So I'm trying to design a small embedded IoT device with some very dynamic power routing. Hopefully the following will explain what I'm attempting to do.
The device needs to be able to take both a rechargeable li-ion battery OR a non-rechargeable lithium battery of the same form factor. These two batteries will both be CR2450 format.
The TWO device charge and power inputs will be 5v USB as well as a wide voltage input pin (around 4 to 20 VDC). I plan to have these two sources placed in parallel via two diodes feeding the input pin (VBUS) of a BQ24210. The BQ24210 BAT pin will connect to both the positive side of the CR2450 battery holder as well as the input to a buck-boost converter which will generate 3.3V for my micro-controller.
Now, how will the BQ24210 behave if I do not place any battery in the battery holder and the BQ24210 BAT pin is connected directly to the input of my buck-boost? Asked differently: will the BQ24210 act as a voltage regulator for my buck-boost if I apply 15 or 20 volts to the BQ24210 VBUS pin? Note: I have not designed the buck-boost yet and it's draw will vary greatly depending on the state of my larger embedded system.
I ask because I want to have an option on my PCB to add a small diode at the positive pin of the CR2450 battery holder so that I can use a non-rechargeable battery and keep the BQ24210 from trying to charge it, but I want to retain the external wide input voltage capability.
Thanks!
