UPS25 26
RTD Embedded Technologies, Inc
Voltage monitors
There are two independent voltage monitors on the UPS25. One continuously
monitors for the presence/level of the main supply VIN. If the main supply drops
under 10V the UPS25 stops charging and enters backup mode. In case the
interrupt output of the control logic is enabled an IRQ is asserted to the host
indicating low or failing power. This bit can also be interrogated from the charger
status register bit #0
The other voltage monitor follows the battery voltage BATT and is indicated by bit
#1 of the charger status register. This bit remains “high” while the battery backup
to the power supply remains over 8V. This status bit can be used to indicate a
“soon empty” battery.
The levels of the trip-points of these voltage monitors can be adjusted using the
onboard trim pots. See figure 4-3 below:
Fig. 4-4 Trip point adjustment trim pots for VIN and BATT levels
