The required memory output enable access time is more complicated since it is affected by the clock doubler delays. The clock doubler setup register creates a nominal delay time ranging from 6 to 20 ns, resulting in a nominal clock low time ranging from 6 to 20 ns. The clock low time depends on internal delays, and is subject to variation arising from process variation, operating voltage and temperature. Minimum and maximum clock low times for various doubler settings are given in the formulas and in the graph below.

Max. delay @ 3.3 V = 6.1 + 1.21(n - 6) [n is the nominal delay, 6–20 ns)

Min. delay @ 3.3 V = 3.7 + 0.75(n - 6)

Max. delay @ 2.5 V = 7.6 + 1.67(n - 6)

Min. delay @ 2.5 V = 4.7 + 1.03(n - 6)

Max. delay @ 1.8 V = 12.2 + 2.7(n - 6)

Min. delay @ 1.8 V = 6.6 + 1.44(n - 6)

 

60.0

 

 

 

 

 

 

50.0

 

 

 

 

 

 

40.0

 

 

 

 

 

(ns)

30.0

 

 

 

 

 

Delay

 

 

 

 

 

 

 

 

 

 

 

 

20.0

 

 

 

 

 

 

10.0

 

 

 

 

 

 

0.0

 

 

 

 

 

 

0

5

10

15

20

25

Nominal Delay (ns)

3.3 V

2.5 V

1.8 V

Figure 16-5. Clock Doubler Max-Min Clock Low Times

User’s Manual

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Image 230
Jameco Electronics 3000, 2000 manual Clock Doubler Max-Min Clock Low Times