TSH512_09

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 pins 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 1 2 3 LNA 4 44 43 42 41 40 39 38 37 36 35 34 VCO PEA ALC F TQFP44 10 x 10 mm Pin connections (top view) 33 32 ■ ■ ■ ■ ■ Infrared hi-fi stereo transmitters Infrared headsets Stereo sub-carriers for video transmitters Voice-operated wireless webcams FM IF transmit systems TSH512 VOX + LNA Monostable 5 6 7 8 9 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-modulated 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. + - ALC 10 11 + PEA VCO 12 13 14 15 16 The TSH512 forms a chipset with the dual receiver TSH511. May 2009 Doc ID 8120 Rev 7 TX2 Output buffer + + - Applications 31 30 29 28 27 26 TX1 Output buffer 25 24 23 17 18 19 20 21 22 1/31 www.st.com 31 Contents TSH512 Contents 1 2 3 Absolute maximum ratings and operating conditions . . . . . . . . . . . . . 3 Device diagrams and schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.1 3.2 3.3 Supply section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Audio section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 RF section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.1 4.2 4.3 Infrared stereo transmitter application (stereo headphones) . . . . . . . . . . 14 Sub-carrier generator application: voice-operated wireless camera . . . . 16 Multimedia application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 4.3.1 4.3.2 Headset side . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Computer side . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 5 General description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 LNA section: low noise amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Electret condenser microphone source . . . . . . . . . . . . . . . . . . . . . . . . . . 19 MIC-BIAS section: microphone bias voltage . . . . . . . . . . . . . . . . . . . . . . 20 ALC section: automatic level control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 VOX description: voice operated transmit . . . . . . . . . . . . . . . . . . . . . . . . 21 PEA section: pre-emphasis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 VCO section: voltage-controlled oscillator . . . . . . . . . . . . . . . . . . . . . . . . 25 Output buffer section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 SBY pin: standby for mono operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 6 Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 6.1 TQFP44 package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 7 8 Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 2/31 Doc ID 8120 Rev 7 TSH512 Absolute maximum ratings and operating conditions 1 Absolute maximum ratings and operating conditions Table 1. Absolute maximum ratings Parameter Supply voltage(1) Operating free air temperature range Storage temperature Maximum junction temperature Thermal resistance junction to case Thermal resistance junction to ambient area Class (2) Symbol VCC Toper Tstg Tj Rthjc Rthja Latch-up Value 7 -40 to +85 -65 to +150 150 14 45 A Unit V °C °C °C °C/W °C/W ESD sensitive device: handling precautions required ESD HBM: human body model(3) except pins 20 and CDM: charged device model(4) MM: machine model(5) 36 2 1 0.2 kV 1. All voltage values, except differential voltage, are with respect to network ground terminal. 