Migrating from AD5724 to AD5724R

Question

Hello, We just started working with an updated design which now uses an AD5724R but it does not work properly. I cannot set output voltages, especially negative voltages, but the previous design which used an AD5724 with an external reference works just fine. How are the 2 parts different from a software perspective? Thank you for any insight or suggestions. Steve

ADIApproved · Accepted Answer

Hi Steve, 
 Have you checked the Internal Reference Section of the data sheet? According to the data sheet, the on-chip voltage reference is powered down by default. If an external voltage reference source is to be used, the internal reference must remain powered down at all times. If the internal reference is to be used as the reference source, it must be powered up via the PU_REF bit of the power control register. The internal reference voltage is accessible at the REFIN/REFOUT pin for use as a reference source for other devices within the system. If the internal reference is to be used external to the AD5724R/ AD5734R/AD5754R, it must first be buffered. 
 Regards, 
 Mark)

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Migrating from AD5724 to AD5724R