I am using an ADM1260 in a new design. I am using VX1 thru VX4 as digital inputs from various power good circuits. They are each externally pulled up to VDDCAP thru 100k resistors. Various sources should pull down on them if "power is not good".
For now I've removed any sequencing and am just enabling everything.
I can measure these VX1-VX4 nets on the board right at the pull-up resistors, and they are at VDDCAP (around 4.8V) on both sides of the pullup resistors. However, the ADM1260 sees them as LOW instead of HIGH...
If I turn on the A/D converter for those inputs, it reads out 2.048V (i.e. it is maxed out) which I think makes sense given the inputs are at 4.8V. So I am confident these are getting all the way to the chip (i.e. not bad solder joints or something).
With the A/D off I have them configured in "GPI Fault" mode, no glitch filter, Invert disabled, Level Detect, Pull down disabled. I can not understand why they are showing up as LOW instead of HIGH. I checked the data sheet and the logic threshold should be 2V or less, which I am well above...
I know my connection to the chip thru ADI Power Studio 1.5.4.0 is good because I can program the chip, and I can see the VH and VP1 voltages being read, etc.
These power good signals working were part of my plan for sequencing things, so having them stuck low (i.e. bad state) is tipping my apple cart.
Edit Notes
just added a bit of detail.[edited by: matt.nickels at 9:27 PM (GMT -4) on 8 May 2024]