2. Corporate ST Microelectronics procedure number 0018695. 3. Human body model: a 100 pF capacitor is charged to the specified voltage, then discharged through a 1.5 kΩ 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. This 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 Ω). This is done for all couples of connected pin combinations while the other pins are floating. Table 2. Operating conditions Parameter Supply voltage Audio frequency range Carrier frequency range Value 2.3 to 5.5 20 to 20,000 0.4 to 11 Unit V Hz MHz Symbol VCC faudio fcarrier Doc ID 8120 Rev 7 3/31 Device diagrams and schematics TSH512 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 VCO-BIAS2 LNA-OUT2 PEA-OUT2 LNA-INP2 PEA-INN2 LNA-INN2 ALC-INT2 VCO-OUT2 34 VCO-A2 36 44 43 42 41 40 39 38 37 35 DEC2 MIC-BIAS2 GND VCC SBY VOX-INTS VOX-SENS VCC GND MIC-BIAS1 DEC1 1 PEA 2 3 LNA 4 5 6 7 8 LNA 9 10 11 ALC VCO VCO-B2 VCC 33 32 GND BUF-IN2 BUF-OUT2 GND VOX-TIMER VOX-INTN VOX-MUTE VCC BUF-OUT1 BUF-IN1 GND TSH512 VOX + Monostable + - ALC + PEA VCO 12 13 14 15 16 VCO-BIAS1 LNA-INP1 PEA-INN1 LNA-INN1 PEA-OUT1 LNA-OUT1 4/31 Doc ID 8120 Rev 7 VCO-OUT1 VCO-A1 ALC-INT1 VCO-B1 VCC TX2 Output buffer + + - 31 30 29 28 27 26 TX1 Output buffer 25 24 23 17 18 19 20 21 22 TSH512 Table 3. Pin 1 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 Device diagrams and schematics Pin descriptions Pin name Related to TX2 TX2 TX1 & TX2 TX1 & TX2 TX1 & TX2 TX1 TX1 TX1 TX1 TX1 TX1 TX1 TX1 TX1 TX1 TX1 TX1 TX1 TX1 TX1 & TX2 TX1 & TX2 TX1 & TX2 TX2 TX2 TX2 TX2 Direction(1) O I O I I O I O O O I O O O I O Pin description Decoupling capacitor for internal voltage reference Microphone bias Ground Supply voltage Standby control (input pin) Time constant terminal for audio signal integrator in VOX Gain adjustment for VOX input sensitivity Supply voltage Ground Microphone bias Decoupling capacitor for internal voltage reference LNA positive input LNA negative input LNA output Time constant terminal for integrator in ALC Pre-emphasis amplifier negative input Pre-emphasis amplifier output Bias for external VCO components Supply voltage Oscillator component connection Oscillator component connection VCO output Ground Input to the output buffer Output of the output buffer Supply voltage Mute control (output pin) in VOX Time constant terminal for noise integrator in VOX Rise time for timer in VOX Ground Output of the output buffer Input to the output buffer Ground VCO output Oscillator component connection DEC2 MIC-BIAS2 GND VCC SBY VOX-INTS VOX-SENS VCC GND MIC-BIAS1 DEC1 LNA-INP1 LNA-INN1 LNA-OUT1 ALC-INT1 PEA-INN1 PEA-OUT1 VCO-BIAS1 VCC VCO-A1 VCO-B1 VCO-OUT1 GND BUF-IN1 BUF-OUT1 VCC VOX-MUTE VOX-INTN VOX-TIMER GND BUF-OUT2 BUF-IN2 GND VCO-OUT2 VCO-B2 Doc ID 8120 Rev 7 5/31 Device diagrams and schematics Table 3. Pin 36 37 38 39 40 41 42 43 44 TSH512 Pin descriptions (continued) Pin name Related to TX2 TX2 TX2 TX2 TX2 TX2 TX2 TX2 Direction(1) O O I O I I Pin description Oscillator component connection Supply voltage Bias for external VCO components Pre-emphasis amplifier output Pre-emphasis amplifier negative input Time constant terminal for internal peak detector in ALC LNA output LNA negative input LNA positive input VCO-A2 VCC VCO-BIAS2 PEA-OUT2 PEA-INN2 ALC-INT2 LNA-OUT2 LNA-INN2 LNA-INP2 