Datasheet

ADV7127
–14– REV. 0
Power Planes
The PC board layout should have two distinct power planes,
one for analog circuitry and one for digital circuitry. The analog
power plane should encompass the ADV7127 (V
AA
) and all
associated analog circuitry. This power plane should be con-
nected to the regular PCB power plane (V
CC
) at a single point
through a ferrite bead, as illustrated in Figure 25. This bead
should be located within three inches of the ADV7127.
The PCB power plane should provide power to all digital logic
on the PC board, and the analog power plane should provide
power to all ADV7127 power pins, voltage reference circuitry
and any output amplifiers.
The PCB power and ground planes should not overlay portions
of the analog power plane. Keeping the PCB power and ground
planes from overlaying the analog power plane will contribute to
a reduction in plane-to-plane noise coupling.
Supply Decoupling
Noise on the analog power plane can be further reduced by the
use of multiple decoupling capacitors (see Figure 25).
Optimum performance is achieved by the use of 0.1 µF ceramic
capacitors. Each of the two groups of V
AA
should be individually
decoupled to ground. This should be done by placing the ca-
pacitors as close as possible to the device with the capacitor
leads as short as possible, thus minimizing lead inductance.
It is important to note that while the ADV7127 contains cir-
cuitry to reject power supply noise, this rejection decreases with
frequency. If a high frequency switching power supply is used,
the designer should pay close attention to reducing power sup-
ply noise. A dc power supply filter (Murata BNX002) will pro-
vide EMI suppression between the switching power supply and
the main PCB. Alternatively, consideration could be given to
using a three terminal voltage regulator.
GND
R
SET
I
OUT
GROUND
ADV7127
C3
0.1mF
C5
0.1mF
R1
75V
C1
33mF
C2
10mF
COMP
C6
0.1mF
ANALOG POWER PLANE
L2 (FERRITE BEAD)
D0
D9
CLOCK
VIDEO
DATA
INPUTS
ANALOG GROUND PLANE
C4
0.1mF
L1 (FERRITE BEAD)
V
AA
V
REF
+5V (V
CC
)
R
SET
560V
COMPONENT DESCRIPTION VENDOR PART NUMBER
C1 33mF TANTALUM CAPACITOR
C2 10mF TANTALUM
C3, C4, C5, C6 0.1mF CERAMIC CAPACITOR
L1, L2 FERRITE BEAD FAIR-RITE 274300111 OR MURATA BL01/02/03
R1 75V 1% METAL FILM RESISTOR DALE CMF-55C
R
SET
560V 1% METAL FILM RESISTOR DALE CMF-55C
VIDEO
OUTPUT
PSAVE
PDOWN
Figure 25. Typical Connection Diagram and Component List