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

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

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

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

< +85° C

amb

<+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

< +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

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

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

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

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