CX25870/871
3.0 PC Board Considerations
Flicker-Free Video Encoder with Ultrascale Technology
3.2 Power and Ground Planes
Figure 3-2. Connection Diagram for Output Filters and Other Key Passive Components/Standard Definition TV Out Only
CX25870/871 Power Plane
+1.1 V to
+1.8 V
VAA
CX25870/871
FB
C7
C8
+3.3 V (VCC)
C2–C6
(1)
COMP
VBIAS
VDDL
+
C9
(1)
VDD_CO
C10
C1
VREF
Ground
(Power Supply
Connector)
10
KΩ
1%
GND
75 Ω, 75 Ω, 75 Ω, 75 Ω,
FSADJUST
(1)
RSET =
75 Ω,1%
1%
1%
1%
1%
VDD_VREF
10
KΩ
1%
P
P
P
P
DACA
DACB
DACC
SD LPF
SD LPF
SD LPF
SD LPF
To Video
Connector
DACD
XTALIN XTALOUT
:
P
13.500 MHz XTAL
(2)
VAA
SD LPF
(2)
27 pF
,
33 pF
5%
,
Schottky Diodes
To Filter
22 pF, 5%
5%
DAC Output
Schottky Diodes
1.8 µH, 5%
270 pF, 5%
GND
330 pF,
5%
Note(s):
(1)
VDDL VDD_CO, VDD_VREF must be tied to 3.3 V CX25870/871 Power Plane unless interface to low power graphics
controller is required.
(2)
(3)
Depending on the parasitic capacitance of your PCB and loading expectations of your crystals, these capacitor values
may change slightly. Generally, the 27 pF and 33 pF combination matches a 20 pF internal XTAL load.
No RF Modulator has been included on any of the DAC outputs. Baseband video is always generated by the CX25870.
100381_018a
100381B
Conexant
3-3
CONEXANT [ CONEXANT SYSTEMS, INC ]
