AD9717: Pin connection

Q

Please advice me how to connect "DVDD" pin, 1. to a capacitor only 2. to 3.3V
3. do i need to activate the internal LDO or not. 4. others I'm confused since
on top of Table 1 it's define "DVDD=3.3V" in "absotute max" table DVDD is 2.1V
max and all inputs are 0.3V max above.

A

Table 1 defines DVDD =1,8V (not 3.3V). Table 1 defines DVDDIO =3.3V. The
absolute max ratings for DVDD = -0.3V to +2.1V, DVDDIO = -0/3V to 3.9V
(You might be looking at an older datasheet as Rev0 to RevA changes included
changing DVDD=3.3V to DVDD =1.8V for table 1. This is noted in the revision
history for REVA datasheet which is available at www.analog.com )

A 1.0 μF bypass capacitor at DVDD (Pin 7) is required when using the LDO. Since
DVDDIO >1.8V (in your case) then, bypass DVDD with a 1.0 μF capacitor; however,
do not otherwise connect it. (see evaluation board schematic at end of the
datasheet).

“As stated in the datasheet: LDO is provided for DVDDIO supplies greater than
1.8 V, or the 1.8 V can be supplied directly through DVDD. A 1.0 μF bypass
capacitor at DVDD (Pin 7) is required when using the LDO”.

See also DVDD pin description on page 10

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