12.1 Layout Guidelines

In general, there are two cases for layout:

1. Use as a single PLL: In this case, all power supply pins must be connected, but for those on the unused PLL, bypassing is not necessary, and they can be shorted together. Leave unused outputs unconnected, and do not ground them.
2. Use as a dual PLL: In this case, supply coupling is much more critical as there can be crosstalk between the two PLLs. There must be isolation in the form of resistors or inductors between the charge-pump supply pins, and decoupling capacitors are more important.

12.2 Layout Example

Figure 36. Layout Example