INPUT INTERFACES

The CLC016 provides high impedance inputs which accept

differential or single-ended input drive. The detailed electri-

cal specifications are found in the Electrical Characteris-

tics page. Recommended interfaces for the CLC016 follow.

Four conditions should be observed when interfacing to the

CLC016 inputs:

•

Keep input levels within specified common-mode input

range.

•

Provide a bias current path to the inputs.

•

Terminate cable in the proper impedance.

•

Observe the output current requirements of the driving

device.

Figure 16 and Figure 17 show DC and AC coupled interface

examples which meet these four conditions.

OUTPUT INTERFACES

SDO, SDO, SCO, and SCO swing at ECL logic levels when

the correct external components are used. However, the

outputs are not standard emitter-coupled logic outputs. In-

stead, the signals flow from the collectors of the output

transistors. The primary advantage of this architecture is

lower power dissipation. Some example interfaces follow.

Differential Load-Terminated Output Interface

Figure 18 shows an interface to drive signals differentially

over a coaxial cable. The diode establishes V

resistor network sets V

in its characteristic impedance.

Differential Source-Terminated Output Interface

Figure 19 is similar to Figure 18 except that the termination

is placed near the output pins.

10008727

FIGURE 15. Output Timing of Clock and Data

10008728

FIGURE 16. Differential 75

Ω Source

10008729

FIGURE 17. AC Coupled Termination

10008730

FIGURE 18. Differential Load-Terminated

Output Interface

www.national.com

14