1. Questions
Andrew Baek
October 16, 2017

2. Strategy
The button is connected to a pin that is pulled up in off state
We would like to minimize any current flow into the MCU
So the idea is to use 74LVC1T45FW4-7 as an “isolator”
The question is whether 74LVC1T45FW4-7 needs to be powered on to keep nQON high when the system is off

3. 74LVC1T45FW Off-State
This is connected nQON on BQ25895, and pulled up in an off-state
What happens if VCCB is off. Would the B pin be either low or Hi-Z (tri-stated)?
If tri-stated, I can turn off VCCB in off state
This will be off
This is connected to a GPIO on MCU
Connected to VBAT so 74LVC1T45FW4-7 does not load down the nQON in off state.

4. 74LVC1T45FW On-State
nQON will go low (active low) when a user pushes the button
We would like to VCCB to be 2.8V. The voltage level on nQON can be 3.5V to 4.2V (need to check with BQ25895 review team)
This will be 2.8V, VDD of MCU
When “On”, any active low will trigger some actions on the MCU