ISL12026 Intersil Corporation, ISL12026 Datasheet - Page 22

• Manufacturer Part Number: ISL12026
• Manufacturer: Intersil Corporation

Once the registers are set, the following waveform will be
seen at IRQ/F
Note that the status register AL0 bit will be set each time the
alarm is triggered, but does not need to be read or cleared.
I
Operation in Battery Backup mode is affected by the BSW
and SBIB bits as described earlier. These bits allow flexible
operation of the serial bus and EEPROM in battery backup
mode, but certain operational details need to be clear before
utilizing the different modes. Table 8 describes 4 different
modes possible with using the BSW and SBIB bits, and how
they are affect the serial interface and battery backup
operation.
• Mode A - In this mode selection bits indicate a Standard
2
C Communications During Battery backup
B (X1226
Mode switchover combined with I
backup mode. When the V
lower of V
backup mode. If the microcontroller and bus pullups are
MODE
Mode)
C
D
A
RTC and alarm registers are both “30” sec
TRIP
SBIB BIT
OUT
0
0
1
1
or V
-:
BAT
, then the device will enter battery
BSW BIT
60 sec
0
1
0
1
22
DD
voltage drops below the
2
V
V
C operation in battery
Standard Mode,
Standard Mode,
SWITCHOVER
Legacy Mode,
Legacy Mode,
TRIP
TRIP
V
V
VOLTAGE
DD
DD
V
= 2.2V typ
= 2.2V typ
BAT
< V
< V
BAT
BAT
I
2
C ACTIVE IN
BACKUP?
BATTERY
Yes
Yes
NO
NO
ISL12026
WRITE/READ
IN BATTERY
BACKUP?
EE PROM
• Mode B - In this mode selection bits indicate Legacy mode
• Mode C - This mode combines Standard mode battery
• Mode D - This mode combines Legacy mode battery
Note that the IRQ/F
battery backup for all modes, allowing clocking of devices
while in battery backup mode. The pullup on the pin will
need to go to V
increase accordingly.
also powered by the battery, then the ISL12026 can
communicate in battery backup mode.
switchover combined with I
mode. When the V
device will enter battery backup mode. If the
microcontroller and bus pullups are also powered by the
battery, then the ISL12026 can communicate in battery
backup mode. This mode places the ISL12026 device in
the same operating mode as the X1226 legacy device.
switchover with no I
When the V
V
the I
drain.
switchover with no I
When the V
enter battery backup mode and the I
disabled, minimizing V
NO
NO
NO
NO
BAT
2
, then the device will enter battery backup mode and
C interface will be disabled, minimizing V
pullup to V
pullup to V
pullup to V
pullup to V
YES, needs
YES, needs
YES, needs
YES, needs
DD
DD
FREQ/IRQ
ACTIVE?
BAT
voltage drops below the lower of V
voltage drops below V
, and thus battery mode current draw will
OUT
DD
2
2
BAT
BAT
BAT
BAT
C operation in battery backup mode.
C operation in battery backup mode.
open drain output pin is active in
voltage drops below V
BAT
V
V
to operate in Battery Backup.
V
needed on I2C to V
Battery Backup.
V
V
V
BAT
TRIP
BAT
BAT
TRIP
BAT
current drain.
2
C operation in battery backup
.Pullups needed on I2C to V
.
switchover at lower of V
switchover at <V
switchover at lower of V
switchover at <V
2
C interface will be
BAT
NOTES
, the device will
BAT
DD
DD
BAT
to operate in
BAT
. Pullups
.
, the
April 13, 2006
TRIP
current
BAT
BAT
FN8231.3
BAT
or
or
or