STM804 STMICROELECTRONICS [STMicroelectronics], STM804 Datasheet - Page 12

• Manufacturer Part Number: STM804
• Description: 3V Supervisor with Battery Switchover
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

STM690/704/795/802/804/805/806
Using a SuperCap™ as a Backup Power
Source
SuperCaps™ are capacitors with extremely high
capacitance values (e.g., order of 0.47F) for their
size. Figure
a back-up power source. The SuperCap may be
connected through a diode to the V
Since V
the reset threshold, there are no special precau-
tions when using these supervisors with a Super-
Cap.
Figure 15. Using a SuperCap™
12/31
5V
BAT
can exceed V
15
V
V
CC
BAT
STMXXX
shows how to use a SuperCap as
GND
V
RST
OUT
CC
To external SRAM
To µP
while V
AI08805
CC
CC
is above
supply.
Negative-Going V
The STM690/704/795/802/804/805/806 Supervi-
sors are relatively immune to negative-going V
transients (glitches).
erated using a negative pulse applied to V
starting at V
threshold by the magnitude indicated (comparator
overdrive). The graph indicates the maximum
pulse width a negative V
without causing a reset pulse. As the magnitude of
the transient increases (further below the thresh-
old), the maximum allowable pulse width decreas-
es. Any combination of duration and overdrive
which lies under the curve will NOT generate a re-
set signal. Typically, a V
100mV below the reset threshold and lasts 40µs or
less will not cause a reset pulse. A 0.1µF bypass
capacitor mounted as close as possible to the V
pin provides additional transient immunity.
RST
+ 0.3V and ending below the reset
CC
Figure 32., page 20
Transients
CC
CC
transient that goes
transient can have
was gen-
CC
CC
CC
,