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
V
CC
V
in
T
oper
T
std
T
j
R
thjc
R
thja
P
max.
ESD
Absolute maximum ratings and operating conditions
Absolute maximum ratings (AMR)
Parameter
Supply voltage
(1)
Input voltage range
(2)
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 T
amb
= 25° C) for T
j
= 150° C
CDM: charged device model
HBM: human body model
MM: machine model
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
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 V
CC
+0.3 V.
Table 2.
Symbol
V
CC
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
V
CC
= +5 V single supply, T
amb
= 25° C (unless otherwise specified)
Parameter
Test conditions
Min.
Typ.
Max.
Unit
DC performance
V
DC
Output DC shift
R
L
= 150
Ω
T
amb
,
-40° C < T
amb
< +85° C
Input bias current
Input resistance
Input capacitance
No load, input to GND
I
CC
Total supply current
-40° C < T
amb
< +85° C
DC voltage gain
R
L
= 150
Ω,
V
in
= 0.5 V
-40° C < T
amb
< +85° C
Output characteristics
V
OH
V
OL
High level output voltage
Low level output voltage
I
source
I
OUT
I
sink
Filtering
Small signal, V
ICM
= 0.5 V,
R
L
= 150
Ω
-3 dB bandwidth
-1 dB bandwidth
Small signal, F = 74.25 MHz
V
ICM
= 0.5 V, R
L
= 150
Ω
R
L
= 150
Ω
-40° C < T
amb
< +85° C
R
L
= 150
Ω
76
-40° C < T
amb
< +85° C
106
-40° C < T
amb
< +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
T
amb
, input to GND
-40° C < T
amb
< +85° C
100
240
310
1.3
1.4
1
0.1
44.6
51.6
mA
3.6
μA
MΩ
pF
440
mV
I
ib
R
in
C
in
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, R
IN
= 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=150
Ω
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=150
Ω
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=150
Ω
2.05
Vcc=5V
Load=150
Ω
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
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=150
Ω
55
50
Vcc=5V
Load=150
Ω
-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
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