Hi! I am facing a weird situation with regard to powering the EVAL-AD5780 board. As per the user guide UG-256 (RevA),
I need to supply 5 V between the VCC and DGND inputs for the digital supply and 7.5 V to 16.5 V between the VDD and AGND inputs and −2.5 V to −16.5 V between the VSS and AGND inputs for the negative analog supply of the AD5780.
I was supplying +5V for digital and +-15V for the analog and I was completely unable to make the board work. My Links are positioned as follows LK1 - B (external power supply), LK2 - A (+5v), LK3-A (unity gain), LK4,LK5,LK6, removed , LK7 inserted ,LK8 B (AGND) and LK9, LK11 Inserted. As per the instructions, I was always powering on the digital supply before connecting the analog supply. It was not working at all. I was getting +5 at Vref but v_buff_out was flat-out zero regardless of what I sent over SPI.
However, at one point I accidentally connected the analog supply without the digital one and it started working normally. Now, Basically, Nothing is connected between VCC and DGND. VDD and VSS are connected to =-15 V respectively. And It is working.
My question is, What I was doing wrong, or are the instructions on the user guide wrong?
