ISL12024 Intersil Corporation, ISL12024 Datasheet - Page 14

• Manufacturer Part Number: ISL12024
• Description: Real-Time Clock/Calendar
• Manufacturer: Intersil Corporation

normal power. The three-second delay is intended to lock
out any power-up glitches that could cause communications
errors. Also note that very fast (<10us) power ramp rates will
bypass this delay so it is important to filter V
OPTION 1- STANDARD (POWER CONTROL) MODE
In the Standard Mode, the supply will switch over to the
battery when V DD drops below V
lower. In this mode, accidental operation from the battery is
prevented since the battery backup input will only be used
when the V DD supply is shut off.
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
• Battery Backup Mode (V
There are two discrete situations that are possible when
using Standard Mode: V BAT < V TRIP and V BAT >V TRIP .
These two power control situations are illustrated in Figures
9 and 10.
(V
To transition from the V
following conditions must be met:
- Condition 1:
- Condition 2:
The ISL12024ISL12024 device will switch from the V
to V
- Condition 1:
- Condition 2:
FIGURE 9. BATTERY SWITCHOVER WHEN V
V
BAT
V
where V
V
where V
V
where V
V
where V
V
V
TRIP
BAT
DD
DD
DD
DD
DD
DD
V
BAT
)
< V
< V
> V
> V
mode when one of the following conditions occurs:
- V
BATHYS
TRIP
BATHYS
TRIPHYS
BAT
TRIP
BAT
TRIP
BATHYS
- V
+ V
≈ 2.2V
+ V
BATHYS
BATHYS
≈ 50mV
≈ 50mV
TRIPHYS
≈ 30mV
BATTERY BACKUP
DD
BAT
14
to V
DD
MODE
) to Normal Mode (V
) to Battery Backup Mode
TRIP
BAT
mode, both of the
or V
BAT
V
DD
BAT
, whichever is
BAT
well.
+ V
< V
DD
BATHYS
2.2V
1.8V
TRIP
)
BAT
ISL12024
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. Care should be taken when
changing from Normal to Legacy Mode. If the V
higher than V
and unless the battery is disconnected or the voltage
decreases, the device will no longer operate from V
To select Option 2, the BSW bit in the Power Register must
be set to “BSW = 1”.
• Normal Mode (V
• Battery Backup Mode (V
The Legacy Mode power control conditions are illustrated in
Figure 11.
Serial Communication
The device supports the I
Clock and Data
Data states on the SDA line can change only during SCL
LOW. SDA state changes during SCL HIGH are reserved for
indicating start and stop conditions (see Figure 12).
V
To transition from the V
conditions must be met:
V
The device will switch from the V
the following condition occurs:
V
FIGURE 10. BATTERY SWITCHOVER WHEN V
BAT
FIGURE 11. BATTERY SWITCHOVER IN LEGACY MODE
DD
DD
V
V
V
TRIP
DD
BAT
< V
> V
BAT
BAT
V
DD
TRIP
- V
+V
OFF
, then the device will enter battery back up
BATHYS
BATHYS
DD
) to Battery Backup Mode (V
V
BATTERY BACKUP
DD
2
DD
C protocol.
BAT
MODE
to V
DD
) to Normal Mode (V
to V
BAT
BAT
VOLTAGE
BAT
mode, the following
to V
is simply done by
V
TRIP
DD
BAT
BAT
+ V
mode when
ON
October 18, 2006
TRIPHYS
BAT
DD
voltage is
> V
DD
3.0V
2.2V
.
FN6370.1
TRIP
)
)
In