AD8190 Analog Devices, AD8190 Datasheet - Page 13

• Manufacturer Part Number: AD8190
• Description: 2:1 HDMI/DVI Switch with Equalization Data Sheet (Rev. 0, 8/2006)
• Manufacturer: Analog Devices

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
register as shown in Table 9.
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 I
connection is shown in Figure 27.
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
Figure 27. Auxiliary Channel Simplified Schematic
Showing AUX_A0 to AUX_COM0 Routing
2
AUX_A0
C. The schematic equivalent for this passive
½C
AUX
R
AUX
½C
AUX_COM0
AUX
Rev. 0 | Page 13 of 24
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.
SOURCE B
SOURCE A
PIN 18 HDMI CONNECTOR
PIN 18 HDMI CONNECTOR
PIN 14 DVI CONNECTOR
PIN 14 DVI CONNECTOR
Figure 28. Suggested AMUXVCC Power Scheme
+5V
+5V
PERIPHERAL
PERIPHERAL
CIRCUITRY
CIRCUITRY
I < 50mA
I < 50mA
10kΩ
10kΩ
10MΩ
AMUXVCC
+5V INTERNAL
(IF ANY)
AD8190
AD8190