Does anyone have more detail on the Photon / P1 power requirements? The Photon has a 600ma step-down converter, and the Photon spec has 235-400ma peak current requirements. What does this mean for sizing a step-up converter? Is it possible to source these peak current requirements from a capacitor? (what is the duration of these peaks?)
How does the Photon requirements differ from the P1 requirements?
Any suggestions for step-up converters for the P1 / Photon would be appreciated.
Yes these can be sourced from capacitors pretty easily. These currently are listed in the USI datasheet, so they are perpetuated here. That said, I haven’t seen these currents on the VIN pin when supplying the Photon with 5V. The current has been 80-100mA on average. Average current on the 3V3 pin between the output of the SMPS and input of the PØ/P1 will be higher, roughly 150mA @ 3.3V.
What do you think a reasonable 3.3V current figure / capacitor combination would be? Does a 300ma boost converter with something like 22uF on the output work?
Honestly at this point in time I would recommend a 600mA convertor with 22uF caps just like we have on the Photon. Anything less has not been tested yet, and any I/O sourcing will subtract from the available overhead which is already quite small with the 600mA convertor. If you test something with less capability and it’s working great, please let us know!
Any update on these min P1 power specs lately? 600mA+ seems crazy high for a wifi module that's averaging 80-100mA. I understand the need to deal with the peak currents, but has anyone found what the actual minimum current is to do that (with caps), without seeing brownouts, etc? When I see the phrase:
in the datasheet, it makes me wonder about the tested accuracy of such specs. I'm attempting to design a completely minimalist power circuit to drive this guy and every mA counts. And of course I can't be worrying about brownouts. Thanks!