AD9833 - Not oscillating 300mv O/P

Hi,

I've pretty much copied the UG-272 schematic and made a board up, but when testing I just get a static 300mV output.

On power up there's 300mV, drops down to about 100mV, then down to 0V and back to 300mV.

I've followed the AN-1070 and followed their basic example to create a 400Hz sine wave. I'm using CCS compiler on a dspic33, below are some snip-its:

// SPI Config

#USE SPI (DI=PIN_F7, DO=PIN_F8, CLK=PIN_F6, ENABLE=PIN_B2, MSB_FIRST, STREAM=AD9833, ENABLE_ACTIVE=0, MODE=1, BAUD=400000, BITS=16) 

// setup sinewave

spi_xfer(AD9833, 0x2100, 16);
delay_ms(2000);
spi_xfer(AD9833, 0x50C7, 16);
delay_ms(200);
spi_xfer(AD9833, 0x4000, 16);
delay_ms(200);
spi_xfer(AD9833, 0xC000, 16);
delay_ms(200);
spi_xfer(AD9833, 0x2000, 16);

Here's my schematic, my oscillator is 16MHz so I'm not expecting to get 400Hz as per the app note. Oscillator running fine, 3V3 present and I've examined the SPI data which is correct, the only thing left to try is replace the IC, any ideas what's wrong anyone please?

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    •  Analog Employees 
    on Aug 2, 2018 3:34 PM
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin
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  • 0
    •  Analog Employees 
    on Aug 2, 2018 3:34 PM
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin
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