ADV7175A datasheet(38/52 Pages) AD

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ADV7175A/ADV7176A

–38–

REV. B

For external buffering of the ADV7175A/ADV7176A DAC outputs, the configuration in Figure 71 is recommended. This configu-

ration shows the DAC outputs running at half (18 mA) their full current (36 mA) capability. This will allow the ADV7175A/ADV7176A

to dissipate less power, the analog current is reduced by 50% with a RSET of 300

Ω and a R

LOAD of 75

Ω. This mode is recommended for

3.3 volt operation as optimum performance is obtained from the DAC outputs at 18 mA with a VAA of 3.3 volts. This buffer also

adds extra isolation on the video outputs, see buffer circuit in Figure 72. When calculating absolute output full current and voltage,

use the following equation:

VOUT

= I

OUT

× R

LOAD

IOUT

VREF

× K

()

RSET

= 4.2146 constant ,V

REF

= 1.235 V

ADV7175A/ADV7176A

VREF

DIGITAL

CORE

PIXEL

PORT

300

RSET

VAA

OUTPUT

BUFFER

DAC A

OUTPUT

BUFFER

OUTPUT

BUFFER

OUTPUT

BUFFER

DAC C

DAC D

DAC B

Figure 71. Output DAC Buffering Configuration

2N2907

OUTPUT TO

TV/MONITOR

INPUT

VCC

Figure 72. Recommended Output DAC Buffer

APPENDIX 7

OPTIONAL DAC BUFFERING

ADV7175A Datasheet(PDF) 38 Page - Analog Devices

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