CX25870/871
3.0 PC Board Considerations
Flicker-Free Video Encoder with Ultrascale Technology
3.6 Applications Information
Figure 3-15. System Block Diagram for Graphics Card with TV Out
Graphics
BIOS
Flash ROM
AGP
Graphics
Controller
Analog RGB
Analog
RGB
SGRAM*8
or SDRAM*8
SYNC*s
CLKs
and
VGA Monitor
BLANK*
Digital RGB
or
YCrCB Pixels
Voltage
Regulator
CX25871
or
Bt869
DAC
Outputs
Conexant VGA Encoder
NTSC/PAL/SECAM
Television or HDTV
AGP Bus
100381_100
3.6.4 Electrostatic Discharge and Latchup Considerations
Correct electrostatic discharge (ESD)-sensitive handling procedures are required
to prevent device damage. Device damage can produce symptoms of catastrophic
failure or erratic device behavior with leaky inputs.
All logic inputs should be held low until power to the device has settled to the
specified tolerance. DAC power decoupling networks with large time constants
should be avoided; they could delay VAA and VDD power to the device. Ferrite
beads must be used only for analog power VAA decoupling. Inductors cause a
time-constant delay that induces latchup, and should not be substituted for a
ferrite bead.
Latchup can be prevented by ensuring that all VAA and VDD pins are at the
same potential and by forcing all AGND and VSS pins to be at the same potential.
The VAA and VDD supply voltage must be applied before the signal pin voltages.
The correct power-up sequence ensures that any signal pin voltage will never
exceed the power supply voltage.
100381B
Conexant
3-27
CONEXANT [ CONEXANT SYSTEMS, INC ]
