Input Interfacing — Control Inputs

(Continued)

FE is normally conditioned in one of three ways.

1.

FE tied high. This is the most common mode for FE. In

this mode, when a TRS is received, PCLK is aligned to

the new TRS. If a new sync position (NSP) is identified,

the NSP output will go high until the next TRS is re-

ceived.

2.

FE tied to NSP. When in this mode, if a TRS that is out

of phase with the existing PCLK is detected, NSP will go

high, but the phase of PCLK will not be adjusted. If the

next TRS received is in-phase with PCLK, NSP will go

low and the decoder will continue without changing its

state. If the next TRS to arrive is out of phase with PCLK,

then PCLK’s phase is adjusted to meet the new TRS

and NSP is made low. Single erroneous TRS pulses are

ignored in this mode, but if they persist, the decoder will

re-adjust PCLK to properly frame the data.

3.

FE held low during active video. The automatic fram-

ing feature using the TRS may be disabled in cases

where non-SMPTE 259M signals are being processed.

In some applications like computer-generated anima-

tion, the serial video data may not adhere to the SMPTE

259M standard and patterns that resemble TSR’s can

occur within the active video line. When such patterns

occur and to prevent the CLC011 from attempting re-

framing, make FE a logic low during the active video

line.

Output Interface — Output Logic

Levels

All outputs of the CLC011 are CMOS compatible. They can

be programmed to provide appropriate output logic levels to

connect to following stages operating from supplies of 3.0V

to 5.5V. Output voltages are set by applying the positive sup-

ply voltage powering the following stage to VDP, which con-

trols PD0-9, EAV, TRS and NSP, and VCP, which controls

PCLK. An example of the CLC011, powered from +5V, driv-

ing a device powered from a 3.3V supply is shown in

Figure

5.

The CLC011’s output drivers, shown simplified in

Figure 6,

are designed to maintain a constant, controlled slew rate re-

gardless of load. This design results in lower output switch-

ing noise injection via the supply pins and into other circuitry.

Even so, it is recommended that the CLC011 and other digi-

tal circuitry be separated from analog circuitry and cable

equalizers.

DS100086-7

FIGURE 5. Typical Output Interface

DS100086-8

FIGURE 6. Simplified Output Buffer Schematic

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