Output Capacitor Selection

For applications utilizing the LP2994 to terminate SSTL-2 I/O

signals the typical application circuit shown in

Figure 12 can

be implemented.

This circuit permits termination in a minimum amount of

board space and component count. Capacitor selection can

be varied depending on the number of lines terminated and

the maximum load transient. However, with motherboards

and other applications where V

plane it is advisable to use multiple bulk capacitors and

addition to high frequency decoupling.

Figure 13 shown

below depicts an example circuit where 2 bulk output capaci-

tors could be situated at both ends of the V

optimal placement. Large aluminum electrolytic capacitors

are used for their low ESR and low cost.

In most PC applications an extensive amount of decoupling

is required because of the long interconnects encountered

20045911

FIGURE 11. Creating a Reference Voltage for Memory and Chipsets

20045912

FIGURE 12. Typical SSTL-2 Application Circuit

20045913

FIGURE 13. Typical SSTL-2 Application Circuit for Motherboards

www.national.com

13