Toshiba TDP-D1, Service Manual

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Clocks and Phase Lock Loop (PLL)
Consider a PLL as a servo loop, such a person controlling the speed of a car with the accelerator.
As more people talk in the car (or other distractions that may occur) the more the person
instinctively attempts to block them out. In a sense, this shortens the loop between the mind and the
foot of the driver, thus reducing noise influences. The PLL needs this same type of attention to path
detail. The loop filter passive components must be kept as close to the VCO control pin as possible.
They can be placed on either side of the board as long as no noise producing components are in the
immediate vicinity.
Video Interface
This section provides design guidelines for the Video interface, and describes:
 Input Signals

 Power

 Clocks

 Output Signals

Input Signals
The AC-coupled video interface inputs may or may not need diodes, depending on the
requirements of the video decoder used. Keep these signals on the outside surfaces of board next to
the ground plane, as short as possible, and away from other signals.
Power
The critical power design considerations are:
 Isolate the power supplied to the analog portions of the video decoder f

rom the power supplied to
the digital portions of the circuit board.
 Isolate the power planes for the analog portions of the circuit board from the digital power plane,

although they all can be on the same layer.
 Use a linear regulator to supply thes

e voltages to reduce the risk of switching noise being present
on the pane.