What is the AD5673R Channel Output Voltage?

Question

I can't believe I have to ask this here, but I can't seem to make sense of the datasheet. 
 On page 23 under "Output Amplifiers", the datasheet says that the outputs are rail to rail, or 0 to VDD. My VDD is 3.3V. How do I configure this device to produce 0-3.3V on the analog outputs? Is it even possible? 
 Can this device be used with an external reference? In table 1 on the first page, it looks like this device (16 channel, I2C) is hardwired to use an internal reference. However, elsewhere the internal reference is described as "default." On page 28, under Internal Reference Setup, DB0 is used to disable the internal reference. Can the internal reference be disabled on this device so that VREF (pin 21) can be used as an input for an external reference? 
 Thanks 
 Doug

EZAutoReply · Accepted Answer

Hi dougcl 
 dougcl said: On page 23 under "Output Amplifiers", the datasheet says that the outputs are rail to rail, or 0 to VDD. My VDD is 3.3V. How do I configure this device to produce 0-3.3V on the analog outputs? Is it even possible? 
 There are two ways to achieve this, 1) is with the internal 2.5V reference, ang gain = 2 setting, the output span would be 5V but would be capped at 3.3V (VDD). 2) is to use an external 3.3V reference, with gain = 1 setting. Gain = 2 can also be used but still caps the output voltage to VDD. 
 
 dougcl said: Can this device be used with an external reference? dougcl said: Can the internal reference be disabled on this device so that VREF (pin 21) can be used as an input for an external reference? 
 Yes, you can disable the internal reference by writing to the register with command 0111 and DB0=1. 
 
 Best regards, 
 Ian)

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What is the AD5673R Channel Output Voltage?