1. Pin directions: I = input pin, O = output pin, - = pin to connect to supply or decoupling capacitors or external components. Figure 2. Typical application schematics for stereo infrared transmitter 6/31 Doc ID 8120 Rev 7 TSH512 Electrical characteristics 3 Table 4. Symbol Electrical characteristics Electrical characteristics for VCC = 2.7 V, Tamb = 25° C, faudio = 1 kHz, fcarrier = 2.8 MHz (unless otherwise specified) (1) Parameter Test conditions Min. Typ. Max. Unit Overall circuit TX1 on, TX2 on, MIC-BIAS1 and MIC-BIAS2 not used: VOX-MUTE=1 output buffers on VOX-MUTE=0, output buffers off -40° C < Tamb < +85° C VOX-MUTE=1 output buffers on VOX-MUTE=0, output buffers off TX1 on, TX2 off, MIC-BIAS1 and MIC-BIAS2 not used: VOX-MUTE=1,output buffers on Current consumption with VOX-MUTE=0, output buffers off TX2 in standby: SBY (pin5) active -40° C < T < +85° C amb ICC_TOT Current consumption TX1 and TX2 are on 16 11 18.6 12.8 19.6 13.8 mA ICC_SBY 10 7 11.5 8 12.1 8.6 mA VOX-MUTE=1, output buffers on VOX-MUTE=0, output buffers off LNA sections (for TX1 and TX2) GBPLNA Gain bandwidth product Input resistance on positive input: (LNA-INP1 pin 12 or LNA-INP2 pin 44) Total harmonic distortion Equivalent input noise voltage GLNA = 0 dB, VoutLNA = 700 mVPP -40° C < Tamb < +85° C GLNA = 40 dB, at f = 1 kHz , RS = 390 Ω Rfeedback = 39 kΩ 6 No external load 7 MHz RinLNA 30 kΩ 0.01 0.05 % 0.05 nV/√ Hz THDLNA En Automatic level control (ALC) section GALC VALC_OUT Voltage gain Regulated output level (at positive input of the PEA -40° C < Tamb < +85° C amplifier) 600 597 20 710 800 mVpp 803 dB Pre-emphasis amplifier (PEA) section GBPPEA VOpp-PEA Gain bandwidth product (PEA-OUT1 pin 17 or PEA-OUT2 pin 39) Output voltage No load RL = 22 kΩ 9 550 MHz mVpp Doc ID 8120 Rev 7 7/31 Electrical characteristics Table 4. Symbol TSH512 Electrical characteristics for VCC = 2.7 V, Tamb = 25° C, faudio = 1 kHz, fcarrier = 2.8 MHz (unless otherwise specified) (continued) (1) Parameter Test conditions Min. Typ. Max. Unit Audio LNA+ALC+PEA sections GLNA = 0 dB, f = 1 kHz Total harmonic distortion in (V in)ALC < 25 mVrms (-30 dBu) linear region on PEA-OUT1 R = 22 kΩ tied to GND L pin17 or PEA-OUT2 pin 39 -40° C < Tamb < +85° C (Vin)ALC = 36 mVrms (-27 dBu) (Vin)ALC= 100 mVrms (-18 dBu) Total harmonic distortion in RL = 22 kΩ tied to GND compression region -40° C < Tamb < +85° C (Vin)ALC = 36 mVrms (-27 dBu) (Vin)ALC= 100 mVrms (-18 dBu) Phase margin at PEA-OUT1 pin 17 or PEA-OUT2 pin 39 RL = 22 kΩ LNA and PEA at unity gain Vin = 40 mV 0.05 0.15 % 0.25 1.3 3 1.7 4 % 2.5 5.3 70 ° THDALC THDAGC ΦΜPEA Microphone biasing section VMIC-BIAS Microphone biasing voltage IMIC-BIAS = 2.5 mA (Section 5.3 on page 20) -40° C < Tamb < +85° C VMIC-BIAS temperature coefficient Over temp. range: [0, 70° C] [-40, 85° C] IMIC-BIAS = 2.5 mA 2.5 50 22 42 2.15 2.14 260 460 2.25 2.35 V 2.36 ΔVMIC-BIAS ppm/°C IMIC-BIAS PSRRMIC-BIAS enMIC-BIAS MIC-BIAS current capability Over VCC range [2.3 V–5.5 V] Power supply rejection ratio At 1 kHz and Vripple = 25 mVRMS of MIC-BIAS Equivalent input noise of MIC-BIAS VCC = 2.7 V VCC = 5.0 V mA dB nV/√ Hz Vox operated switch (VOX) section IVOX-TIMER VTHVOX-TIMER VMUTE_L Monostable current source VCC = 2.7V (VOX-TIMER pin 29) Threshold voltage of the Monostable (time constant) Low level output