We've got a design using an LPC54114 which we noticed had unexpectedly high deep power-down current of 80 uA, just with the processor and an analog reference voltage attached (2.5V ref, which consumes max 1.5 uA).
Some steps I've followed to debug the issue so far are:
I followed the instructions in the errata re: the ADC excess power consumption and observed no effect whether I left the pins as analog or digital when entering deep power-down.
We were powering VDDA and VREFP from the same 7mA 2.5V reference; when I powered VDDA directly from the same source as VCC at 3.6V (vrefp still 2.5V) the power consumption dropped to 20 uA (from 80).
Following those steps I then tried dropping the input voltage (VCC/VDDA) and observed:
20 uA @ 3.6V
8 uA @ 3.3V
3.5 uA @ 3.0V
2 uA @ 2.5V (vref removed)
Am I configuring something incorrectly or is this expected behaviour? The data sheet only lists 1.62V and 2.0V tests (at 290 nA and 330 nA respectively). This is significantly higher power consumption than the LPC11U68 we replaced, so it's unexpected.