I am wanting to run battery based system with an attiny3216 as the controller.
I got a simple 5v 18650 charger/boost module based on an IP5306 Injoinic (china) chip that normally supplies 5 volts. These seem great are really small "intelligent??" units with a sleep mode.
These units work fine when there a reasonable load however it drops to 2.9 when there is no load detected.
I thought great the tiny in sleep mode will happily run at that but then I found another problem.
In the in and out of sleep mode the power is cut and the tiny is killed.
( I think that it is to avoid inrush current issues.)
Anyway the end result is the tiny is killed which is not what I want.
My real question here is can I just hook the tiny to the battery directly. so it is powered whilst the IP5306 is charging/sleeping/powering the other higher use stuff.
Will there be any risk to the tiny being directly connected to the battery.
Could You make a wiring diagram and attach it? Those poetry diagrams always leave some things out.
You tell about problems when there is "no load". How much load is needed? Could a resistor work? What value then....
As long as the load is small relative to the battery charging current, you can generally get away with that (if it's not, it can confuse the charger, and I'm not sure how various charging IC's will react to it). I do that in the designs I run from rechargable LiPo batteries, and haven't had issues (the designs are the typical sort of "sleep most of the time" designs, with charging current on the scale of hundreds of mA and load ~20mA active, but almost always sleeping with very low current).
The tiny has no problem with it (though, make sure it's a protected cell, so if (when) you accidentally short power on your prototype, the battery pack won't catch fire - I'd probably throw a PTC fuse in line with it (well, actually I'd use one of my '3216 boards, which have that - running off a battery like that would call for the "no regulator" option)