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TA0310

Notes on video line driving

Implementation of TSH11x family in single supply 0/+5V:

Cin-R3 behaves like a high pass input filter (fc=16Hz) and removes the original DC component of the

video signal to create a "floating" signal. The R1-R2 resistor divider provides the new DC component. The

minimum level of that DC component must be ½VOL max (tested value). In order to limit the current

through R1 and R2, the value of these resistances must be sufficiently high. The maximum values of R1

and R2 are calculated to in order to arrive at +Ibias max (see datasheet) equal to 1% of the current

through R1 and R2. Cout removes the DC component to go back to the original video signal to fit with TV

requirements.

Figure 9: Implementation of the TSH11x in single supply 0/+5V

video line

75

Ω

75

Ω

680

Ω

+

-

+5V

TSH11x

0V

+5V

+

1µ

10n

Addition of a

new DC

component

(220µ)

R3

1k

1Vpp

0Volt

R1

R2

Twice the DC component (2Vdc)

0Volt

5Volt

Rail of TSH11x : +1.2V max (tested)

680

Ω

2

R

1

R

2

R

Vcc

Vdc

+

×

=

1Vpp

0Volt

Removes the

original DC

component

Removes the DC

component

Fc<5Hz

5V

0V

1Vp-p

Signal on the line

300mV