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 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- 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- 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.
Sy mbol 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 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 , 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 -3 dB bandwidth -1 dB bandwidth Small signal, F = 74.25 MHz VICM = 0.5 V, RL = 150 RL = 150 -40 C < Tamb < +85 C RL = 150 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 A M 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
86
nV/ Hz
3/18
Electrical characteristics
TSH346
Figure 1.
10
Filtering
Figure 2.
6 .2
Gain flatness
0
6 .0
Filter response (dB)
-1 0
Filter response (dB)
V cc=5 V sm all signal Load=150
10M 1 00 M
5 .8
-2 0
5 .6
-3 0
-4 0
5 .4
V cc=5V s m a ll signal Load=150
1M 10 M
-5 0 1M
5 .2
Frequency (Hz)
F re q u e n c y (Hz)
Figure 3.
0 -10 -20
Distortion 1 MHz (HD)
Figure 4.
0 -10 -20
Distortion 10 MHz (HD)
Vcc=5V F= 1 MH z L o ad = 1 5 0
Vcc=5V F= 1 0 MH z L o a d =1 5 0
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= 5 V No load
Figure 6.
-40
Channel crosstalk vs. frequency
-45
Input: 1Vp-p V c c =5 V L oa d = 15 0
Input Noise (nV/VHz)
-50
Gain (dB)
100 100 1k 10k 100k 1M
-55
-60
-65
-70
-75 1M
10 M
10 0M
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 =150
2.05
Vcc=5V L o a d= 1 50
V OH
3 .5
Gain (V/V)
2.00
Vout (V)
3 .0 2 .5 2 .0 1 .5
1.95 1 .0 0 .5 O utput 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
V cc= 5 V 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 -4 0
-2 0
0
20
40
60
80
Vcc (V)
Tem perature (C)
Figure 11.
60 55
Filtering vs. temperature
Figure 12. Filter attenuation vs. temperature
60
Vcc=5V L o ad = 1 5 0
55 50
Vcc=5V L o a d =1 5 0
-1dB Bandwidth (MHz)
50 45 40 35 30 25 20 -4 0
Attenuation (dB)
45 40 35 30 25 20 -4 0
HD, f=74.25MHz
-2 0
0
20
40
60
80
-20
0
20
40
60
80
Tem perature (C)
Tem perature (C)
5/18
Electrical characteristics
TSH346
Figure 13. Gain matching vs. temperature
5
Figure 14. Output DC shift vs. temperature
400 375 350 325
V cc=5 V Load=150
4
V c c= 5 V L oa d= 1 50
3
DCshift (mV)
-2 0 0 20 40 60 80
300 275 250 225 200 175
M G (%)
2
1
150 125
0 -40
100 -4 0
-20
0
20
40
60
80
T em p er atur e (C)
Tem perature (C)
Figure 15. Isink vs. temperature
1 50 1 40
Figure 16. Isource vs. temperature
120
110 1 30 1 20 1 10 1 00 90 80 70 60 60 50 -40 100
Isource (mA)
Isink (mA)
90
80
70
V c c =5 V
-2 0 0 20 40 60 80 50 -4 0
Vcc=5V
-2 0 0 20 40 60 80
Tem perature (C)
Tem p erature (C)
Figure 17.
