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QS5LV919

3.3V LOW SKEW CMOS PLL CLOCK DRIVER WITH INTEGRATED LOOP FILTER

Integrated Device Technology 

QS5LV919

3.3V LOW SKEW CMOS PLL CLOCK DRIVER WITH INTEGRATED LOOP FILTER

BOARD VCC

INDUSTRIAL TEMPERATURE RANGE

10µ F

Low

Freq.

Bypass

0.1µ F

High

Freq.

Bypass

ANALOG VCC

DIGITAL

VCC

ANALOG GND

DIGITAL

GND

0.1µ F

Bypass

BOARD GND

A separate Analog power supply is not necessary

and should not be used. Following these pre-

scribed guidelines is all that is necessary to use

the QS5LV919 in a norm al digital environment.

Figure 1. Recommended Analog Isolation Scheme for the QS5LV919

NOTES:

1. Figure 1 shows an analog isolation scheme which will be effective in most applications. The following guidelines should be followed to ensure stable and jitter-free operation:

a. All analog isolation components should be tied as close to the package as possible. Stray current passing through the parasitics of long traces can cause undesirable voltage

transients.

b. The 10µF low frequency bypass capacitor and the 0.1µF high frequency bypass capacitor form a wide bandwidth filter that will minimize the QS5LV919's sensitivity to voltage

transients from the system digital VCC supply and ground planes.

If good bypass techniques are used on a board design near components which may cause digital VCC and ground noise, VCC step deviations should not occur at the QS5LV919's

digital VCC supply. The purpose of the bypass filtering scheme shown in figure 1 is to give the QS5LV919 additional protection from the power supply and ground plane

transients that can occur in a high frequency, high speed digital system.

2. The bypass capacitors can be ceramic chip capacitors. There should be a 0.1µF bypass capacitor between each of the other (digital) four VCC pins and the board ground plane.

This will reduce output switching noise caused by the QS5LV919 outputs, in addition to reducing potential for noise in the "analog" section of the chip. These bypass capacitors

should also be tied as close to the QS5LV919 package as possible.

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