ST TSH122 User Manual

Ultra low power video buffer/filter with power-down

Features

■ Very low consumption: 1.7 mA

■ Ultra low power-down mode: 4 nA typ.,

500 nA max.

■ Internal 6

■ Internal gain of 6 dB

■ Rail-to-rail output buffer for 75 Ω video line

■ Excellent video performance

– Differential gain 0.5%
– Differential phase 0.10°
– Group delay of 10 ns

■ SAG correction

■ Bottom of video signal close to 0 V

■ Tested with 2.5 V and 3.3 V single supply

■ Data min. and max. are physically tested and

guaranteed during production (consumption,
gain, filtering, and other parameters are
guaranteed)

th

order reconstruction filter

IN

IN

GND

GND

SAG

SAG

TSH122

SC70

Top view

Top view

6

1

1

2

2

3

3

6

Vcc

Vcc

EN (enable)

EN (enable)

5

5

OUT

OUT

4

4

Applications

Description

■ Mobile phones

■ Digital still camera

■ Digital video camera

■ Portable DVD players

August 2008 Rev 1 1/16

The TSH122 is a video buffer that uses a voltage
feedback amplifier, with an internal gain of 6 dB,
an output rail-to-rail, an internal input DC-shift and
a SAG correction. A power-down function allows
switching to a sleep mode with an ultra-low
consumption.

The TSH122 features a 6th-order internal
reconstruction filter to attenuate the parasitic
frequency of 27 MHz from the clock of the video
DAC.

The TSH122 operates from 2.25 to 5 V single
power supplies and is tested at 2.5 V and 3.3 V.

The TSH122 is a single operator available in a
tiny SC70 plastic package for space saving.

www.st.com

16

Absolute maximum ratings and operating conditions TSH122

1 Absolute maximum ratings and operating conditions

Table 1. Absolute maximum ratings

Symbol Parameter Value Unit

V

CC

V

T

T

R

thja

R

thjc

Supply voltage

Maximum input amplitude 0 to Vcc V

in

Storage temperature -65 to +150 °C

stg

Maximum junction temperature 150 °C

j

SC70 thermal resistance junction to ambient area 205 °C/W

SC70 thermal resistance junction to case 172 °C/W

Maximum power dissipation for Tj=150°C

P

max

T
T

amb

amb

= +25°C
= +85°C

CDM: charged device model

ESD

HBM: human body model
MM: machine model

Output short-circuit

1. All voltage values, except differential voltage, are with respect to network terminal.

2. Charged device model: all pins and the package are charged together to the specified voltage and then
discharged directly to the ground through only one pin. This is done for all pins.

3. Human body model: a 100 pF capacitor is charged to the specified voltage, then discharged through a

1.5 kΩ resistor between two pins of the device. This is done for all couples of connected pin combinations
while the other pins are floating.

4. Machine model: a 200 pF capacitor is charged to the specified voltage, then discharged directly between
two pins of the device with no external series resistor (internal resistor < 5 Ω). This is done for all couples of
connected pin combinations while the other pins are floating

5. An output current limitation protects the circuit from transient currents. Short-circuits can cause excessive
heating. Destructive dissipation can result from short-circuits on amplifiers.

Table 2. Operating conditions

(1)

(4)

(3)

(2)

5.5 V

609

mW

317

1.5

1.5

300

(5)

kV
kV

V

Symbol Parameter Value Unit

V

CC

T

oper

1. Tested in full production at 0 V/2.5 V and 0 V/3.3 V single power supply.

Power supply voltage 2.25 to 5

Operating free air temperature range -40 to +85 °C

2/16

(1)

