AD8146ACPZ-R7 datasheet(17/24 Pages) AD

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AD8146/AD8147/AD8148

Rev. 0 | Page 17 of 24

–OUT R

+OUT R

–OUT G

+OUT G

–OUT B

+OUT B

VOCM WEIGHTING EQUATIONS:

RED VOCM = K(VSYNC – HSYNC) + VMIDSUPPLY

GREEN VOCM = K(–2VSYNC) + VMIDSUPPLY

BLUE VOCM = K(VSYNC + HSYNC) + VMIDSUPPLY

+IN R

–IN R

VSYNC

HSYNC

SYNC LEVEL

+IN G

–IN G

+IN B

–IN B

1kΩ

AD8147/AD8148

500Ω

1kΩ

500Ω

VOCM

VOCM B

1kΩ

500Ω

OPD

×2

Figure 30. AD8147/AD8148 Sync-On Common-Mode Encoding Scheme

0.5

1.0

1.5

2.0

4.0

3.5

4.5

2.5

3.0

5.0

0.98

0.99

1.00

1.01

1.03

1.04

1.05

1.02

1.06

1.07

TIME (µs)

HSYNC

VSYNC

2.0

2.1

2.2

2.3

2.4

2.9

2.8

3.0

2.5

2.6

2.7

3.1

Figure 31. AD8147 Sync-On Common-Mode Signals in Single 5 V Application

The transmitted common-mode sync signal magnitudes are

scaled by applying a dc voltage to the SYNC LEVEL input,

referenced to GND. The difference between the voltage applied

to the SYNC LEVEL input and GND sets the peak deviation of

the encoded sync signals about the midsupply, common-mode

voltage. For example, with the SYNC LEVEL input set at 500 mV,

the deviation of the encoded sync pulses about the nominal

midsupply, common-mode voltage is typically ±500 mV. The

equations in Figure 30 describe how the VSYNC and HSYNC signals

are encoded on each color’s midsupply common-mode signal.

In these equations, the weights of the VSYNC and HSYNC signals

are ±1 (+1 for high and −1 for low), and the constant K is equal

to the peak deviation of the encoded sync signals.

Figure 31 shows how the sync signals appear on each common-

mode voltage in a single 5 V supply application when the voltage

applied to the SYNC LEVEL input is 500 mV, which is the

typical setting for most applications.

AD8146ACPZ-R7 Datasheet(PDF) 17 Page - Analog Devices

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