Hi All,

I have a battery powered, embedded application for a Teensy 3.2.

I want to use the RTC for wakeup from hibernate. I don't really have space for an extra battery. My project is already battery powered - I have a single 16850 battery that supplies power to Vin. It is max just over 4v and a battery charger charges the project when it's actively in use.

My question: can I also connect my 16850 battery to the VBat for the RTC? Could I use a resistor for voltage drop?

The datasheet for the processor suggests the range for VBat 1.71 to 3.6v. And the current draw is in the 1 - 2uA range. By my calculations, that suggests I need to drop (let's say 1v) at 2uA.

So a 600K resistor seems a good choice to drop 3.3v-4v down to an appropriate range for VBat? I could use a voltage divider - but is that really necessary in this case?

And yes, I know I need a crystal - I have just ordered one.