V

OS

GND

FerriteBead

1 µF

10µF

0.1 µF(x6)

Board

Supply

Chip

Supply

CDCLVD1212

SCAS901B – SEPTEMBER 2010 – REVISED JANUARY 2011

www.ti.com

TYPICAL CHARACTERISTICS (continued)

Figure 11. Output AC Common Mode

APPLICATION INFORMATION

THERMAL MANAGEMENT

For reliability and performance reasons, the die temperature should be limited to a maximum of 125°C.

The device package has an exposed pad that provides the primary heat removal path to the printed circuit board

(PCB). To maximize the heat dissipation from the package, a thermal landing pattern including multiple vias to a

ground plane must be incorporated into the PCB within the footprint of the package. The thermal pad must be

soldered down to ensure adequate heat conduction to of the package. Check the mechanical data at the end of

the data sheet for land and via pattern examples.

POWER SUPPLY FILTERING

High-performance clock buffers are sensitive to noises on the power supply, which can dramatically increase the

additive jitter of the buffer. Thus, it is essential to reduce noise from the system power supply, especially when

jitter/phase noise is critical to the application.

Filter capacitors are used to eliminate the low-frequency noise from the power supply, where the bypass

capacitors provide the very low impedance path for high-frequency noise and guard the power-supply system

against the induced fluctuations. These bypass capacitors also provide instantaneous current surges as required

by the device and should have low equivalent series resistance (ESR). To properly use the bypass capacitors,

they must be placed close to the power-supply pins and laid out with short loops to minimize inductance. It is

recommended to add as many high-frequency (for example, 0.1 mF) bypass capacitors as there are supply pins

in the package. It is recommended, but not required, to insert a ferrite bead between the board power supply and

the chip power supply that isolates the high-frequency switching noises generated by the clock driver; these

beads prevent the switching noise from leaking into the board supply. Choose an appropriate ferrite bead with

low dc resistance because it is imperative to provide adequate isolation between the board supply and the chip

supply, as well as to maintain a voltage at the supply pins that is greater than the minimum voltage required for

proper operation.

Figure 12. Power Supply Filtering

10

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