voltage (VOX-MUTE pin 27) High level output voltage (VOX-MUTE pin 27) RL = 2 kΩ -40° C < Tamb < +85° C RL = 2 kΩ -40° C < Tamb < +85° C VCC-0.3 VCC0.32 V 5 1.4 0.2 V 0.2 µA V VMUTE_H 8/31 Doc ID 8120 Rev 7 TSH512 Table 4. Symbol Standby VSBY_IL maximum VSBY_IH minimum VCO section VVCO-BIAS VCO-BIAS output voltage (VCO-BIAS1 pin 18 or VCO-BIAS2 pin 38) VCO-BIAS output current capability With no load -40° C < Tamb < +85° C VVCO-BIAS > 1.38 V 2.3 V < VCC < 5.5 V [0, 70° C] VCC = 2.7 V [0, 70° C] VCC = 5.0 V [-40, 85° C] VCC = 2.7 V [-40, 85° C] VCC = 5.0 V At 1 kHz, L = 120 µH (Q = 30) and RVCO not connected With no load Maximum low level input voltage of standby input (SBY pin 5) Minimum high level input voltage of standby input (SBY pin 5) Electrical characteristics Electrical characteristics for VCC = 2.7 V, Tamb = 25° C, faudio = 1 kHz, fcarrier = 2.8 MHz (unless otherwise specified) (continued) (1) Parameter Test conditions Min. Typ. Max. Unit 0.1xVCC V 0.9xVCC V 1.43 1.38 1.47 1.51 1.56 VDC IVCO-BIAS 40 8 +265 +356 +265 +356 -80 43 µA mV/V ppm/°C ppm/°C ppm/°C ppm/°C dBc dB δVVCO-BIAS VCO-BIAS voltage drift PNLO SVRVCO-BIAS Phase noise Supply voltage rejection ratio of VCO-BIAS VCO output impedance (VCO-OUT1 pin 22 or VCO-OUT2 pin 34) Minimum load impedance ZVCO-OUT ZLVCO-OUT minimum 400 Ω kΩ 1 L = 120 µH (Q = 30) VCO output connected to output buffer input RVCO = 100 kΩ -40° C < Tamb < +85° C 580 569 620 660 mVpp 671 VVCO-OUT VCO output level Output buffer ZBUF-IN GOB Input impedance (BUF-IN1 pin 24 or BUF-IN2 pin 32) Linear voltage gain Output AC voltage at 1dB compression point VBUF-OUT AC Output AC voltage (BUF-OUT1 pin 25 or BUF-OUT2 pin 31) ZL = 2 kΩ ZL = 2 kΩ VBUF-IN = 0.60 Vpp -40° C < Tamb < +85° C 1.35 1.33 400 10 1.3 1.5 1.7 1.72 Vpp kΩ dB Doc ID 8120 Rev 7 9/31 Electrical characteristics Table 4. Symbol VBUF-OUT DC H2BUF-OUT H3BUF-OUT TSH512 Electrical characteristics for VCC = 2.7 V, Tamb = 25° C, faudio = 1 kHz, fcarrier = 2.8 MHz (unless otherwise specified) (continued) (1) Parameter Output DC voltage 2nd harmonic level 3rd harmonic level Test conditions DC output current = 0.4 mA VBUF-OUT = 1.2 Vpp and ZL = 2 kΩ VBUF-OUT = 1.2 Vpp and ZL = 2 kΩ Min. Typ. 1.25 -40 -30 Max. Unit VDC dBc dBc 1. Limits over -40° C < Tamb < +85° C range are guaranteed by statistical correlation. 3.1 Figure 3. 18 16 14 12 ICC(mA) 10 8 6 4 2 0 0 Supply section Supply current vs. supply voltage TX1+TX2+Buffers TX1+TX2 TX1+Buffers TX1 1 2 3 VCC(V) 4 5 6 3.2 Figure 4. 1 Audio section LNA distortion vs. frequency Figure 5. 100 LNA distortion vs. LNA output voltage GLNA = 0dB VCC = 2.7V VCC = 2.3V VCC = 2.7V GLNA = 0dB VOUT-LNA = 700mVpp THDLNA+N (%) THDLNA+N (%) 10 1 0.1 0.1 0.01 VCC = 5.5V 0.01 10 1E-3 100 1000 Frequency (Hz) 10000 0 200 400 600 800 1000 1200 1400 1600 VOUT-LNA(mVpp) 10/31 Doc ID 8120 Rev 7 TSH512 Electrical characteristics Figure 6. 16 14 Supply current vs. temperature Figure 7. 10 LNA distortion vs. frequency VCC = 2.7V GLNA = 40dB VOUT-LNA = 700mVpp TX1+TX2+Buffers TX1+TX2 THDLNA+N (%) 12 ICC(mA) 10 8 6 4 2 0 0 VCC = 2.7V TX1 TX1+Buffers 1 20 40 TAMB(°C) 60 80 0.1 10 100 1000 Frequency (Hz) 10000 Figure 8. 0.8 0.7 0.6 VOUT-PEA(VPP) PEA output voltage vs. LNA input voltage Figure 9. 