Hi,
I'm working on a board that uses an npm1100 (QFN) in the following configuration:
When testing my board, I populated it with only the components shown in the above schematic and supplied 5V to VBUS (no battery attached). For some reason, VSYS reads only 0.5V and VCC (the output of BUCK) reads 4.9 - almost the same as the input voltage. My power supply also indicates that the npm1100 is drawing ~5mA in this configuration (with no load), far above its rating.
Is something wrong with my schematic? I can't find any behavior in the datasheet that would explain any of this behavior. I suspected it might be a short, but manual probing of the board shows that everything is connected as the schematic indicates, and no part of the board is getting hot. I did have a mistake in the original board layout, but I've confirmed that my cut traces and bodge wires match the above schematic.
(As an aside - does the QFN24 center pad need to be connected to ground, or can it be left floating? The datasheet doesn't specify, but some of the example schematics show a "pin 25" listed as a second AVSS and connected to ground)
