this regulator uses only 1.6 uA when it's disabled. To enable to regulator, the EnablePin must to driven high.
The DS3234 can sleep, using only 1.5uA from it's coin cell battery. So I want to shut down my project (Atmega328 is the base of it), by controlling the MAX16910 regulator with the INT pin from the DS3234. But the DS3234 uses it's alarm to trigger the INT Pin to go LOW, but the MAX16910's enable pin is active high, so to startup the regulator, i have to pull its enable pin HIGH. Is it possible to have the DS3234's INT pin do this with minimal extra components and quiescent current?
INT is an open drain so you need a pullup resistor there. ENABLE has pulldown current of 0.65uA. So it seems you have to use a pullup resistor wired from INT to IN. Connect INT to ENABLE. The pullup resistor value would be something like V(IN)/1.5uA then..
It depends on the logic of your switching ENABLE on/off, however. When the regulator shall be switched off when INT is high you need an inverter there (ie. an n-channel mosfet and an additional resistor).
I think the BSS138W is what I need, but I'm not sure of the schematic. Here's a photo of an attempt.
The MAX16910 when powered up, will supply 5V to the DS3234, an Atmega chip, and other components like a LCD, etc. When it's not powered up, the DS3234 will run on low quiescent current from it's coin cell battery, awaiting the next alarm trigger to power things back up.
I really would like to be able to power up a project using the alarm from the DS3234 RTC, so as to have ultra low quiescent current. The DS3234 only uses about 1.5uA when running off the coin cell, and the MAX16910 regulator only uses 1.6uA when in shutdown. I see 2 problems I'm not sure how to overcome.
The data sheet says the INT pin on the DS3234 needs a pull-up resister. But if it's connected to 5V like in my schematic, there isn't 5V because the regulator will be powered off.
Enable on the regulator needs to be pulled high (2.4V or more, from the data sheet) to start up the regulator. But when the RTC chip's alarm is triggered, the INT pin goes LOW.
I've drawn up these 2 components with their recommended schematics from the data sheets. See the attached photo or pdf file.
thanks for the help!
