At this core board current consumption abnormal high issue,
When we apply DC3.3V to core, the current consumption is 350mA, whereas the former MaChao whole system current consumption is just 160mA. We are in facking PANIC!!
Try to decrease by-pass capacitor; lower the floating I/O pin current consumption; PCB layout issue; ferrite beads internal resistance too high; resistors of the voltage ladder provide Vref of DDR too low; and many other facking guess...all in FACKING VAIN!!
Finally, we find someone who knows power well(he is a facking good power chip designer!!). He told us not just see the current consumption, we should consider the POWER CONSUMPTION!!
Do some simple calculation, the former Machao system is DC12V supply and 160mA current consumption, thus the power consumption is 12*0.16=1.92(W). Then for core board is DC3.3V supply and 350 current consumption, thus the power consumption is 3.3*0.35=1.155(W). Well, the power consumption seems a facking reasonable way.
Then I do a experiment, build a voltage regulate board which is DC12V to DC3.3V, the core board apply the DC3.3V from the regulation board. Then we can see the current consumption is low to 100mA by DC12V source. Perfect!!
During this issue, we learned about not only the current consumption, the power consumption is needed to be considered. The P=VI equation is really FACKING IMPORTANT!!
