghz tr a n s mitter 6 or 6.5 mhz a u dio sub -c a rrier video vox-mute s t a nd-by s sub -c a rrier s t a nd-by tx1 t s h512 lna + alc lna + alc mic. bia s mic. bia s tx2 vox s by bu ffer1 bu ffer2 vcc 6 or 6.5 mhz filter electret conden s er microphone mini a t u re c a mer a fm 2.4 ghz tr a n s mitter 6 or 6.5 mhz a u dio sub -c a rrier video vox-mute s t a nd-by s sub -c a rrier s t a nd-by tx1
TSH512 application information doc id 8120 rev 7 17/31 figure 24. headset-side block diagram 4. 3 .2 computer side in multimedia applications, the TSH512 transmits the hi-fi stereo from the pc to the headset. figure 25. computer-side block diagram TSH512 lna + alc lna + alc mic. bias mic. bias tx2 tx1 vox sby buffer1 buffer2 photodiode vcc led vcc audi o amp2 sby1 sby2 lna 2.3 mhz band-pass tsh511 hifi stereo from the pc: 2 x 20 mw /16 1.7 mhz band-pass voice transmitted to the pc microphone tx: 1.7 mhz carrier stereo rx: 2.3 & 2.8 mhz filter 1.7 mhz reject 2.8 mhz band-pass tsh511 & 512 supply: 2.3 to 5.5v, 25 ma audi o amp1 filter filter filter rx2 rx1 squelch 1.7 mhz reject f ilter vcc - hifi - microphone tx: 1.7 mhz carrier stereo rx: 2.3 & 2.8 mhz filter -pass : filter filter filter squelch f ilter lna + alc lna + alc sby buffer1 buffer2 led photodiode tsh511 & 512 supply: 2.3 to 5.5v, 24 ma TSH512 audio amp1 audio amp2 sby1 sby2 squelch squelch lna rx2 rx1 filter tsh511 vcc 1.7 mhz band - pass hifi stereo tx: 2.3 & 2.8 mhz mono rx: 1.7 mhz voice from the headset microphone hifi stereo vox tx2 tx1
general description TSH512 18/31 doc id 8120 rev 7 5 general description the TSH512 is a 0.4- to 11-mhz dual fm analog transmitter. this circuit offers the functions needed for an advanced infrared stereo transmitter. the access pins for each section allow high versatility and therefor e a lot of applications: mono infrared transmitter, stereo transmitter, mono/stereo sub-carrier generator for video transmissions (for example the popular 2.4 ghz video links). the block diagram for the TSH512 is shown in figure 1 on page 4 . each audio input is amplified with a low noise amplifier (lna section) allowing connection to line level sources or directly to a microphone. built-in mic bias voltage references provide bias for electret condenser microphones (ecm) with a high power supply rejection ratio. each audio path also includes an automatic level control (alc) to limit the over- modulation and the distortion on very high signal amplitudes. the following operational amplifier (pea) allows a pre-emphasis transfer function before modulating the varicap diode. built-in voltage references (vco-bias) offer a regulated voltage to bias the varicap diodes. the voltage controlled oscillator (vco) is an integrated osc illator giving typically 600 mv peak-to-peak at 2.8 mhz. the output buffer section linearly amplifies the fm carr ier to provide a sinusoidal output. this sinusoidal signal reduces the inter-modulation products between the carriers, especially in two-way or in multi-carrier systems (see section 4: application information on page 14 ). the voice operated transmit function (vox) automatically detects when an audio signal appears over the background noise. the standby of the second transmitter reduces consumption in mono operation. 5.1 lna section: low noise amplifier for each transmitter, the audio source is connected to the lna. the lna stage is a low noise operational amplifier typically usable with a gain from 0 to 40 db.
TSH512 general description doc id 8120 rev 7 19/31 figure 26. lna schematics the lna gain is given by: g lna (db) = 20.log(1+r lna2 /r lna1 ) the high-pass cut-off frequency is: f hpf = 1/(2. . r lna1 .c lna1 ) the lowpass filter cut-off frequency is: f lpf = 1/(2. . r lna2 .c lna2 ) if you connect an external circuit to the lna output, the impedance of this external circuit should be higher than 10 m and the capacitance lower than 50 pf in order to keep a good stability. note: the capacitor c must be connected directly to input pin 12. 5.2 electret condenser microphone source when an electret condenser microphone (ecm) is used, a high gain lna is recommended, but low frequencies have to be attenuated. the ecm must be biased with a stable and clean reference voltage. the TSH512 provides the lna and the mic-bias sections to perform this function (see section 5.3. mic-bias section: microphone bias voltage ).
