I'm facing a little mystery (or simply confusion) in using the ADP5063. I've got a circuit that amounts to little more than an ADP5063 breakout, while having the chip's output (ISO SX pins) feeding a 3.3V buck/boost. The ADP5063 portion is setup as attached.
My problem: when I apply 5V to the input (cold start, without having a battery attached), the output from the ISOSX pins is loooow: ~1.7V.
After a bit of experimenting, I've found that it will sit at this level until I bring DIG_IO1 high (I need only momentarily connect the pin to the 1.7V output, in fact) at which point the level will shoot up to ~4.3V and stay there.
This is the behaviour that I want by default--output 4V when I have external power. My questions:
- is this expected/normal behaviour?
- is there a way to set things up (ideally, through the I2C interface once and for all) so that it will start up this way by default, without interaction on the DIG_IOX pins side?
- from what I gather, the function of the DIG_IOX pins is factory-programmable--but I'm still unclear on what their default setting/function is--can you point me to the spot in the datasheet where this is described?