© 2009 Fairchild Semiconductor Corporation

www.fairchildsemi.com

FMS6144A • Rev. 1.0.2

10

The same method can be used for biased signals, with

the addition of a pull-up resistor to make sure the clamp

never operates. The internal pull-down resistance is

800kΩ ±20%, so the external resistance should be

7.5MΩ to set the DC level to 500mV.

LCVF

Bias

Input

0.1μ

External video

source must

be AC coupled

500mV +/-350mV

75Ω

7.5MΩ

75Ω

Figure 18. Biased SCART with DC-Coupled Outputs

The same circuits can be used with AC-coupled outputs

if desired.

DVD or

STB

SoC

DAC

Output

75Ω

LCVF

Clamp

Active

0.1μ

0V - 1.4V

220μ

Figure 19. DC-Coupled Inputs, AC-Coupled Outputs

DVD or

STB

SoC

DAC

Output

LCVF

Clamp

Active

0.1μ

0V - 1.4V

75Ω

220μ

Figure 20. AC-Coupled Inputs and Outputs

LCVF

Clamp

Active

0.1μ

External video

source must

be AC coupled

0V - 1.4V

220μ

75Ω

75Ω

Figure 21. Biased SCART with AC-Coupled Outputs

NOTE: The video tilt or line time distortion is dominated

by the AC-coupling capacitor. The value may need to be

increased beyond 220μF to obtain satisfactory operation

in some applications.

Power Dissipation

The output drive configuration must be considered when

calculating overall power dissipation. Care must be taken

not to exceed the maximum die junction temperature. The

following example can be used to calculate the power

dissipation and internal temperature rise.

(1)

where:

(2)

and

(3)

where:

(4)

(5)

Board layout can also affect thermal characteristics.

Refer to the Layout Considerations section for details.

The FMS6144A is specified to operate with output

currents typically less than 50mA, more than sufficient

for a dual (75Ω) video load. Internal amplifiers are

current limited to a maximum of 100mA and should

withstand brief-duration short-circuit conditions. This

capability is not guaranteed.