Andy Green wrote: > Again I tested bringing external 3V3 to IO_3V3 and it causes the device > to start OK without battery.
Hmm, not here :-( io_3v3.png shows VB_SYS (yellow) and IO_3V3 (blue), VB_SYS bypassed to GND with 10uF, nothing else happening. io_3v3-zoom.png shows the same scenario, but zoomed into the event. Then I added an external 3.3V through a 1 Ohm resistor. io_3v3-powered.png shows what IO_3V3 looks like. To check that I really got IO_3V3, I added the usual external 100uF bypass to VB_SYS, removed the power injection, and let the system boot my 0.5 Hz LED blinker. This is shown in io_3v3-normal.png I tried varying the resistor, but that only allowed me to vary between io_3v3.png and io_3v3-powered.png, but didn't help: R IO_3V3 (Ohm) min(V) max(V) 1 3.00 3.60 47 2.00 3.12 100 1.20 2.52 150 0.72 2.08 open -0.08 1.48 With the 1 Ohm resistor, the PMU powers off after a minute or so. Guess it doesn't like to share ;-) So it seems that stabilizing IO_3V3 alone does not solve the issue. - Werner
<<attachment: io_3v3.png>>
<<attachment: io_3v3-zoom.png>>
<<attachment: io_3v3-powered.png>>
<<attachment: io_3v3-normal.png>>