general description TSH512 20/31 doc id 8120 rev 7 figure 27. electret condenser microphone source the capacitor c in series with the microphone stops the dc coming from mic-bias. the resistor r provides the dc from mic-bias to supply the ecm. thanks to the autom atic level control (alc), the great variations of amplitude will not over- modulate the transmitter (refer to the section 5.4: alc section: automatic level control ). the self-adaptive vox (voice operated transmit) offers automatic transmitting with a good discrimination of the background noise (see section 5.5: vox description: voice operated transmit on page 21 ). 5. 3 mic-bias section: microphone bias voltage the mic-bias bias voltages are dedicated to the bias of electret condenser microphones. these bias voltages on pin 10 for tx1 and pin 2 for tx2 exhibit a low voltage noise density of 22 nv/ hz ). this allows more than 55 db s/n considering a bandwidth of 7 khz ( figure 27 ). the mic-bias voltag e is related to v cc as follows (with i mic-bias = 2.5 ma): v mic-bias = 0.844.vcc-0.140 (volts) moreover, the supply rejection ratio is guaranteed to be better than 50 db without any decoupling capacitor. to address biasing of most of the microphones, the current drive capability is 2.5 ma. the mic-bias voltage depends linearly on the supply voltage v cc (refer to figure 11 on page 11 ).
TSH512 general description doc id 8120 rev 7 21/31 5.4 alc section: automatic level control both transmitters of the TSH512 include an aut omatic level control (alc). when the level of the audio signal is too high, the alc compre sses the signal in order to avoid over- modulation of the fm vco. in this way, the alc reduces the distortion and maintains a reduced transmit spectrum with very high amplitude signals. figure 2 8 . automatic level control schematics the alc features a 20 db gain and an output signal regulated to 700 mvpp in compression. the attack time is the response time of the alc to go from the linear amplification to the compression region. the attack time mainly depends on the capacitor value of c alc . a typical value of c alc is 1 f with music as the audio signal (refer to figure 22 on page 15 ). the decay time is the response time the alc requires to recover to full gain amplifying mode after being in compression mode. the decay time depends mainly on the r alc resistor value. a typical value of r alc is 470 k , with music as audio signal ( figure 22 ). 5.5 vox description: voice operated transmit the voice operated transmit (vox) section reduces consumption when there is no audio signal to transmit. when the vox detects that no audio signal is present, it mutes the output buffers of tx1 and tx2 and provides the logic signal vox-mute to switch-off the external led drivers if needed. the audio signal of tx1 is amplified with a gain dependent on the values of r sens and c sens . r sens and c sens are connected to pin 7. the high-pass filtering has the following cut-off frequency: f hpf 1 2 r sens c sens ? () ------------------------------------------------- - =
general description TSH512 22/31 doc id 8120 rev 7 figure 29. vox delay and sensitivity schematics on pin 6, r peak and c peak integrate the rectified audio signal with a short time constant. this filtered signal follows the audio amplitude. figure 3 0. vox integrator and monostable schematics the self-adaptive vox threshold is necessary because the ambient background noise variation is slow compared to the voice or the music. on pin 28, r comp and c comp integrate the amplitude to follow the background amplitude. therefore, the comparator switches when an audio signal appears over the background noise. referring to figure 2 , c comp will be typically a 100 nf capacitor and r comp will be determined depending on the audio signal. as soon as an audio signal is detected, the output of the monostable switches to "high" state and enables both output buffers. the monostable output is pin 27 and is called vox-mute.