2.0 1.8 1.6
Ibias vs. temperature
Figure 18. VOH vs. temperature
4 .0 0
V c c=5 V
3 .9 5 3 .9 0
1.4
Ibias (A)
VOH (V)
1.2 1.0 0.8 0.6
3 .8 5 3 .8 0 3 .7 5 3 .7 0
0.4 0.2 0.0 -40 3 .6 5 3 .6 0 -4 0
V cc = 5 V Lo ad= 150
-2 0 0 20 40 60 80
-2 0
0
20
40
60
80
Tem perature (C)
Temperature (C)
6/18
TSH346
Electrical characteristics
Figure 19. VOL vs. temperature
60
Figure 20. Gain vs. temperature
2 .2 0 2 .1 5
55 2 .1 0 50 2 .0 5 2 .0 0 1 .9 5 1 .9 0 35
VOL (mV)
45
40
V c c= 5 V L o a d =1 5 0
-2 0 0 20 40 60 80
Gain (dB)
1 .8 5 1 .8 0 -4 0
V cc= 5V Load=150
-20 0 20 40 60 80
30 -40
Temperature (C)
Tem perature (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 F 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
Co il 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 5V
T - bias Coil + CLF AGILENT 4395A CHF
+ SH346 50 T
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 -1 0
Noise rejection ratio (dB)
-2 0 -3 0 -4 0 -5 0 -6 0 -7 0 -8 0 10 k
Vcc=5V(dc)+0.2Vp-p(ac) Decoupling capacitor: 10F+100nF Load =150 Noise rejection=20 log (VCC/Vout)
no coil
c o il= 5 6 0 H
10 0 k
1M
10M
1 0 0M
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 Vpp 2 Vpp + + + 6 dB
Y 1
Video DAC
75
5
cable
1 Vpp 5
TV
Pb
Video DAC 0.7 Vpp
Reconstruction filtering LPF + + + 6 dB
75
75
cable
0.7 Vpp 75
1.4 Vpp
Pr
Video DAC 0.7 Vpp
Reconstruction filtering LPF + + + 6 dB
5
75
cable
0.7 Vpp 75
TSH346
GND -5 V
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 (4 t ) 27 ns (2 t ) 27 ns (2 t ) Image content
590 ns (4 4 t )
300 mV Black (30IRE)
300 mV
GN D
590 ns (4 4 t )
14.8 us (110 0 t): 1920/1080i 24.3 us (180 0 t): 1280/720i
s y n c .t i p ·F cl o ck= 74.25 M Hz ·t= 1/ F cl o ck = 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
150
75
TV
Cable
75
DAC
G B
150
75
Cable
75
DAC
TSH346 SO8
75
Cable RCA SCART
75
150
SD
DAC
+5V
R-G-B, Y-C-CVBS
75
Y,G
150
Cable
75
DAC
Pb,B,C Pr,R,CVBS
150 150
75
Cable
75
DAC
TSH173 TSH103 SO8
75
Cable
75
SD CVBS
DAC
150
+5V
Y-C
75
TSH122 SC70
Cable
75
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- resistor (4) (Figure 27). Alternatively, an output capacitor can be used to remove any DC components in the load. Assuming a 150- load, a coupling capacitor of 220 F 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 V ideo DAC 150 75 TSH346 C 7 75
5 cable
AM00828
Figure 28. AC output coupling (1 of 3 channels)
+5V V ideo DAC 150 75 TSH346 = 220 F 75 + C S
cable
75
AM00829
1. CS is a 100 nF used to decrease the parasitic components of C in high frequencies. 2. The 75- 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 -40C to +85C 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. STMicroelectronics NV and its subsidiaries ("ST") reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST's terms and conditions of sale. Purchasers are solely responsible for the choice, selection and use of the ST products and services described herein, and ST assumes no liability whatsoever relating to the choice, selection or use of the ST products and services described herein. No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. If any part of this document refers to any third party products or services it shall not be deemed a license grant by ST for the use of such third party products or services, or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoever of such third party products or services or any intellectual property contained therein.
UNLESS OTHERWISE SET FORTH IN ST'S TERMS AND CONDITIONS OF SALE ST DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY WITH RESPECT TO THE USE AND/OR SALE OF ST PRODUCTS INCLUDING WITHOUT LIMITATION IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION), OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT. UNLESS EXPRESSLY APPROVED IN WRITING BY AN AUTHORIZED ST REPRESENTATIVE, ST PRODUCTS ARE NOT RECOMMENDED, AUTHORIZED OR WARRANTED FOR USE IN MILITARY, AIR CRAFT, SPACE, LIFE SAVING, OR LIFE SUSTAINING APPLICATIONS, NOR IN PRODUCTS OR SYSTEMS WHERE FAILURE OR MALFUNCTION MAY RESULT IN PERSONAL INJURY, DEATH, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE. ST PRODUCTS WHICH ARE NOT SPECIFIED AS "AUTOMOTIVE GRADE" MAY ONLY BE USED IN AUTOMOTIVE APPLICATIONS AT USER'S OWN RISK.
Resale of ST products with provisions different from the statements and/or technical features set forth in this document shall immediately void any warranty granted by ST for the ST product or service described herein and shall not create or extend in any manner whatsoever, any liability of ST.
ST and the ST logo are trademarks or registered trademarks of ST in various countries. Information in this document supersedes and replaces all information previously supplied. The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners.
2008 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 - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America www.st.com
18/18
|
