TSH346IDT

TSH346 Triple video buffer/filter for HD video applications Features ■ ■ ■ ■ ■ ■ ■ ■ ■ 6th order filtering of 36 MHz 5 V single-supply operation Internal input DC level shifter No input capacitor required Three matched 6 dB amplifiers AC or DC output-coupled Very low harmonic distortion Specified for 150 Ω loads Minimum and maximum data is tested during production R in 1 Pin1 identification SO-8 (plastic package) Top View 36MHz LPF + + + 6dB 8 R out Applications ■ ■ ■ ■ G in 2 36MHz LPF 6dB 7 G out High-end video systems High definition TV (HDTV) Broadcast and graphic video Multimedia products +VCC 4 B in 3 36MHz LPF 6dB 6 B out DC Shifter 5 GND Description The TSH346 is a triple single-supply video buffer featuring an internal gain of 6 dB and a 36 MHz filtering for HD video outputs on 75-Ω video lines. The TSH346 is ideal to drive either YUV, YPbPr or RGB signals from video DAC outputs. The main advantage of this circuit is that its input DC level shifter allows for video signals on 75-Ω video lines without damaging the synchronization tip of the video signal, and with no input capacitor, while using a single 5 V power supply. The DC level shifter is internally fixed and optimized to keep the output video signals between low and high output rails. This level is as low as possible to minimize the output DC level in the video line. The TSH346 is available in an SO-8 plastic package for optimum space saving. December 2008 Rev 2 1/18 www.st.com 18 Absolute maximum ratings and operating conditions TSH346 1 Table 1. Symbol VCC Vin Toper Tstd Tj Rthjc Rthja Pmax. ESD Absolute maximum ratings and operating conditions Absolute maximum ratings (AMR) Parameter Supply voltage (1) Input voltage range (2) Value 6 2.5 -40 to +85 -65 to +150 150 28 150 1 500 2 100 Unit V V °C °C °C °C/W °C/W W V kV V Operating free air temperature range Storage temperature Maximum junction temperature SO8 thermal resistance junction to case SO8 thermal resistance junction to ambient area Maximum power dissipation (at Tamb = 25° C) for Tj = 150° C CDM: charged device model HBM: human body model MM: machine model 1. All voltage values, except the differential voltage, are with respect to the network terminal. 2. The magnitude of the input and output voltages must never exceed VCC +0.3 V. Table 2. Symbol VCC Operating conditions Parameter Power supply voltage Value 4.5 to 5.5 (1) Unit V 1. Tested in full production with a +5 V single power supply. 2/18 TSH346 Electrical characteristics 2 Table 3. Symbol Electrical characteristics VCC = +5 V single supply, Tamb = 25° C (unless otherwise specified) Parameter Test conditions Min. Typ. Max. Unit DC performance VDC Output DC shift RL = 150 Ω Tamb , -40° C < Tamb < +85° C Input bias current Input resistance Input capacitance No load, input to GND ICC Total supply current -40° C < Tamb < +85° C DC voltage gain RL = 150 Ω, Vin = 0.5 V -40° C < Tamb < +85° C Output characteristics VOH VOL High level output voltage Low level output voltage Isource IOUT Isink Filtering Small signal, VICM = 0.5 V, RL = 150 Ω -3 dB bandwidth -1 dB bandwidth Small signal, F = 74.25 MHz VICM = 0.5 V, RL = 150 Ω RL = 150 Ω -40° C < Tamb < +85° C RL = 150 Ω 76 -40° C < Tamb < +85° C 106 -40° C < Tamb < +85° C 3.4 3.9 V 3.8 47 100 91 mA 134 126 mV 1.96 45 2 1.96 2.05 V/V Tamb , input to GND -40° C < Tamb < +85° C 100 240 310 1.3 1.4 1 0.1 44.6 51.6 mA 3.6 μA MΩ pF 440 mV Iib Rin Cin G Bandwidth High definition Attenuation D Noise eN Total input voltage noise Delay between each channel 25 25 36 32 32 0.5 MHz dB ns F = 100 kHz, RIN = 50 Ω 86 nV/√ Hz 3/18 Electrical characteristics TSH346 Figure 1. 10 Filtering Figure 2. 6.2 Gain flatness 0 6.0 Filter response (dB) -10 Filter response (dB) Vcc=5V small signal Load=150Ω 10M 100M 5.8 -20 5.6 -30 -40 5.4 Vcc=5V small signal Load=150 Ω 1M 10M -50 1M 5.2 Frequency (Hz) Frequency (Hz) Figure 3. 0 -10 -20 Distortion 1 MHz (HD) Figure 4. 