ISL12026 Intersil Corporation, ISL12026 Datasheet - Page 13

• Manufacturer Part Number: ISL12026
• Manufacturer: Intersil Corporation

Power Control Operation
The power control circuit accepts a V
Many types of batteries can be used with Intersil RTC
products. For example, 3.0V or 3.6V Lithium batteries are
appropriate, and battery sizes are available that can power
an Intersil RTC device for up to 10 years. Another option is
to use a SuperCap for applications where V
for up to a month. See the Applications Section for more
information.
There are two options for setting the change-over conditions
from V
register controls this operation.
Note that the I
battery backup, that function is controlled by the SBIB bit.
That operation is covered after the power control section.
OPTION 1- STANDARD POWER CONTROL MODE
In the Standard mode, the supply will switch over to the
battery when V
lower. In this mode, accidental operation from the battery is
prevented since the battery backup input will only be used
when the V
To select Option 1, BSW bit in the Power Register must be
set to “BSW = 0”. A description of power switchover follows
Standard Mode Power Switchover
• Normal Operating Mode (V
To transition from the V
following conditions must be met:
• Battery Backup Mode (V
- Option 1 - Standard Mode
- Option 2 - Legacy Mode (Default)
(V
- Condition 1:
- Condition 2:
and AL1E bits are set to 1, then only the AL0E PIM alarm
will function (AL0E overrides AL1E). The IRQ/F
output will now be pulsed each time an alarm occurs. This
means that once the interrupt mode alarm is set, it will
continue to alarm for each occurring match of the alarm
and present time. This mode is convenient for hourly or
daily hardware interrupts in microcontroller applications
such as security cameras or utility meter reading.
Interrupt Mode CANNOT be used for general periodic
alarms, however, since a specific time period cannot be
programmed for interrupt, only matches to a specific time
of day. The interrupt mode is only stopped by disabling
the IM bit or the Alarm Enable bits.
BAT
V
where V
V
where V
DD
DD
DD
)
< V
< V
to Battery back-up mode. The BSW bit in the PWR
DD
BATHYS
TRIP
BAT
TRIP
2
DD
supply is shut off.
C bus may or may not be operational during
- V
≈ 2.2V
drops below V
BATHYS
≈ 50mV
DD
to V
BAT
13
DD
) to Normal Mode (V
BAT
) to Battery Backup Mode
TRIP
mode, both of the
DD
or V
and a V
BAT
DD
, whichever is
is interrupted
BAT
DD
OUT
input.
)
ISL12026
The ISL12026ISL12026 device will switch from the V
V
There are two discrete situations that are possible when
using Standard Mode: V
These two power control situations are illustrated in Figures
9 and 10.
OPTION 2 -LEGACY POWER CONTROL MODE
(DEFAULT)
The Legacy Mode follows conditions set in X1226 products.
In this mode, switching from V
comparing the voltages and the device operates from
whichever is the higher voltage.
To select the Option 2, BSW bit in the Power Register must
be set to “BSW = 1”
• Normal Mode (V
To transition from the V
conditions must be met:
V
• Battery Backup Mode (V
DD
DD
- Condition 1:
- Condition 2:
FIGURE 10. BATTERY SWITCHOVER WHEN V
FIGURE 9. BATTERY SWITCHOVER WHEN V
V
V
V
V
V
where V
V
where V
V
mode when one of the following conditions occurs:
V
TRIP
< V
TRIP
BAT
DD
BAT
DD
DD
DD
V
BAT
BAT
> V
> V
- V
- V
BATHYS
TRIPHYS
BAT
TRIP
V
BATHYS
TRIP
BATHYS
+ V
+ V
DD
BATHYS
≈ 50mV
TRIPHYS
) to Battery Backup Mode (V
≈ 30mV
BATTERY BACKUP
DD
BAT
BATTERY BACKUP
to V
BAT
< V
MODE
MODE
DD
) to Normal Mode (V
BAT
TRIP
to V
mode, the following
BAT
and V
is simply done by
V
TRIP
BAT
V
BAT
BAT
+ V
BAT
>V
+ V
TRIPHYS
BAT
< V
TRIP
> V
DD
April 13, 2006
BATHYS
3.0V
2.2V
BAT
2.2V
1.8V
TRIP
)
)
FN8231.3
TRIP
.
to