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Recommended 1.8V regulator for 8 DDS chips

Hi ,

I am using 8 DDS chips (AD9959) for one of my design. Please recommend a 1.8V regulator for the DDS chips.

It would be better if you suggest a single regulator which can supply all 8 Chips.

Thanks in advance,

Regards,

Prakash B J

  • Hi Prakash B J,

    You may want to check out the ADM7150 to supply the AVDD and DVDD pins of the AD9959.

    The ADM7150 has an accuracy of +/-2% across load (up to 800mA), line and temperature which is within the +/-5% requirement of the AVDD and DVDD pins.

    The ADM7150 also has a noise density of 1.7nV/rtHz from 10kHz to 1MHz which is very good for your noise sensitive application.

    I also want to ask where does the input of your LDO coming from?

    If the input of the LDO is coming from a switching regulator, the PSRR of the ADM7150 can help reduce the noise coming from the switching regulator. For a 400mA load (close to supply current needed by the AD9959), the PSRR is >60dB at 1MHz.

    regards,

    Rainier

  • Hi rrosario,

    I went through the datasheet of the part. Its maximum output current is 800mA.

    Is 800mA sufficient for all the 8 DDS chips?

    Regards,

    Prakash BJ


  • Hi Prakash BJ,

    The AVDD and DVDD supply pins of the AD9959 draws a maximum of 325mA when all channels are turned on.

    The 800mA maximum output current of the ADM7160 can only supply up to two DDS chips.

    There are higher current output LDOs such as the ADP1706/7/8 (1A), ADP3338/9(1A.1.5A) which you can use for more than three or four DDS chips respectively. The trade-off would be that you would have greater noise at the supply pins.

    Regards,

    Rainier

  • Hi rrosario ,

    I am going ahead with ADP3339 for my design.

    I am using one ADP3339 / 4 DDS(AD9959) chips.

    Thank you,

    Prakash

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