ADV3000 datasheet(13/28 Pages) AD

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ADV3000

Rev. 0 | Page 13 of 28

The ADV3000 requires output termination resistors when the

high speed outputs are enabled. Termination can be internal

and/or external. The internal terminations of the ADV3000

are enabled by programming the TX_PTO bit of the transmitter

settings register. These terminations are always enabled in

parallel control mode.

External terminations can be provided either by on-board

resistors or by the input termination resistors of an HDMI/

DVI receiver. If both the internal terminations are enabled and

external terminations are present, set the output current level to

20 mA by programming the TX_OCL bit of the transmitter

settings register through the serial control interface or by setting

the PP_OCL pin of the parallel control interface. The output

current level defaults to the level indicated by PP_OCL upon

reset. If only external terminations are provided (if the internal

terminations are disabled), set the output current level to 10 mA

by programming the TX_OCL bit of the transmitter settings

interface. The high speed outputs must be disabled if there are

no output termination resistors present in the system.

The output pre-emphasis can be manually configured to provide

one of four different levels of high frequency boost. The specific

boost level is selected by programming the TX_PE bits of the

transmitter settings register through the serial control interface,

or by setting the PP_PE bus of the parallel control interface. No

specific cable length is suggested for a particular pre-emphasis

setting because cable performance varies widely between

manufacturers.

AUXILIARY SWITCH

The auxiliary (low speed) lines have no amplification. They are

routed using a passive switch that is bandwidth compatible with

standard speed I2C. The schematic equivalent for this passive

connection is shown in Figure 27.

AUX_COM0

AUX_A0

½CAUX

RAUX

Figure 27. Auxiliary Channel Simplified Schematic,

AUX_A0 to AUX_COM0 Routing Example

When turning off the ADV3000, care needs to be taken with

the AMUXVCC supply to ensure that the auxiliary multiplexer

pins remain in a high impedance state. A scenario that illustrates

this requirement is one where the auxiliary multiplexer is used

to switch the display data channel (DDC) bus. In some applica-

tions, additional devices can be connected to the DDC bus

(such as an EEPROM with EDID information) upstream of

the ADV3000. Extended display identification data (EDID)

is a VESA standard-defined data format for conveying display

configuration information to sources to optimize display use.

EDID devices may need to be available via the DDC bus, regard-

less of the state of the ADV3000 and any downstream circuit.

For this configuration, the auxiliary inputs of the powered

down ADV3000 need to be in a high impedance state to avoid

pulling down on the DDC lines and preventing these other

devices from using the bus.

When the ADV3000 is powered from a simple resistor network,

as shown in Figure 28, it uses the 5 V supply that is required

from any HDMI/DVI source to guarantee high impedance of

the auxiliary multiplexer pins. The AMUXVCC supply does not

draw any static current; therefore, it is recommended that the

resistor network tap the 5 V supplies as close to the connectors

as possible to avoid any additional voltage drop.

This precaution does not need to be taken if the DDC

peripheral circuitry is connected to the bus downstream of

the ADV3000.

PERIPHERAL

CIRCUITRY

+5V SOURCE C

PIN 18 HDMI CONNECTOR

PIN 14 DVI CONNECTOR

10kΩ

10MΩ

I<50mA

PERIPHERAL

CIRCUITRY

PERIPHERAL

CIRCUITRY

SOURCE A +5V

SOURCE B +5V

PIN 18 HDMI CONNECTOR

PIN 14 DVI CONNECTOR

PIN 18 HDMI CONNECTOR

PIN 14 DVI CONNECTOR

10kΩ

I<50mA

AMUXVCC

ADV3000

+5V INTERNAL

(IF ANY)

Figure 28. Suggested AMUXVCC Power Scheme

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