Other Parts Discussed in Thread: INA190,
I have a UCD90320U which is set up with multiple MON pins as current monitors. I am using the INA190A5 current sense amplifier and a variety of shunt resistor sizes. There are no additional resistor dividers between the INA190 and the sequencer.
When I poll the currents for these rails, the sequencer returns current readings in 15.625mA steps. This is regardless of what Iout Cal Gain is used (if I use a different Iout Cal Gain value, the current is scaled accordingly, but the returned readings are still in 15.625mA steps). 15.625mA is pretty poor resolution for a current monitor, if I have a rail that is only meant to draw a few 10s of mA, this makes it difficult to set proper warn/fault limits. Additionally, the sequencer returns up to 31.25mA readings for rails that are completely off, and should read near zero currents.
I am confident that the analog voltage out of the INA190 corresponds properly to currents that are non-15.626mA multiples, and is at a near 0 voltage when currents are zero. Is there a firmware setting that I am missing in the UCD90320U configuration? Or is this a limitation of the chip itself