TSH512 general description doc id 8120 rev 7 23/31 the monostable holds the TSH512 in transmit mode during a delay fixed by the value of c trig connected to pin 29. note that the vox function is activated when the audio signal enters the first transmitter tx1. when the application needs a permanent transmission, it is possible to inhibit the vox function, by removing the ctrig capacitor and connecting pin 29 to ground. as soon as the TSH512 is powered-on, the internal reset circuitry sets the vox-mute to high state to enable transmission. the transmission remains during the monostable timing and continues if an audio signal triggers the monostable. figure 3 1. vox state at power-on vox delay 1.4v 5 a ------------ ?? ?? c trig ? = time vox -mute power supply on off vox delay (ctrig) 0 1 high state if retriggered by audio
general description TSH512 24/31 doc id 8120 rev 7 5.6 pea section: pre-emphasis the amplitude-regulated audio coming from the alc feeds the positive input of the operational amplifier called pea (pre-emphasis). the pre-emphasis consis ts in a high-pass filter in order to compensate the behavior of the fm transmission. figure 3 2. pre-emphasis schematics r pea1 and c pea1 set the time constant of the pre-emphasis as: = r pea1 . c pea1 50 s or 75 s time constants are generally used. choosing the gain of the pea stage also allows one to set the right mo dulation level to the varicap diode. the gain in the passband is: g pea = 1+ (r pea2 /r pea1 )
TSH512 general description doc id 8120 rev 7 25/31 5.7 vco section: voltage-controlled oscillator each TSH512 transmitter has its own oscillator to generate the carrier. the audio signal is applied to the varicap diode to perform the frequency modulation. thanks to the vco-bias voltage reference, the dc bias of the varicap is stabilized. the high power supply rejection ratio (psrr) of the vco-bias ensures good immunity with the noise of the power supply. figure 33 . vco schematics the generated frequency can be set from 400 khz to 11 mhz by external components. refer to ta b l e 1 for the usual frequencies in infrared audio. the working frequency is: where c t is the total capacity of c l , c p , c s and c v : c t = 1/(1/c c +1/c l ) with c c = c p +1/(1/c v +1/c s ) it is possible to use varicap diodes smv1212 (alpha ind.) or zc833 (zetex). the output level of the vco can be reduced by adding the resistor rvco between pin 19 and pin 20 or between pin 36 and pin 37 for tx1 and tx2 respectively. table 5. usual infrared frequencies ir frequency in mhz applications 1.6 am mono 1.7 fm mono 2.3 fm right channel 2.8 fm left channel or mono f vco 1 2 lc t ? () -------------------------------- - =
general description TSH512 26/31 doc id 8120 rev 7 5. 8 output buffer section the output buffers can deliver a sinusoidal signal with a 1.5 v pp amplitude in a 1 k load. this impedance is compatible with popular biasing circuitry of external transistor drivers of ir leds. the vox-mute logic signal can be used to control the external led drivers. when the audio is not present on the tx1 input, vox-mute is in low state, the TSH512?s internal buffers are muted, and the external drivers can be switched off by controlling their bias. 5.9 sby pin: standby for mono operation a high state on the stan dby pin (sby) sets the second tr ansmitter tx2 to power-down. the sby pin is typically used when the TSH512 is us ed as a mono transmi tter (that is, infrared microphone transmitter).
TSH512 package information doc id 8120 rev 7 27/31 6 package information in order to meet environmental requirements, st offers these devices in different grades of ecopack ? packages, depending on their level of environmental compliance. ecopack ? specifications, grade definitions and product status are available at: www.st.com . ecopack ? is an st trademark.
package information TSH512 28/31 doc id 8120 rev 7 6.1 tqfp44 package information figure 3 4. tqfp44 package mechanical drawing table 6. tqfp44 package mechanical data ref. dimensions millimeters inches min. typ. max. min. typ. max. a 1.6 0.063 a1 0.05 0.15 0.002 0.006 a2 1.35 1.40 1.45 0.053 0.055 0.057 b 0.30 0.37 0.45 0.012 0.015 0.018 c 0.09 0.20 0.004 0.008 d 11.80 12 12.20 0.465 0.472 0.480 d1 9.80 10.00 10.20 0.386 0.394 0.402 d3 8.00 0.315 e 11.80 12.00 12.20 0.465 0.472 0.480 e1 9.80 10.00 10.20 0.386 0.394 0.402 e3 8.00 0.315 e 0.80 0.031 l 0.45 0.60 0.75 0.018 0.024 0.030 l1 1.00 0.039 k 03.57 03.57 ccc 0.10 0.004
TSH512 ordering information doc id 8120 rev 7 29/31 7 ordering information table 7. order codes part number temperature range package packing marking TSH512cf -40 c to +85c tqfp44 tr ay TSH512c TSH512cft tape & reel TSH512cyft (1) 1. qualification and characterizati on according to aec q100 and q003 or equivalent, advanced screening according to aec q001 & q 002 or equivalent. tqfp44 (automotive grade level) tape & reel TSH512cyf
revision history TSH512 30/31 doc id 8120 rev 7 8 revision history table 8 . document revision history date revision changes 08-aug-2001 1 first release corresponding to preliminary data version of datasheet. 09-sep-2001 2 datasheet updated for maturity 30: ? esd sensitive device sentence added ? 4 curves updated ? electrical parameters updated 01-dec-2003 3 specific content changes as follows: ? application diagrams updated ? releases on curves ? application schematic diagram update ? electrical parameters updated 01-apr-2005 4 pin connection updated on figure 1 on page 4 . rthja value added on table 1 on page 3 . schematic updated on figure 2 on page 6 . schematic updated on figure 26 on page 19 . 14-oct- 2005 5 ppap reference inserted in the datasheet, see order codes table. 13-nov-2007 6 document reformatted with minor text changes. added footnote for automotive grade order codes to order codes table. 28-may-2009 7 added data at -40 c < t amb < +85 c in ta bl e 4 . updated package mechanical drawing in chapter 6: package information .
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