Other Parts Discussed in Thread: REF35
Hi,
I'm implementing an application that requires running the MCU only on battery power in the event of a power outage (expected consumption around 25uA). The request is to use a very small battery and therefore I would like to be able to eliminate the consumption of the REF30/REF33 to reduce battery consumption.
To do this I thought of powering the REF with the normal power supply and using two diodes to lower the 5V_MCU backup voltage below the reference value (in the example case 4.096V).
Unfortunately I cannot power the VREF at 0V, the reason lies in the fact that the MCU must have VDDA equal to VCC (at least 100mV) and have VREFH not lower than 2.5V (in the example case). Driving VREF to 0V can damage the MCU.
When the MCU is in ultra sleep mode I don't need to make analog measurements. Of course I don't want to put a diode in series with the REF which would make it useless to have poor voltage reference accuracy.
Having said all that, can the REF work in OR with the diodes? Would there still be a quiescent current?
Below is a block diagram to give you an idea of the implementation:
Thank you
Marco
