TSH344I(2006) 查看數據表（PDF） - STMicroelectronics

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TSH344I
(Rev.:2006)

340MHz Single-Supply Triple Video Buffer

STMicroelectronics 

TSH344

Using the TSH344 to Drive RGB Video Components

Figure 28 shows a schematic diagram of the use of the TSH344 to drive video output from

DACs.

The TSH344 is used to drive high definition video signals up to 30MHz on 75-ohm video

lines. It is dedicated to driving RGB signals typically between 300mV and 1V, as seen in (1).

With a very low output rail (VOL) guaranteed in test of production at 60mV maximum, it is

possible to drive the signal in single supply without any saturation of the driver against the

lower rail.

Assuming that we lose half of the signal by output impedance-matching in order to properly

drive the video line, the shifted signal is multiplied by a gain of 2 or +6dB (3).

4.1

Delay between channels

Figure 29. Measurement of the delay between each channel

5V

+6dB

75Ω

75Ω Cable

V1

75Ω

Vin

75Ω

+6dB

75Ω

75Ω Cable

V2

75Ω

+6dB

75Ω

75Ω Cable

V3

75Ω

Delay between each video component is an important aspect in high definition video

systems. To drive porperly the three video components without any relative delay, the dice of

the TSH344 is layouted out with a very symetrical geometry. The effect is direct on the

synchronization of each channel, as shown in Figure 30. No delay appears between each

channel when the same Vin signal is applied on the three inputs. Note that the delay from

the inputs the outputs equals 4ns.

Rev. 2

11/14

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