V

TSH122 Electrical characteristics

2 Electrical characteristics

Table 3. VCC = +2.5V, +3.3V, T

= 25°C (unless otherwise specified)

amb

Symbol Parameter Test conditions Min. Typ. Max. Unit

DC performance

V

I

Output DC level shift RL = 150Ω 70 115 168 mV

dc

= +3.3V -1.5 -0.87

V

CC

Input bias current

ib

V
T

min

= +3.3V,

CC

≤ T

amb

≤ T

max

-0.93

Vin=0V to 1V DC, VCC=+2.5V 5.8 6 6.1

=0V to 1.4V DC, VCC=+3.3V 5.8 6 6.1

V

G Internal voltage gain

PSRR

I

CC

Power supply rejection ratio
20 log (ΔV

CC

/ΔV

Positive supply current
DC consumption

out

)

in

=3.3V

V

CC

≤ T

T

ΔV

min

CC

≤ T

amb

=±100mV at 1kHz

Vin=+0.5V DC

=0V, no load

V

in

=+3.3V

V

CC

VCC=+2.5V

=+3.3V

V

CC

≤ T

T

min

amb

≤ T

max

max

5.96

55 dB

2

1.7

2.4

2.1

2.4 mA

Dynamic performance and output characteristics

μA

dB

mA

Small signal
V

=+3.3V, RL = 150Ω

CC

BW Filter bandwidth

-3dB bandwidth

-1dB bandwidth 5.4

9.5

7.2
MHz

-1dB bandwidth

FR 27 MHz rejection

= +3.3V,

V

CC

T

≤ T

amb

≤ T

min

Small signal
V

=+3.3V, RL=150Ω

CC

= +3.3V,

V

CC

≤ T

T

min

amb

≤ T

max

max

6.75

36 47 dB

46 dB

ΔG Differential gain VCC=+3.3V, RL=150Ω 0.5 %

ΔΦ Differential phase V

Gd Group delay V

V

High level output voltage

OH

=+3.3V, RL=150Ω 0.1 °

CC

=+3.3V, 10kHz-5MHz 6 ns

CC

V

=+3.3V, RL=150Ω

CC

VCC=+2.5V, RL=150Ω

3.1

2.3

3.2

2.4

V

3/16

Electrical characteristics TSH122

Table 3. VCC = +2.5V, +3.3V, T

= 25°C (unless otherwise specified) (continued)

amb

Symbol Parameter Test conditions Min. Typ. Max. Unit

V

I

out

Low level output voltage RL = 150Ω 11 40 mV

OL

Output short circuit current VCC=+2.5V 75 mA

Noise and distortion

eN Total output noise F = 100kHz, no load 51 nV/√Hz

=+3.3V, RL = 150Ω

V

CC

=1V

HD Harmonic distortion

V
H2
H3

in

, F=1MHz

p-p

64
61

Enable/power-down
Low level on pin-5: TSH122 in power-down
High level on pin-5: TSH122 enabled

I

V

V

high

T

T

Consumption in power-down

sd

mode

Low-level threshold 0 +0.3 V

low

High-level threshold +0.7

Time from power-down to enable 1 μs

on

Time from enable to power-down 1 μs

off

=+3.3V 4 500 nA

V

CC

V

CC

dBc

V

4/16

TSH122 Electrical characteristics

Figure 1. Frequency response Figure 2. Gain flatness

10

0

-10

-20

-30

-40

Gain (dB)

-50

Vcc=3.3V

-60

Load=150

-70

Small signal
Vicm=0.5V

-80
1M 10M 100M

Ω

Frequency (Hz)

6.2

6.1

6.0

5.9

5.8

5.7

5.6

Flatness (dB)

5.5

5.4

5.3

5.2
1M 10M

Vcc=+5V

Frequency (Hz)

Figure 3. Input noise Figure 4. Distortion

250

200

150

No load
Input to GND
Vcc=+2.5V and +3.3V

5

Load=150Ω

4

3

Vcc=+2.5V

Vcc=+3.3V

Vcc=+5V

Vcc=+3.3V

100

(nV/VHz)

n

e

50

0

100 1k 10k 100k 1M

Frequency (Hz)

2

Vout (V)

1

0

0.0 0.5 1.0 1.5 2.0 2.5

Vin (V)

Figure 5. Distortion at Vcc=2.5 V Figure 6. Distortion at Vcc=3.3 V

Vcc=+2.5V

-30

Vcc=2.5V
Load=150

-40

-50

-60

-70

Distortion (dB)

-80

-90

-100

0.0 0.5 1.0 1.5 2.0 2.5

Ω

H2

H3

Output Amplitude (Vp-p)

-30

Vcc=3.3V
Load=150

-40

-50

-60

-70

Distortion (dB)

-80

-90

-100

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Ω

H2

H3

Output Amplitude (Vp-p)

5/16