AD9513 freq divide configuration


Hi. I am in the design of a pcb that uses the AD9513 as a freq divider.
For my application I need just one output for a freq divide by 10.

I made a configuration table according to the datasheet.
If I check the datasheet, table 14 indicates S5 and S6 divide for OUT2 when S2=2/3.
but it is also indicated in Table 16.

I am not sure how to use pins S9 and S10.
If I configured a divide by 10 with S5 and S6, what should I do with S9 and S10?

In this case will it divide by 10 or by 22? Do the pins have some priority over the others?

Thanks!


  • 0
    •  Analog Employees 
    on Jul 8, 2021 3:35 PM

    Hi,

    S0=0 is fine, because you do not want any delay to be introduced in OUT2.

    S1=S2=2/3 is fine, because you want only OUT2 to be CMOS and OUT0 and OUT1 to be off.

    S3=S4=0 is fine. The OUT2 phase offset is 0 (because S0=0, you use the OUT2 Phase column in Table 13).

    S5=0 and S6=2/3. Because S2=2/3, no column in Table 14 is used, so the setting of S5 and S6 does not matter, but you need to set them to certain values anyway.

    S7 and S8 in Table 15 refer to OUT1 Divide in Table 15 because S2=2/3, so it is not 1. You selected S7=0 and S8=2/3, which means OUT1 divide by 10 and 50 % duty cycle. Because OUT1 is off, the settings do not matter, but you need to set them to certain values anyway.

    S9 and S10 in Table 16 use the column OUT2 divide because S2=2/3. There is no setting to divide OUT2 by 10, so choosing S2=2/3 was not a good choice.

    From Table 14, we need to have S2=1/3 or S2=1 in order to use S5=1 and S6=2/3 to have OUT2 divide by 10 and 50% duty cycle.

    I propose to use S2=1, so OUT1 is off. Then you can use S1=0 or 1 because both situations have OUT2 as CMOS (it seemed to me you want OUT2 as CMOS).

    So:

    S0=0

    S1=0 or 1 and S2=1, which means OUT2 is enabled and CMOS. OUT0 is also enabled.

    S3=S4=0, so OUT2 phase is 0 (use OUT2 Phase column in Table 13 because S0=0).

    S5=0, S6=2/3 to have OUT2 divide by 10 with 50% duty cycle.

    S7 and S8 do not matter because S2=1 and S0=0, so we put them both to 0.

    S9=S10=0, so we use OUT0 Divide column in Table 16 because S2=1 is not 2/3, so OUT0 divide is 1.

    Petre 

  • Hi Petre thank you for your help.

    Yes indeed I need only one CMOS output and that’s why I chose S1=2/3 and S2=2/3. I think your solution will work fine. It activates OUT0 which I don’t need so I can just leave unused and use only OUT2.

    Anyway this made me review other possibilities and now I think I can get a better result using only OUT1.

    pin         voltage                function

    S0           0                             BYPASS

    S1           1                             OUT2 off; out0off; out1cmos

    S2           2/3                         OUT2 off; out0off; out1cmos

    s3           0                             OUT2 DELAY 0 don’t care

    s4           0                             OUT2 DELAY 0 don’t care

    S5           0                             OUT2 DIVIDE 10 don’t care because out2=off

    S6           2/3                         OUT2 DIVIDE 10 don’t care because out2=off

    S7           0                             OUT1 DIVIDE 10

    S8           2/3                         OUT1 DIVIDE 10

    S9           0                             OUT2 duty 43% don’t care

    S10         0                             OUT2 duty 43% don’t care

     

    Thank you very much for your help.