AD8197-EVAL Analog Devices, AD8197-EVAL Datasheet - Page 29

• Manufacturer Part Number: AD8197-EVAL
• Description: 4:1 HDMI/DVI Switch with Equalization
• Manufacturer: Analog Devices

Preliminary Data Sheet
Power Supplies
The AD8197 has five separate power supplies referenced to
two separate grounds. The supply/ground pairs are:
•
•
•
•
•
The AVCC/AVEE (3.3 V) and DVCC/DVEE (3.3 V) supplies
power the core of the AD8197. The VTTI/AVEE supply (3.3 V)
powers the input termination (see Figure 25). Similarly, the
VTTO/AVEE supply (3.3 V) powers the output termination
(see Figure 26). The AMUXVCC/DVEE supply (3.3 V to 5 V)
powers the auxiliary multiplexer core and determines the
maximum allowed voltage on the auxiliary lines. For example,
if the DDC bus is using 5 V I
connected to +5 V relative to DVEE.
In a typical application, all pins labeled AVEE or DVEE should
be connected directly to ground. All pins labeled AVCC,
DVCC, VTTI, or VTTO should be connected to 3.3 V, and
Pin AMUXVCC tied to 5 V. The supplies can also be powered
individually, but care must be taken to ensure that each stage of
the AD8197 is powered correctly.
Power Supply Bypassing
The AD8197 requires minimal supply bypassing. When
powering the supplies individually, place a 0.01 μF capacitor
between each 3.3 V supply pin (AVCC, DVCC, VTTI, and
VTTO) and ground to filter out supply noise. Generally, bypass
capacitors should be placed near the power pins and should
connect directly to the relevant supplies (without long inter-
vening traces). For example, to improve the parasitic inductance
of the power supply decoupling capacitors, minimize the trace
length between capacitor landing pads and the vias as shown in
Figure 34.
AVCC/AVEE
VTTI/AVEE
VTTO/AVEE
DVCC/DVEE
AMUXVCC/DVEE
2
C, then AMUXVCC should be
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In applications where the AD8197 is powered by a single 3.3 V
supply, it is recommended to use two reference supply planes
and bypass the 3.3 V reference plane to the ground reference
plane with one 220 pF, one 1000 pF, two 0.01 μF, and one 4.7 μF
capacitors. The capacitors should via down directly to the
supply planes and be placed within a few centimeters of the
AD8197. The AMUXVCC supply does not require additional
bypassing. This bypassing scheme is illustrated in Figure 35.
Figure 35. Example Placement of Power Supply Decoupling Capacitors
Figure 34. Recommended Pad Outline for Bypass Capacitors
Around the AD8197
RECOMMENDED
NOT RECOMMENDED
EXTRA ADDED INDUCTANCE
AD8197