800 700 600 PEA output voltage vs. temperature 0.5 0.4 0.3 0.2 0.1 0.0 0.00 0.05 0.10 0.15 VCC = 2.7V VCC = 5.5V VOUT-PEA(VPP) VCC = 2.3V 500 400 300 200 100 0 -40 RL-PEA=22KΩ GLNA = 0dB GPEA = 0dB VCC = 2.7V VCC = 5V RL-PEA = 22KΩ GLNA = 0dB GPEA = 0dB 0.20 0.25 0.30 0.35 0.40 -20 0 20 TAMB(°C) 40 60 80 VIN-LNA(Vpp) Figure 10. PEA output voltage vs. resistor load 600 VCC = 2.7V 500 VOUT-PEA(mVPP) Figure 11. MIC-BIAS output voltage vs. supply voltage 4.5 IMIC-BIAS = 2.5mA 4.0 VMIC-BIAS(V) 3.5 3.0 2.5 2.0 400 300 200 100 1k 10k RL-PEA(Ω ) 100k 1M 1.5 2.0 2.5 3.0 3.5 4.0 V CC (V) 4.5 5.0 5.5 6.0 Doc ID 8120 Rev 7 11/31 Electrical characteristics TSH512 Figure 12. MIC-BIAS voltage vs. MC-BIAS current 2.4 Figure 13. LNA+ALC+PEA distortion vs. input voltage 10 RL-PEA = 22KΩ GLNA = 0dB GPEA = 0dB THDLNA+ALC+PEA+N (%) 2.2 VMIC-BIAS(V) VCC = 2.3V VCC = 2.7V 1 VCC = 2.3V 2.0 1.8 0.1 1.6 0 1 2 IMIC-BIAS(mA) VCC = 5.5V 3 4 0.01 0.02 0.04 0.06 VIN(Vpp) 0.08 0.10 Figure 14. MIC-BIAS output voltage vs. temperature 2.4 VCC = 2.7V IMIC-BIAS = 2.5mA Figure 15. MIC-BIAS voltage vs. MIC-BIAS current 2.40 VCC=2.7V 2.35 2.3 VMIC-BIAS(V) VMIC-BIAS(V) 2.30 2.2 2.25 2.1 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 TAMB(°C) 2.20 0 1 IMIC-BIAS(mA) 2 3 12/31 Doc ID 8120 Rev 7 TSH512 Electrical characteristics 3.3 RF section Figure 17. VCO-BIAS voltage vs. VCO-BIAS current 1.45 VCC = 2.7V Rfilter = 51Ω Cfilter = 470nF 1.40 VVCO-BIAS(V) Figure 16. VCO output voltage vs. RVCO 700 650 600 VVCO-OUT(mVPP) VCC = 2.7V L = 120µH (Q=30) FCARRIER = 2.8MHz 550 500 450 400 350 300 10k 1.35 1.30 100k RVCO(Ω ) 1M 0 10 20 30 40 50 IVCO-BIAS(mA) Figure 18. VCO and output buffer spectrum 60 50 40 VBUF-OUT(dBmV) Figure 19. VCO-BIAS voltage vs. temperature 1.6 VCC = 2.7V No Load 30 20 10 0 -10 -20 -30 3 6 9 VVCO-BIAS(V) 1.4 1.3 -40 -30 -20 -10 VCC = 2.7V RVCO = 22kΩ Z L = 2 kΩ FCARRIER = 2.8MHz 1.5 12 15 18 0 10 20 30 40 50 60 70 80 TAMB(°C) Frequency(MHz) Figure 20. VCO and output buffer spectrum 60 50 40 VBUF-OUT(dBmV) 30 20 10 0 -10 -20 -30 2.795 2.796 2.797 2.798 2.799 2.800 2.801 VCC = 2.7V L = 120µH (Q=30) RVCO = no connected Z L = 2 kΩ BW = 200Hz FCARRIER = 2.8MHz 2.802 2.803 2.804 Frequency(MHz) Doc ID 8120 Rev 7 2.805 13/31 Application information TSH512 4 Application information This section gives application information for some typical applications. 4.1 Infrared stereo transmitter application (stereo 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 IR stereo HiFi transmitter Headphone side Vcc: 2.3 to 5.5V Current < 15 mA 2.3 MH z Right channel TSH512 LNA + ALC filter TSH511 Audio amp2 20 mW / 16 Ω buffer2 TX2 SBY photodiode Vcc LNA Line inputs VOX LED SQUELCH ²SQUELCH RX2 Left channel buffer1 TX1 LNA + ALC : c eo H z ter i s 2.8 M F Hi & 2.3 filter Power supply: : 2.3 to 5.5V Icc < 20 mA stereo 2.8 MH z 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). 14/31 Doc ID 8120 Rev 7 SBY1 SBY2 s i er arr Audio amp1 RX1 20 mW / 16 Ω TSH512 TX2 = 2.3MHz R7 270K SMV1212 390pF C11 12pF 39pF L1 120uH 1812LS (Coilcraft) C20 56pF 56pF D3 C12 C4 10uF C5 2nF2 R5 7K5 R6 3K 5K6 R2 47 R3 10K R4 C8 100nF R8 100K 6-60pF C10 C19 C6 470pF C7 470nF C9 R9 47K C17 1uF 470K R12 +5V R14 47K R15 Vcc VOX ON OFF C26 100uF Vcc 47 R13 R10 C16 470nF C18 +5V NC 0 Ohm 44 41 40 42 36 35 43 38 39 37 34 Figure 22. Application diagram 8K2 100nF R11 1K8 D4 HSDL4230 C27 100nF D5 HSDL4230 D6 HSDL4230 LNA-INP2 