S08SHX v S08PAX current draw at 3.3V / 3V

[carlnormansuret]

Hi Guys,

I have a design that runs off a single CR2032 3V battery. I ported the SH4 code to PA4 which was quite a big task due to the amount of features we use. Anyway, the problem now is that in the data sheet, and in testing, the current draw at 3.3V the PA4 draws ~4uA in stop mode, and the SH4 draws 1uA. Down below 3.1V they are "the same" measuring around 1uA.

Is there a way and/or reason that the PA4 is so terrible between 3.1V to 3.3V? But fine from 3.1V down to 2.8V? I would have thought this newer PA4 processor would run at 3.3V because of lion batteries. It takes a significant chunk of life out of the design going from 1uA to 4uA for the first portion of its life. Obviously once the CR2032 has been powered on it will drop under 3.1V, but its not ideal.

[miduo]

Actually it is hard to say why the PA4 is worked as this. Although the PA4 and SH4 is pin-compatible, however internal peripheral is different for the two parts. So the behaviour as you mentioned is quite normal. I will consult the S08 expert to get more information regarding this issue, and let you know.

[carlnormansuret]

Hi Fang, did you get any more information about the 4uA current draw at 3.3V and 1uA currnet draw at 3V?