0 -10 -20 Distortion 10 MHz (HD) Vcc=5V F=1MHz Load=150 Ω Vcc=5V F=10MHz Load=150 Ω HD2 & HD3 (dBc) -40 -50 -60 -70 -80 HD3 -90 -100 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 HD2 HD2 & HD3 (dBc) -30 -30 -40 -50 -60 -70 -80 -90 -100 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 HD3 HD2 Output Amplitude (Vp-p) Output Amplitude (Vp-p) Figure 5. 1000 Input noise vs. frequency Vcc=5V No load Figure 6. -40 Channel crosstalk vs. frequency -45 Input: 1Vp-p Vcc=5V Load=150Ω Input Noise (nV/VHz) -50 Gain (dB) 100 100 1k 10k 100k 1M -55 -60 -65 -70 -75 1M 10M 100M Frequency (Hz) Frequency (Hz) 4/18 TSH346 Electrical characteristics Figure 7. 2.10 Gain vs. input amplitude Figure 8. 5.0 4.5 4.0 Output vs input amplitude Vcc=5V Load=150Ω 2.05 Vcc=5V Load=150Ω VOH 3.5 Gain (V/V) 2.00 Vout (V) 3.0 2.5 2.0 1.5 1.95 1.0 0.5 Output DCshift 1.90 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0.0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Vin (Vp-p) Vin (V) Figure 9. 50 Current consumption vs. supply Figure 10. Supply current vs. temperature 50 49 48 47 Vcc=5V no Load 40 Vcc=5V no Load Icc (mA) 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Icc (mA) 30 46 45 44 43 20 10 42 41 0 0.0 40 -40 -20 0 20 40 60 80 Vcc (V) Temperature (°C) Figure 11. 60 55 Filtering vs. temperature Figure 12. Filter attenuation vs. temperature 60 Vcc=5V Load=150Ω 55 50 Vcc=5V Load=150Ω -1dB Bandwidth (MHz) 50 45 40 35 30 25 20 -40 Attenuation (dB) 45 40 35 30 25 20 -40 HD, f=74.25MHz -20 0 20 40 60 80 -20 0 20 40 60 80 Temperature (°C) Temperature (°C) 5/18 Electrical characteristics TSH346 Figure 13. Gain matching vs. temperature 5 Figure 14. Output DC shift vs. temperature 400 375 350 325 Vcc=5V Load=150 Ω 4 Vcc=5V Load=150Ω 3 DCshift (mV) -20 0 20 40 60 80 300 275 250 225 200 175 MG (%) 2 1 150 125 0 -40 100 -40 -20 0 20 40 60 80 Temperature (°C) Temperature (°C) Figure 15. Isink vs. temperature 150 140 Figure 16. Isource vs. temperature 120 110 130 120 110 100 90 80 70 60 60 50 -40 100 Isource (mA) Isink (mA) 90 80 70 Vcc=5V -20 0 20 40 60 80 50 -40 Vcc=5V -20 0 20 40 60 80 Temperature (°C) Temperature (°C) Figure 17. 2.0 1.8 1.6 Ibias vs. temperature Figure 18. VOH vs. temperature 4.00 Vcc=5V 3.95 3.90 1.4 Ibias (μA) VOH (V) 1.2 1.0 0.8 0.6 3.85 3.80 3.75 3.70 0.4 0.2 0.0 -40 3.65 3.60 -40 Vcc=5V Load=150Ω -20 0 20 40 60 80 -20 0 20 40 60 80 Temperature (°C) Temperature (°C) 6/18 TSH346 Electrical characteristics Figure 19. VOL vs. temperature 60 Figure 20. Gain vs. temperature 2.20 2.15 55 2.10 50 2.05 2.00 1.95 1.90 35 VOL (mV) 45 40 Vcc=5V Load=150Ω -20 0 20 40 60 80 Gain (dB) 1.85 1.80 -40 Vcc=5V Load=150Ω -20 0 20 40 60 80 30 -40 Temperature (°C) Temperature (°C) 7/18 Power supply considerations and improvement of the PSRR TSH346 3 Power supply considerations and improvement of the PSRR Correct power supply bypassing is very important to optimize performance in low and highfrequency ranges. Bypass capacitors should be placed as close as possible to the IC pin (pin 4) to improve high-frequency bypassing. A capacitor (CLF) greater than 10 µF is necessary to improve the PSRR in low frequencies. For better quality bypassing, a capacitor of 100 nF (CHF) can be added. CHF must be placed as close as possible to the IC pin, to improve the noise supply rejection in the higher frequency ranges. A coil can be added in order to better reject the noise from the supply and to prevent current peaks as much as possible. Figure 21. Circuit for power supply bypassing +VCC Coil CLF + CHF 4 R G B 5 TSH346 AM00824 8/18 TSH346 Power supply considerations and improvement of the PSRR Figure 22. Circuit for noise rejection improvement measurement S R +5 V T- bias Coil + CLF AGILENT 4395A CHF 50 TSH346 50 A AM00825 Figure 23 shows how the power supply noise rejection evolves versus frequency depending on how carefully the power supply decoupling is achieved. Figure 23. Power supply noise rejection 0 -10 Noise rejection ratio (dB) -20 -30 -40 -50 -60 -70 -80 10k Vcc=5V(dc)+0.2Vp-p(ac) Decoupling capacitor: 10µF+100nF Load=150Ω Noise rejection=20 log (ΔVCC/ΔVout) no coil coil=560µH 100k 1M 10M 100M Frequency (Hz) 9/18 Using the TSH346 to drive YC, CVBS, YUV, YPbPr and RGB video components TSH346 4 Using the TSH346 to drive YC, CVBS, YUV, YPbPr and RGB video components Figure 24. Implementation of the video driver on output video DACs +5 V Reconstruction filtering LPF 1 Vpp 2 Vpp + + + 6 dB Y Video DAC 75 75 cable 1 Vpp 75 TV Pb Video DAC 0. 