ALC-INT2 LNA-OUT2 PEA-OUT2 DEC2 BUF-IN2 10uF R17 22nF 2K4 C24 VCO-BIAS2 VCO-OUT2 1 GND 32 31 30 29 28 27 +5V 26 25 24 23 R28 C38 56pF R29 C39 470nF C40 R27 22nF 2K4 100nF C22 3 LNA-INN2 PEA-INN2 VCO-A2 VCO-B2 1uF C15 VCC 56pF C21 See Note R15 33 +5V C25 7 2 470nF D7 HSDL4230 100nF R18 Q1 STZT2222A +5V C14 3 ALC BUF-OUT2 GND VOX-TIMER VOX-INTN Monostable VCC ALC LNA + PEA + BUF-IN1 GND BUF-OUT1 VOX-MUTE 4 VCC SBY VOX-INTS VOX-SENS + VCC GND MIC-BIAS1 DEC1 LNA-INP1 LNA-INN1 LNA-OUT1 ALC-INT1 PEA-INN1 PEA-OUT1 VCC VCO-A1 VCO-B1 VCO-OUT1 VOX TSH512 IC2 R16 150K C23 MIC-BIAS2 LNA + GND PEA + IC3 TSH81 2 4 8 6 47 C48 22pF R38 1K2 5 220nF J2 1 C13 C29 3K9 R23 470nF 6 7 8 +5V C28 2 3 R21 33K 470nF JACK3.5ST R19 10 100mW mini (1206) 9 10 11 VCO-BIAS1 12 13 14 15 16 17 18 19 20 21 R20 C32 R22 1K8 100nF 470k R24 C34 +5V 470nF 470nF C35 R35 100K 470pF C33 1uF 47 R25 8K2 C31 +5V R26 47K C37 56pF C36 56pF 39pF C44 C45 6-60pF L2 120uH 1812LS (Coilcraft) R30 R33 3K 5K6 R31 R32 10K 47 C42 2nF2 100nF C43 22 R36 270K SMV1212 C47 R34 7K5 C41 10uF Application information TX1 = 2.8MHz 68pF Doc ID 8120 Rev 7 C30 1uF +5V 24K 2K7 47K R37 C46 D8 12pF 15/31 Application information TSH512 4.2 Sub-carrier generator application: voice-operated wireless camera Thanks to its operating frequency, the TSH512 offers the 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 23. Typical block diagram for audio sub-carrier generator Miniature camera Video S Sub-carrier FM 2.4 GHz transmitter Stand-By Stand-By TS H512 LNA + ALC buffer2 TX2 MIC. BIAS SBY Vcc Electret Condenser Microphone VOX MIC. BIAS VOX-MUTE buffer1 TX1 LNA + ALC 6 or 6.5 MHz Audio sub-carrier 6 or 6.5 MHz filter 4.3 4.3.1 Multimedia application 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. 16/31 Doc ID 8120 Rev 7 TSH512 Figure 24. Headset-side block diagram Application information TSH511 & 512 supply: : 2.3 to 5.5V, 25 mA HiFi stereo from the PC: 2 x 20 mW /16 Ω 1.7 MHz reject filter 2.3 MHz Band-pass filter TSH511 Voice transmitted to the PC Audio amp2 SQUELCH RX2 LNA photodiode TSH512 LNA + ALC buffer2 Vcc SBY Vcc MIC. BIAS Audio amp1 VOX MIC. BIAS LED SBY2 SBY1 filter 1.7 MHz reject TX2 RX1 filter 2.8 MHz Band-pass -pass buffer1 TX1 LNA + ALC 1.7 MHz Band-pass - filter Microphone Tx: 1.7 MHz carrier Stereo Rx: 2.3 & 2.8 MHz 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 TSH511 & 512 supply: 2.3 to 5.5V, 24 mA HiFi stereo Voice from the headset microphone mono Rx: 1.7 MHz TSH511 photodiode Audio amp2 LNA TSH512 LNA + ALC SQUELCH SBY1 Vcc HiFi stereo Tx: 2.3 & 2.8 MHz buffer2 RX2 TX2 Audio amp1 SBY2 RX1 SBY LED VOX filter LNA + ALC 1.7 MHz Band-pass buffer1 TX1 Doc ID 8120 Rev 7 17/31 General description TSH512 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 therefore 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 overmodulation 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 oscillator giving typically 600 mV peak-to-peak at 2.8 MHz. The output buffer section linearly amplifies the FM carrier 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. 18/31 Doc ID 8120 Rev 7 TSH512 Figure 26. LNA schematics General description The LNA gain is given by: GLNA (dB) = 20.Log(1+RLNA2/RLNA1) The high-pass cut-off frequency is: fHPF = 1/(2.π.RLNA1.CLNA1) The lowpass filter cut-off frequency is: fLPF = 1/(2.