Mosaic
Well-Known Member
Hi,
I'm looking at having a 16F886 go into a power loss code loop if AC power is lost. It can detect AC lost via loss of a 12V supply line.
I'm thinking about placing a Li Ion batt (4.2V max, 3.7V typical) inline with a switching diode so the 5.12v Vcc of the µC keeps it rev biased during normal ops. That should supply the µC (2.5v to 5.5v) with over 3V during power loss.
The two challenges:
1) Recharging the Li ion simply: perhaps via a couple diode drops and a current limiting resistor from the 5.12V supply?
2) Figuring out the difference between AC power loss and a genuine power down via the A.C. SPST switch.
Item 2 is making me think along the lines of a DPDT AC switch with one pole dedicated to the switching the Li Ion into the circuit so when the switch is off, so is the battery backup.
Any advice on this?
Edit Perhaps this Switch:
**broken link removed**
I'm looking at having a 16F886 go into a power loss code loop if AC power is lost. It can detect AC lost via loss of a 12V supply line.
I'm thinking about placing a Li Ion batt (4.2V max, 3.7V typical) inline with a switching diode so the 5.12v Vcc of the µC keeps it rev biased during normal ops. That should supply the µC (2.5v to 5.5v) with over 3V during power loss.
The two challenges:
1) Recharging the Li ion simply: perhaps via a couple diode drops and a current limiting resistor from the 5.12V supply?
2) Figuring out the difference between AC power loss and a genuine power down via the A.C. SPST switch.
Item 2 is making me think along the lines of a DPDT AC switch with one pole dedicated to the switching the Li Ion into the circuit so when the switch is off, so is the battery backup.
Any advice on this?
Edit Perhaps this Switch:
**broken link removed**
Last edited: