I tried the NXP SDK example of 'lpcxpresso55s69_power_manager_lpc'.
This nicely demonstrates most of the low power modes of LPC55s69, but I have a problem with the NXP library function: POWER_EnterDeepPowerDown()
On the example this function fails to set deep-power-down state and MPU current is same as running current. I suspect it's ending up in hard fault handler, but it's really difficult to debug because it's in library code AND because changing clocks etc prior to entering deep-power-down stops the debugger from being attached to the target.
Would it be possible to get a copy of source code for this function so I can get a better idea of what is going wrong.