ISL12029 Intersil Corporation, ISL12029 Datasheet - Page 15

• Manufacturer Part Number: ISL12029
• Description: Real Time Clock/Calendar
• Manufacturer: Intersil Corporation

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AL0 for Alarm 0), indicate if an alarm has happened. The bits
are set on an alarm condition regardless of whether the IRQ/
F
register are reset by the falling edge of the eighth clock of
status register read.
There are two alarm operation modes: Single Event and
periodic Interrupt Mode:
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.
- Option 1 - Standard Mode
- Option 2 - Legacy Mode (Default)
Note that the I
battery backup, that function is controlled by the SBIB bit.
That operation is covered after the power control section.
1. Single Event Mode is enabled by setting the AL0E or
2. Interrupt Mode (or “Pulsed Interrupt Mode” or PIM) is
OUT
AL1E bit to “1”, the IM bit to “0”, and disabling the
frequency output. This mode permits a one-time match
between the alarm registers and the RTC registers. Once
this match occurs, the AL0 or AL1 bit is set to “1” and the
IRQ/F
until the AL0 or AL1 bit is read, which will automatically
resets it. Both Alarm registers can be set at the same time
to trigger alarms. TheIRQ/F
either alarm, and will need to be cleared to enable
triggering by a subsequent alarm. Polling the SR will
reveal which alarm has been set.
enabled by setting the AL0E or AL1E bit to “1” the IM bit
to “1”, and disabling the frequency output. If both AL0E
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.
interrupt is enabled. The AL1 and AL0 bits in the status
DD
OUT
to Battery back-up mode. The BSW bit in the PWR
2
output will be pulled low and will remain low
C bus may or may not be operational during
15
OUT
output will be set by
DD
and a V
DD
is interrupted
BAT
OUT
input.
ISL12029
OPTION 1- STANDARD POWER CONTROL MODE
In the Standard mode, the supply will switch over to the
battery when
lower. In this mode, accidental operation from the battery is
prevented since the battery backup input will only be used
when the
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:
- Condition 1:
- Condition 2:
• Battery Backup Mode (V
The ISL12029 device will switch from the V
when one of the following conditions occurs:
- Condition 1:
- Condition 2:
There are two discrete situations that are possible when
using Standard Mode:
These two power control situations are illustrated in Figures
13 and 14.
(V
V
where V
V
where V
V
where V
V
where V
FIGURE 13. BATTERY SWITCHOVER WHEN V
DD
DD
DD
DD
V
BAT
V
V
TRIP
BAT
DD
V
< V
< V
> V
> V
BAT
)
V
BATHYS
TRIP
BATHYS
TRIPHYS
BAT
TRIP
BAT
TRIP
DD
- V
V
BATHYS
- V
+ V
DD
supply is shut off.
≈ 2.2V
+ V
BATHYS
BATHYS
drops below VTRIP or VBAT, whichever is
≈ 50mV
≈ 50mV
TRIPHYS
≈ 30mV
V
DD
BATTERY BACKUP
BAT
to V
BAT
<
DD
MODE
) to Normal Mode (V
V
BAT
) to Battery Backup Mode
TRIP
mode, both of the
and
V
BAT
BAT
V
BAT
BAT
to V
+ V
>
V
DD
< V
April 17, 2006
DD
BATHYS
TRIP
2.2V
1.8V
)
FN6206.4
TRIP
mode
.