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Noise optimized layout of ADP1032

Hi all!

The ADP1032 is recommended to power the DAC AD5758. We're in search to improve the noise of this regulator. 

There is obviously an option to split SPI Ground and Power ground for ADP1032, since these gounds have separate pins at the IC. Is it possible to improve noise of the voltage regulator of ADP1032 with splitting these gounds?

Any advice for a workaround to improve the noise for voltage rail for the ADP1032 will be welcomed!

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  • Hi Dmitry,

    Thank you for using the ADP1032 and AD5758 in your application.

    I'm Jeff, the apps engineer for the ADP1032 and I need further informafion about your problem. Can you please provide more information about the noise you are trying to improve and how you configured your circuit to help me understand your problem. Do you know what frequency it might be (125khz? 250khz?, 500khz? or just random noise?). And by how much you want to improve it? Are you synchronizing the ADP1032 to AD5758 thru the SYNC/CLKOUT pin? Are you using the DPC function of the AD5758? Where do you get your SPI supply from VLDO output of the AD5758 or directly at VOUT2 of the ADP1032?

    As you know, the ADP1032 have 2 switching regulators and the AD5758 DPC is also a switching regulator that are inherently have output ripple, the flyback operates at 250khz and the buck operates at 125khz and the DPC operates at 500kHz, you can use an additional LC filter to reduce the ripple on these rails if you see these noise in the output. For the ADP1032 SPI, yes it would be better to split SPI ground from the power GND especially if you are using the VLDO of the AD5758 as the SPI supply. 

    Any further information about your problem would be great for me to understand it further and provide the best approach to solve it

    Thanks and regards,

    Jeff

Reply
  • Hi Dmitry,

    Thank you for using the ADP1032 and AD5758 in your application.

    I'm Jeff, the apps engineer for the ADP1032 and I need further informafion about your problem. Can you please provide more information about the noise you are trying to improve and how you configured your circuit to help me understand your problem. Do you know what frequency it might be (125khz? 250khz?, 500khz? or just random noise?). And by how much you want to improve it? Are you synchronizing the ADP1032 to AD5758 thru the SYNC/CLKOUT pin? Are you using the DPC function of the AD5758? Where do you get your SPI supply from VLDO output of the AD5758 or directly at VOUT2 of the ADP1032?

    As you know, the ADP1032 have 2 switching regulators and the AD5758 DPC is also a switching regulator that are inherently have output ripple, the flyback operates at 250khz and the buck operates at 125khz and the DPC operates at 500kHz, you can use an additional LC filter to reduce the ripple on these rails if you see these noise in the output. For the ADP1032 SPI, yes it would be better to split SPI ground from the power GND especially if you are using the VLDO of the AD5758 as the SPI supply. 

    Any further information about your problem would be great for me to understand it further and provide the best approach to solve it

    Thanks and regards,

    Jeff

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