ST TSH345 User Manual
Features
■ Selectable 6th order filtering of 36 MHz,
18 MHz and 9 MHz
■ 5 V single-supply operation
■ Internal input DC level shifter
■ No input capacitor required
■ 3 matched 6 dB amplifiers
■ AC or DC output-coupled
■ Very low harmonic distortion
■ Specified for 150 Ω loads
■ Data min. and max. are tested during
production
Applications
■ High-end video systems
■ High definition TV (HDTV)
■ Broadcast and graphic video
■ Multimedia products
Description
TSH345
Triple video buffer with selectable filter
for HD and SD video applications
SO-14
TSSOP14
Fs0
R1 in
R2 in
G1 in
G2 in
B1 in
B2 in
+VCC
1
2
3
4
5
6
7
MUX
MUXMUX
36MHz
18MHz
9MHz
LPF
36MHz
18MHz
9MHz
LPF
36MHz
18MHz
9MHz
LPF
+
+
+
DC Shifter
6dB
6dB
6dB
14
13
12
11
10
Fs1
R out
G out
B out
Mux
9
GND
8
The TSH345 is a triple single-supply video buffer
featuring an internal gain of 6 dB and selectable
filtering for HD and SD video outputs on 75 Ω
video lines. The TSH345 is ideal to drive YC,
CVBS, YUV, YPbPr or RGB signals from video
DAC outputs.
The main advantage of this circuit is its input DC
level shifter. It allows driving video signals on 75 Ω
video lines without damaging the synchronization
tip and without input or output capacitors when
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 in the best position for the greatest linearity.
The TSH345 is available in SO-14 and TSSOP-14
plastic packages for optimum space saving.
December 2008 Rev 1 1/23
www.st.com
23
Absolute maximum ratings and operating conditions TSH345
1 Absolute maximum ratings and operating conditions
Table 1. Absolute maximum ratings
Symbol Parameter Value Unit
V
T
T
CC
V
oper
stg
T
Supply voltage
in
Input voltage range 2.5 V
Operating free air temperature range -40 to +85 °C
Storage temperature -65 to +150 °C
Maximum junction temperature 150 °C
j
(1)
6V
Thermal resistance junction to case
R
thjc
SO-14
TSSOP14
22
32
Thermal resistance junction to ambient area
R
thja
P
max
ESD
SO-14
TSSOP14
Maximum power dissipation (at T
SO-14
TSSOP14
CDM: charged device model
HBM: human body model
MM: machine model
=25°C) for Tj= 150° C
amb
125
110
1
1.1
250
2
100
°C/W
°C/W
W
V
kV
V
1. All voltage values, except differential voltage, are with respect to network terminal.
Table 2. Operating conditions
Symbol Parameter Value Unit
V
CC
1. Tested in full production with +5 V single power supply.
Power supply voltage 4.5 to 5.5
(1)
V
2/23
TSH345 Electrical characteristics
2 Electrical characteristics
Table 3. Electrical characteristics at VCC= +5 V single supply, T
(unless otherwise specified)
Symbol Test conditions Min. Typ. Max. Unit
DC performance
Output DC shift
V
DC
= 150 Ω, T
R
L
-40° C < T
Input bias current
I
ib
T
, input to GND
amb
-40° C < T
R
C
Input resistance, T
in
Input capacitance, T
in
Total supply current (3 x operators)
I
CC
No load, input to GND
-40°C < T
DC voltage gain
G
= 150Ω, Vin=1.4V
R
L
-40°C < T
Output characteristics
amb
amb
amb
amb
amb
< +85° C
< +85° C
amb
amb
<+85°C
<+85°C
100 240
44.64551.6 mA
1.96 2
1.96
=25°C
amb
440 mV
310
1.3
3.6 µA
1.4
1MΩ
0.1 pF
2.05 V/V
V
OH
V
OL
I
out
Filtering
Standard
definition
High level output voltage
= 150 Ω
R
L
-40° C < T
amb
< +85° C
Low level output voltage
RL= 150 Ω
I
source
T
amb
-40° C < T
I
sink
-40° C < T
amb
amb
< +85° C
< +85° C
Bandwidth
F1 selected, small signal, V
=0.5V, RL=150Ω
ICM
-3 dB bandwidth
-1 dB bandwidth
Attenuation
F1 selected/F=27 MHz, small signal, V
=150Ω
R
L
ICM
=0.5V,
3.4 3.9
3.8
47 mV
76 100
91
106 134
126
9
5
5.7
MHz
40 45 dB
V
mA
mA
3/23
Electrical characteristics TSH345
Table 3. Electrical characteristics at VCC= +5 V single supply, T
amb
=25°C
(unless otherwise specified) (continued)
Symbol Test conditions Min. Typ. Max. Unit
Bandwidth
Standard
definition
with
progressive
scanning
F2 selected, small signal, V
-3 dB bandwidth
-1 dB bandwidth
Attenuation
F2 selected/F = 54 MHz, small signal,
V
=0.5V, RL=150Ω
ICM
Bandwidth
F3 selected, small signal, V
High
definition
-3 dB bandwidth
-1 dB bandwidth
Attenuation
F3 selected/F = 74.25 MHz, small signal,
V
=0.5V, RL=150Ω
ICM
D Delay between each channel 0.5 ns
gd
Δg
ΔΦ
Group delay variation
F1 selected/F = 0 to 6 MHz
Differential gain
F1 selected/F = 6 MHz, R
Differential phase
F1 selected/F = 6 MHz, R
Noise
=0.5V, RL= 150 Ω
ICM
=0.5V, RL= 150 Ω
ICM
=150Ω
L
=150Ω
L
21
13
18
32 38 dB
36
25
32
25 32 dB
11 ns
0.38 %
0.5 °
MHz
MHz
Total input voltage noise in Standard Definition
F = 100 kHz, RIN=50Ω
eN
Total input voltage noise in High Definition
F = 100 kHz, R
IN
=50Ω
Standby mode
Total current consumption in standby mode
I
STBY
T
T
on
off
Fs1 = 1, Fs0 = 1
T
amb
-40° C < T
amb
< +85° C
Time from standby to active mode 5 µs
Time from active to standby mode 5 µs
Fs1, Fs0 and Mux features
V
V
high
low
High level 0.9 V
Low level 0.3 V
4/23
74
86
440
480
690
nV/√Hz
µA
TSH345 Electrical characteristics
Table 4. Filter and standby settings, VCC= +5 V single supply, T
(1)
Fs1
0 0 F3 Filtering for high definition (HD)
0 1 F2 Filtering for progressive video (PV)
1 0 F3 Filtering for standard definition (SD)
