HCF4089B

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APPLICATION NOTES

For words of more than 4 bits, HCF4089B device may be cascaded in two different modes : an ADD mode

and a MULTIPLY mode.

TWO HCF4089B’S CASCADED IN THE "ADD" MODE WITH A PRESET NUMBER OF 189

In the ADD mode some of the gaps left by the more significant unit at the count of 15 are filled in by the less significant units. For example,

when two units are cascaded in the ADD mode and programmed to 11 and 13, respectively, the more significant unit will have 11 output

pulses and the other unit will have 13 output pulses for every 256 input pulses for a total of :

11

13

189

 +  = 

16

256

256

TWO HCF4089B’S CASCADED IN THE "MULTIPLY" MODE FOR MULTIPLICATION OF TWO

VARIABLES A AND B WITH LOOP CIRCUIT CONTROL

A

B

1

N

When the loop stabilities rate R2 = rate R3, thus fclock(

 • ) = fclock ( • ) therefore N = AB

16

16

16

16