ICS674-01

User Configurable Divider

MDS 674-01 A

3

Revision 033199

Printed 11/15/00

Integrated Circuit Systems • 525 Race Street • San Jose • CA • 95126 •(408)295-9800tel•(408)295-9818fax

PRELIMINARY INFORMATION

Determining (setting) the divider

The user has full control in setting the desired divide. The user should connect the appropriate divider select

input pins directly to ground (or VDD, although this is not required because of internal pull-ups) during

Printed Circuit Board layout, so that the ICS674-01 automatically produces the correct divide when all

components are soldered. It is also possible to connect the inputs to parallel I/O ports in order to change

divides.

The divides of the ICS674-01 can be determined by the following simple equations:

Divide A = DAW+2

Where

Divider A Word (DAW) = 1 to 127 (0 is not permitted).

Divide B = (DBW+8)•PD

Where

Divider B Word (DBW) = 4 to 511 (0,1,2,3, are not permitted).

Post Divider (PD) = values on Page 2

For example, suppose Divide A is desired to be 61 and Divide B is desired to be 284, then

DAW = 59, DBW = 276 and PD = 1. This means A6:A0 is 0111011, B8:B0 is

100010100 and S2:S0 is 110. Since all inputs have pull-ups, it is only necessary to ground

the zero pins, namely A6, A2, B7, B6, B5, B3, B1, B0 and S0.