Why is PAC1921 not responding to gain settings changes?
In the GUI "PAC1921 High Side Current Sense and Power Monitor (ADM00592) GUI Software", having 'Enable Auto INT_EN' inactive keeps the PAC1921 device in the READ state (low power mode). Activating this push button solves the issue. As stated in section "4.2.2.1 ENABLE AUTO INT_EN" of the "PAC1921 High-Side Current/Power Sensor Evaluation Board User’s Guide":
"It is recommended that the “Enable Auto INT_EN” control be activated when using the GUI."
Read the entire section for more information. Also, see section "4.4 Power States" of the user's guide, which is available on the PAC1921 product page.