1 1 Standby TSH345 in standby mode
1. Fs1 and Fs0 pins must never be left floating.
Table 5. Mux settings, VCC= +5 V single supply, T
(1)
Mux
0 R1 G1 B1 Video1 selected
1 R2 G2 B2 Video2 selected
1. The MUX pin must never be left floating.
Fs0
(1)
Settings
amb
Settings
=25°C
amb
=25°C
5/23
Electrical characteristics TSH345
Figure 1. Filtering Figure 2. Gain flatness
10
0
-10
-20
SD
-30
HD
PV
Filter response (dB)
Vcc=5V
-40
small signal
Load=150
-50
1M 10M 100M
Ω
Frequency (Hz)
6.2
6.0
5.8
5.6
Filter response (dB)
5.4
5.2
Vcc=5V
small signal
Load=150
SD
Ω
1M 10M
Frequency (Hz)
Figure 3. Distortion 1 MHz (HD) Figure 4. Distortion 10 MHz (HD)
0
Vcc=5V
-10
F=1MHz
-20
HD filter
Load=150
-30
-40
-50
-60
-70
HD2 & HD3 (dBc)
-80
-90
-100
0.00.51.01.52.02.53.03.54.0
Ω
HD2
HD3
Output Amplitude (Vp-p)
0
Vcc=5V
-10
F=10MHz
-20
HD filter
Load=150
-30
-40
-50
-60
-70
HD2 & HD3 (dBc)
-80
-90
-100
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Ω
HD2
HD3
Output Amplitude (Vp-p)
HD
PV
Figure 5. Distortion 1 MHz (PV) Figure 6. Distortion 10 MHz (PV)
0
Vcc=5V
-10
F=1MHz
PV filter
-20
Load=150
-30
-40
-50
-60
-70
HD2 & HD3 (dBc)
-80
-90
-100
0.00.51.01.52.02.53.03.54.0
Ω
HD2
HD3
Output Amplitude (Vp-p)
6/23
0
Vcc=5V
-10
F=10MHz
PV filter
-20
Load=150
-30
-40
-50
-60
-70
HD2 & HD3 (dBc)
-80
-90
-100
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Ω
HD2
HD3
Output Amplitude (Vp-p)
TSH345 Electrical characteristics
Figure 7. Distortion 1 MHz (SD filter) Figure 8. Input noise vs. frequency
0
Vcc=5V
-10
F=1MHz
SD filter
-20
Load=150
-30
-40
-50
-60
-70
HD2 & HD3 (dBc)
-80
-90
-100
0.00.51.01.52.02.53.03.54.0
Ω
HD2
HD3
Output Amplitude (Vp-p)
1000
HD
PV
SD
100
Input Noise (nV/VHz)
100 1k 10k 100k 1M
Frequency (Hz)
Vcc=5V
No load
Figure 9. Gain vs. input amplitude Figure 10. Channel crosstalk vs. frequency
Gain (V/V)
2.10
2.05
2.00
1.95
Vcc=5V
Load=150
Ω
X-Talk (dB)
-40
-45
-50
-55
-60
-65
-70
Input: 1Vp-p
HD filter
Vcc=5V
Load=150
Ω
1.90
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
Vin (Vp-p)
-75
1M 10M 100M
Frequency (Hz)
Figure 11. Output vs input amplitude Figure 12. MUX isolation
5.0
Vcc=5V
4.5
Load=150
4.0
3.5
3.0
2.5
2.0
Vout (V)
1.5
1.0
0.5
0.0
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
Ω
Output DCshift
V
OH
Vin (V)
-40
Input: 1Vp-p
Vcc=5V
-45
Load=150
-50
-55
-60
-65
MUX isolation (dB)
-70
-75
1M 10M 100M
Ω
Frequency (Hz)
7/23
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