This technique works with any GreenPAK. The accuracy of the oscillator and CNT/DLY blocks vary from part-to-part.

GreenPAK ICs, like all chips with internal oscillators, have inherent variation in timing. This is attributed to factors like manufacturing, temperature and, in the case of GreenPAK, user design practices. By using simple design rules, the accuracy of counters and delays within a GreenPAK design can be improved.

应考虑振荡器和CNT / DLLY块之间的关系。振荡器是全球振荡器;它们可以用于任何数量的CNT / DLLY块，并且不会最初与延迟或计数器的开始/停止同步。因此，当启用计数器或延迟时，它只开始在下一个时钟边缘上递增。这在图9中描绘，其中延迟的使能信号被激活中间时钟周期，并且在下一个上升沿之前不会开始递减。

图9延迟升高的行为

This is factored into the typical delay time calculation for the CNT/DLY blocks:

因此，随着“反_DATA”的值增加，“T”对延迟时间的影响将较少。另外，延迟时间的绝对值可以保持相同，尽管使用更大的“计数器_Data”值，如果使用更快的“时钟”值。在里面Propertieswindow of the selected CNT/DLY block both the计数数据value and the clock source can be modified.

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