0.7 Vpp Reconstruction filtering LPF + + + 6 dB 75 75 cable 0.7 Vpp 75 1. 1.4 Vpp Pr Video DAC 0. 0.7 Vpp Reconstruction filtering LPF + + + 6 dB 75 75 cable 0.7 Vpp 75 TSH346 GND -5 V 1. 1.4 Vpp AM00826 10/18 TSH346 Using the TSH346 to drive YC, CVBS, YUV, YPbPr and RGB video components Figure 25. Shapes of HD video signals coming from DACs including the synchronization tip (Y signal) White (100IRE) 54 ns (4t) 27 ns (2t) 27 ns (2t) Image content 590 ns (44 t) 300 mV Black (30IRE) 300 mV GN D 590 ns (44 t) 14.8 us (110 0t): 1 920/1080i 24.3 us (180 0t): 1280/720i s yn c.t ip •F cl ock=74.25 MHz •t= 1/ Fclock = 13.5 ns AM00827 The TSH346 is used to drive high definition video signals up to 30 MHz. It can drive components such as YPbPr and RGB where the bottom of the signal is close to zero volts. An internal input DC value is added to the video signal in order to shift the bottom from GND. The shift is not based on the average of the signal, but is an analog summation of a DC component to the video signal. Therefore, no input capacitors are required. This provides a real advantage in terms of cost and board space. Under these conditions, it is possible to drive the signal in single supply with no saturation of the driver against the lower rail. Because half of the signal is lost through output impedance matching, in order to correctly drive the video line the shifted signal is multiplied by a gain of +2 or +6 dB. 11/18 Using the TSH346 to drive YC, CVBS, YUV, YPbPr and RGB video components Figure 26. Flexible solution for SD and HD signals TSH346 HD DAC +5V R 150Ω 75Ω TV Cable 75Ω DAC G B 150Ω 75Ω Cable 75Ω DAC TSH346 SO8 75Ω Cable RCA SCART 75Ω 150Ω SD DAC +5V R-G-B, Y-C-CVBS 75Ω Y,G 150Ω Cable 75Ω DAC Pb,B,C Pr,R,CVBS 150Ω 150Ω 75Ω Cable 75Ω DAC TSH173 TSH103 SO8 75Ω Cable 75Ω SD CVBS DAC 150Ω +5V Y-C 75Ω TSH122 SC70 Cable 75Ω CVBS 12/18 TSH346 Using the TSH346 to drive YC, CVBS, YUV, YPbPr and RGB video components 4.1 Output capacitor The output can be either DC- or AC-coupled, and can be directly connected to the line via a 75-Ω resistor (4) (Figure 27). Alternatively, an output capacitor can be used to remove any DC components in the load. Assuming a 150-Ω load, a coupling capacitor of 220 µF can be used to provide a very low cut-off frequency close to 5 Hz (Figure 28). Figure 27. IDC output coupling (1 of 3 channels) +5V Video DAC 150 75 TSH346 75 75 cable AM00828 Figure 28. AC output coupling (1 of 3 channels) +5V Video DAC 150 CS 75 TSH346 C = 220 µF 75 + cable 75 AM00829 1. CS is a 100 nF used to decrease the parasitic components of C in high frequencies. 2. The 75-Ω resistor must be as close as possible to the output of the driver to minimize the effect of parasitic capacitance. 13/18 Package information TSH346 5 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. 14/18 TSH346 Figure 29. SO-8 package mechanical drawing Package information Table 4. SO-8 package mechanical data Dimensions Ref. Min. A A1 A2 b c D E E1 e h L L1 k ccc 0 0.25 0.40 0.10 1.25 0.28 0.17 4.80 5.80 3.80 Millimeters Typ. Max. 1.75 0.25 0.004 0.049 0.48 0.23 4.90 6.00 3.90 1.27 0.50 1.27 1.04 8° 0.10 1° 0.010 0.016 5.00 6.20 4.00 0.011 0.007 0.189 0.228 0.150 Min. Inches Typ. Max. 0.069 0.010 0.019 0.010 0.193 0.236 0.154 0.050 0.020 0.050 0.040 8° 0.004 0.197 0.244 0.157 15/18 Ordering information TSH346 6 Ordering information Table 5. Order codes Temperature range -40°C to +85°C Package SO-8 Packing Tube Tape & reel Marking TSH346I TSH346I Part number TSH346ID TSH346IDT 16/18 TSH346 Revision history 7 Revision history Table 6. Date 29-May-2007 16-Dec-2008 Document revision history Revision 1 2 Initial release. Added curves in Chapter 2: Electrical characteristics. Added all test limits in Table 3. Changes 17/18 TSH346 Please Read Carefully: Information in this document is provided solely in connection with ST products. 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