My custom board with iMX6UL just arrived and it is not detected by PC (via USB). I checked boot switches, voltage levels, etc. After some more investigation, I think power-up sequence might be the problem.
I use PF3001 with A7 option in my design. VDD_HIGH_IN is connected to SW2 output and VDD_SOC_IN is connected to SW1 output. I realized that datasheet says VDD_HIGH_IN must be powered before VDD_SOC_IN. However, in PF3001 A7 configuration, SW1 and SW2 have the same sequence number, which is 3.
If really that is the problem, what I want to do is to change start-up sequence so that SW2 is ready before SW1 is turned on. I realize that V33 output could have beed used for VDD_HIGH_IN. But right now, that is not an option.
PF100 has this TBB (try before buy) feature to allow changing start-up sequence. PF3001 datasheet does not mention it, but is there any way to change start-up sequence of PF3001?