CDCE62005 registers' value

It's still me

I have another question:

What does the PORTS in the configure file mean?

for example,

PORTS
0 bf
1 ffffffff
2 ffffffff
3 ffffffff

Thank you

Nick

Hi Nick,

thank you for the interest in our device. I checked your register setting and I found out that you are using the external loop filter, which usually is not strickly needed for XTAL input case. I defined my register setting in order to get the same output frequencies and the lock condition as well. Please find them attached.

In order to get the lock condition I had to tune the loop filter. On the GUI you can use the Loop Filter Tool. Two parameters are important: the Loop Bandwidth and the Phase Margin. In case of XTAL input you can set a wide loopbandwidth. The Phase Margin should be in the range 60 to 70 degree. You can change these parameter by tuning C1, R2,C2, R3 and C3 values. You will see a direct impact on the output jitter performance.

If you need further detail, please do not hesitate to contact us.

Best regards,

Leandro

REGISTERS
0 eb060330
1 eb060331
2 eb840302
3 eb0e0303
4 10e03f4
5 10007b15
6 33ff83e6
7 fdfffff7
8 800098b8

PORTS
0 fd
1 ff
2 df
3 f9

INPUTS
PRI 0
SEC 0
AUX 25

EXTERNAL COMPONENTS
C4 1
R4 1
C5 1

Hi,Leandro

Thank you for your detailed reply.

I still have some problems with these registers. First, you mean I need to configure the internal loop filter to get right output frequency. But I don't quite sure how to

configure it. And what values of C1, R2,C2, R3 and C3 do I need?

What's more, what does the the following PORTS parameters mean?

PORTS
0 fd
1 ff
2 df
3 f9

Thank you

Nick

Hi Leandro,

Thanks a lot for your info. I have one more question, which is by reading the datasheet of CDCE62005, all registers have reserved bits. Some bits say they must be set to 0

and others say they must be set to 1. What do these  reserved bits mean? Do they have some real meaning? And do I have to do as what the datasheet says?

Thanks

Best regards

Nick

Hi Nick,

the reserved bits are either used by the state engine of the device or for internal test purpose.

If you use the GUI to generate the register setting for your application, you will realize that the content of the reversed bits matches with the indication on the datasheet. You should not modify them otherwise there will be an impact on the device functionality.

BTW, in which context/application are you using the CDCE62005?

Thanks and best regards,

Leandro

Hi Leandro,

You mean I should strictly follow what the datasheet says about the reserved bits. And do not change the value if the corresponding bit should be set to 0 or 1.

We use CDCE62005 to generate clock for DSP,FPGA and CPLD. And MSP430F5418A control CDCE62005 to do the above thing.

Thanks and best regards,

Nick

Hi Leandro,

Thank you very much. If I have some other question, I hope you can help me. I really appreciate your help.

Thanks

Best regards,

Nick

Hi Leandro,

I'm sorry to bother you again. I encounter another question when using CDCE62005:

There are 10 bits which is marked as read only int the 8th register of CDCE62005. At start up, I write all the registers to CDCE62005. If I write the read only bits, is there an

impact on the device? If there is, what should I do about those read only bits? To ignore them?

Best regards,

Thank you

Nick

Hi Nick,

the read-only bits on the register 8th can not be written. They can just be used to check what the device status is. Therefore if you write them, there should not be any impact on the device.

Best regards,

Leandro