π. RLNA2.CLNA2) If you connect an external circuit to the LNA output, the impedance of this external circuit should be higher than 10 mΩ 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). Doc ID 8120 Rev 7 19/31 General description Figure 27. Electret condenser microphone source TSH512 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 automatic level control (ALC), the great variations of amplitude will not overmodulate 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/√ ). This allows more than 55 dB S/N considering a bandwidth of 7 kHz Hz (Figure 27). The MIC-BIAS voltage is related to VCC as follows (with I MIC-BIAS= 2.5 mA): VMIC-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 VCC (refer to Figure 11 on page 11). 20/31 Doc ID 8120 Rev 7 TSH512 General description 5.4 ALC section: automatic level control Both transmitters of the TSH512 include an automatic level control (ALC). When the level of the audio signal is too high, the ALC compresses the signal in order to avoid overmodulation of the FM VCO. In this way, the ALC reduces the distortion and maintains a reduced transmit spectrum with very high amplitude signals. Figure 28. 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 CALC. A typical value of CALC is 1 µF 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 RALC resistor value. A typical value of RALC is 470 kΩ 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 Rsens and Csens. Rsens and Csens are connected to pin 7. The high-pass filtering has the following cut-off frequency: 1 f HPF = ------------------------------------------------2 π ( R sens ⋅ C sens ) Doc ID 8120 Rev 7 21/31 General description Figure 29. VOX delay and sensitivity schematics TSH512 On pin 6, Rpeak and Cpeak integrate the rectified audio signal with a short time constant. This filtered signal follows the audio amplitude. Figure 30. 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, RCOMP and CCOMP 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, CCOMP will be typically a 100 nF capacitor and RCOMP 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. 22/31 Doc ID 8120 Rev 7 TSH512 General description The monostable holds the TSH512 in transmit mode during a delay fixed by the value of CTRIG connected to pin 29. 1.4V VOX DELAY = ⎛ ----------- ⎞ ⋅ C trig ⎝ 5 μA ⎠ 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 31. VOX state at power-on on POWER SUPPLY off high state if retriggered by audio 1 VOX -MUTE 0 time VOX Delay (Ctrig) Doc ID 8120 Rev 7 23/31 General description TSH512 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 consists in a high-pass filter in order to compensate the behavior of the FM transmission. Figure 32. Pre-emphasis schematics RPEA1 and CPEA1 set the time constant of the pre-emphasis as: τ = RPEA1. CPEA1 50 µs or 75 µs time constants are generally used. Choosing the gain of the PEA stage also allows one to set the right modulation level to the varicap diode. The gain in the passband is: GPEA = 1+ (RPEA2/RPEA1) 24/31 Doc ID 8120 Rev 7 TSH512 General description 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 Table 1 for the usual frequencies in infrared audio. The working frequency is: 1 f VCO = -------------------------------2 π ( L ⋅ Ct ) where Ct is the total capacity of CL, Cp, Cs and Cv: Ct = 1/(1/Cc+1/CL) with Cc = Cp+1/(1/Cv+1/Cs) It is possible to use varicap diodes SMV1212 (Alpha Ind.) or ZC833 (Zetex). Table 5. Usual infrared frequencies IR frequency in MHz 1.6 1.7 2.3 2.8 Applications AM mono FM mono FM right channel FM left channel or mono 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. Doc ID 8120 Rev 7 25/31 General description TSH512 5.8 Output buffer section The output buffers can deliver a sinusoidal signal with a 1.5 Vpp amplitude in a 1 kΩ 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 Standby pin (SBY) sets the second transmitter TX2 to power-down. The SBY pin is typically used when the TSH512 is used as a mono transmitter (that is, infrared microphone transmitter). 26/31 Doc ID 8120 Rev 7 TSH512 Package information 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. Doc ID 8120 Rev 7 27/31 Package information TSH512 6.1 TQFP44 package information Figure 34. TQFP44 package mechanical drawing Table 6. TQFP44 package mechanical data Dimensions Ref. Min. A A1 A2 b c D D1 D3 E E1 E3 e L L1 K ccc 0° 0.45 11.80 9.80 0.05 1.35 0.30 0.09 11.80 9.80 Millimeters Typ. Max. 1.6 0.15 1.40 0.37 1.45 0.45 0.20 12 10.00 8.00 12.00 10.00 8.00 0.80 0.60 1.00 3.5° 7° 0.10 0° 0.75 0.018 12.20 10.20 0.465 0.386 12.20 10.20 0.002 0.053 0.012 0.004 0.465 0.386 Min. Inches Typ. Max. 0.063 0.006 0.055 0.015 0.057 0.018 0.008 0.472 0.394 0.315 0.472 0.394 0.315 0.031 0.024 0.039 3.5° 7° 0.004 0.030 0.480 0.402 0.480 0.402 28/31 Doc ID 8120 Rev 7 TSH512 Ordering information 7 Ordering information Table 7. Order codes Temperature range Package TQFP44 -40° C to +85°C TQFP44 (automotive grade level) Packing Tray Tape & reel Tape & reel Marking TSH512C TSH512CYF Part number TSH512CF TSH512CFT TSH512CYFT(1) 1. Qualification and characterization according to AEC Q100 and Q003 or equivalent, advanced screening according to AEC Q001 & Q 002 or equivalent. Doc ID 8120 Rev 7 29/31 Revision history TSH512 8 Revision history Table 8. Date 08-Aug-2001 Document revision history Revision 1 Changes First release corresponding to preliminary data version of datasheet. Datasheet updated for Maturity 30: – ESD sensitive device sentence added – 4 curves updated – Electrical parameters updated Specific content changes as follows: – Application diagrams updated – Releases on curves – Application schematic diagram update – Electrical parameters updated 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. PPAP reference inserted in the datasheet, see order codes table. Document reformatted with minor text changes. Added footnote for automotive grade order codes to order codes table. Added data at -40° C < Tamb < +85° C in Table 4. Updated package mechanical drawing in Chapter 6: Package information. 09-Sep-2001 2 01-Dec-2003 3 01-Apr-2005 4 14-Oct- 2005 13-Nov-2007 5 6 28-May-2009 7 30/31 Doc ID 8120 Rev 7 TSH512 Please Read Carefully: Information in this document is provided solely in connection with ST products. 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The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners. © 2009 STMicroelectronics - All rights reserved STMicroelectronics group of companies Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan Malaysia - Malta - Morocco - Philippines - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America www.st.com Doc ID 8120 Rev 7 31/31