Datasheet

STM690A/692A/703/704/802/805/817/818/819 Operation
Doc ID 10522 Rev 10 17/43
Figure 13. Power-fail comparator waveform (STM817/818/819)
Figure 14. Power-fail comparator waveform (STM690A/692A/703/704/802/805)
2.10 Using a SuperCap™ as a backup power source
SuperCaps™ are capacitors with extremely high capacitance values (e.g., 0.47 F) for their
size. Figure 15 shows how to use a SuperCap as a backup power source. The SuperCap
may be connected through a diode to the 5 V supply. Since V
BAT
can exceed V
CC
while V
CC
is above the reset threshold, there are no special precautions for using these supervisors
with a SuperCap.
AI08804a
V
CC
V
RST
V
SO
(or 2.4V)
t
rec
RST to E
CON
Delay (STM818)
RST
E
CON
(STM818)
PFO
(STM817/819)
PFO follows PFI PFO follows PFI
AI08832a
V
CC
V
RST
2.4V (or V
SO
)
t
rec
RST
PFO
PFO follows PFI PFO follows PFI