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AD9954 Clock multiplier

Question asked by abdou on Apr 18, 2011
Latest reply on May 16, 2011 by DSB

Hi,

 

I'm using an ad9954 to output 122MHz as in the exemple in the datasheet. I want first ensure that the dds acceipt intruction byte and data word. So I write to the adresse 0x01 thid data 0x0000A4. I'm using a 20 MHz crystal as refclk, so according to my programming word SYNC_CLK should be at 100MHz , but no it is juste at 5MHz. Clearly the dds doesn't use the multiplier factor and I don't know what could be reason.

 

I send data from a fpga using the same clock as the sclk of the dds. In my process, I set the reset pin and send in MSB format the word 0x010000A4 and at the and I set io_update pin but nothing's happened. I use a design looks like the one attached( it's a design for ad9951EP).

 

Could you tell me please what should ? 

 

Regards!

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