AD8190ACPZ-R7 datasheet(13/24 Pages) AD

13 / 24 page

AD8190

Rev. 0 | Page 13 of 24

SWITCHING MODE

The AD8190 behaves like a 2:1 HDMI/DVI switch by imple-

menting a quad switching mode. In this mode, the user selects

the high speed source (A or B) that is routed to the output by

programming the HS_CH bit of the high speeds modes register

as shown in Table 7. The low speed auxiliary source (AUX_A or

AUX_B) that is routed to the common output is separately set

by programming the AUX_CH bit of the auxiliary device

AUXILIARY LINES SWITCHING

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

Showing AUX_A0 to AUX_COM0 Routing

When turning off the AD8190, care needs to be taken with

the AMUXVCC supply to ensure that the auxiliary multiplexer

pins are 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

AD8190. 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, regardless of the

state of the AD8190 and any downstream circuit. For this

configuration, the auxiliary inputs of the powered down

AD8190 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 AD8190 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 AD8190.

PERIPHERAL

CIRCUITRY

PERIPHERAL

CIRCUITRY

10kΩ

10MΩ

AD8190

AMUXVCC

+5V INTERNAL

(IF ANY)

10kΩ

I < 50mA

PIN 18 HDMI CONNECTOR

PIN 14 DVI CONNECTOR

PIN 18 HDMI CONNECTOR

PIN 14 DVI CONNECTOR

+5V

SOURCE A

SOURCE B

Figure 28. Suggested AMUXVCC Power Scheme

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