TDA8784 Datasheet, PDF (22/28 Pages) NXP Semiconductors – 18 Msps, 10-bit analog-to-digital interface for CCD cameras

Philips Semiconductors
18 Msps, 10-bit analog-to-digital
interface for CCD cameras
Product specification
TDA8784
Power and grounding recommendations
When designing a printed-circuit board for applications
such as PC cameras, surveillance cameras, camcorders
and digital still cameras, care should be taken to minimize
the noise.
For the front-end integrated circuit, the basic rules of
printed-circuit board design and implementation of
analogue components (such as classical operational
amplifiers) must be respected, particularly with respect to
power and ground connections.
The following additional recommendation is given for the
CDS input pin(s) which is/are internally connected to the
programmable gain amplifier:
• The connections between CCD interface and CDS input
should be as short as possible and a ground ring
protection around these connections can be beneficial.
Separate analogue and digital supplies provide the best
solution. If it is not possible to do this on the board then
the analogue supply pins must be decoupled effectively
from the digital supply pins. If the same power supply
and ground are used for all the pins then the decoupling
capacitors must be placed as close as possible to the IC
package.
• In a two-ground system, in order to minimize the noise
though package and die parasitics, the following
recommendations must be implemented:
– All the analogue and digital supply pins must be
decoupled to the analogue ground plane. Only the
ground pin associated with the digital outputs must be
connected to the digital ground plane. All the other
ground pins should be connected to the analogue
ground plane. The analogue and digital ground
planes must be connected together at one point as
close as possible to the ground pin associated with
the digital outputs.
– The digital output pins and their associated lines
should be shielded by the digital ground plane which
can be used then as return path for digital signals.
1999 Sep 21
22