ISL1208IRT8Z-TK Intersil, ISL1208IRT8Z-TK Datasheet - Page 9

• Manufacturer Part Number: ISL1208IRT8Z-TK
• Description: IC RTC/CALENDER I2C 8-TDFN
• Manufacturer: Intersil
• Type: Clock/Calendar/NVSRAMr

Specifications of ISL1208IRT8Z-TK

• Memory Size: 2B
• Time Format: HH:MM:SS (12/24 hr)
• Date Format: YY-MM-DD-dd
• Interface: I²C, 2-Wire Serial
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-TDFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

the ISL1208 for up to 10 years. Another option is to use a
Super Cap for applications where V
to a month. See the “Application Section” on page 18 for
more information.
Normal Mode (V
(V
To transition from the V
following conditions must be met:
Condition 1:
Condition 2:
Battery Backup Mode (V
(V
The ISL1208 device will switch from the V
when one of the following conditions occurs:
Condition 1:
Condition 2:
These power control situations are illustrated in Figures 9
and 10.
BAT
DD
FIGURE 10. BATTERY SWITCHOVER WHEN V
V
where V
V
where V
V
where V
V
where V
FIGURE 9. BATTERY SWITCHOVER WHEN V
V
V
V
V
DD
DD
DD
DD
V
V
TRIP
TRIP
BAT
DD
BAT
)
V
DD
)
BAT
< V
< V
> V
> V
- V
BATHYS
TRIP
BATHYS
TRIPHYS
BAT
TRIP
BAT
TRIP
BATHYS
V
TRIP
- V
+ V
≈ 2.2V
+ V
BATHYS
DD
BATHYS
≈ 50mV
≈ 50mV
TRIPHYS
≈ 30mV
) to Battery Backup Mode
BATTERY BACKUP
DD
BATTERY BACKUP
to V
MODE
BAT
MODE
9
BAT
) to Normal Mode
mode, both of the
DD
is interrupted for up
V
BAT
V
BAT
TRIP
BAT
to V
+ V
BAT
+ V
BATHYS
TRIPHYS
< V
DD
> V
3.0V
2.2V
2.2V
1.8V
TRIP
TRIP
mode
ISL1208
The I
lower power. Aside from this, all RTC functions are
operational during battery backup mode. Except for SCL and
SDA, all the inputs and outputs of the ISL1208 are active
during battery backup mode unless disabled via the control
register. The User SRAM is operational in battery backup
mode down to 2V.
Power Failure Detection
The ISL1208 provides a Real Time Clock Failure Bit (RTCF)
to detect total power failure. It allows users to determine if
the device has powered up after having lost all power to the
device (both V
Low Power Mode
The normal power switching of the ISL1208 is designed to
switch into battery backup mode only if the V
lost. This will ensure that the device can accept a wide range
of backup voltages from many types of sources while reliably
switching into backup mode. Another mode, called Low
Power Mode, is available to allow direct switching from V
to V
the additional monitoring of V
needed, that circuitry is shut down and less power is used
while operating from V
600nA at V
LPMODE bit in the control and status registers.
Low Power Mode is useful in systems where V
higher than V
V
of hysteresis to prevent any switchback of V
switchover. In a system with a V
battery of V
However, it is not recommended to use Low Power Mode in
a system with V
there is a finite I-R voltage drop in the V
InterSeal™ Battery Saver
The ISL1208 has the InterSeal™ Battery Saver which
prevents initial battery current drain before it is first used. For
example, battery-backed RTCs are commonly packaged on
a board with a battery connected. In order to preserve
battery life, the ISL1208 will not draw any power from the
battery source until after the device is first powered up from
the V
battery backup mode whenever V
Real Time Clock Operation
The Real Time Clock (RTC) uses an external 32.768kHz quartz
crystal to maintain an accurate internal representation of
second, minute, hour, day of week, date, month, and year. The
RTC also has leap-year correction. The clock also corrects for
months having fewer than 31 days and has a bit that controls
24-hour or AM/PM format. When the ISL1208 powers up after
the loss of both V
incrementing until at least one byte is written to the clock
register.
DD
BAT
2
to V
DD
C bus is deactivated in battery backup mode to provide
without requiring V
BAT
source. Thereafter, the device will switchover to
DD
BAT
when V
BAT
DD
= 5V. Low Power Mode is activated via the
DD
= 3V, Low Power Mode can be used.
DD
at all times. The device will switch from
and V
= 3.3V ±10%, V
and V
DD
DD
BAT
drops below V
. Power savings are typically
BAT
DD
).
, the clock will not begin
DD
to drop below V
DD
vs V
DD
BAT
= 5V and backup lithium
TRIP
power is lost.
BAT
≥ 3.0V, and when
DD
, with about 50mV
is no longer
line.
DD
DD
DD
September 12, 2008
TRIP
after
power is
is normally
. Since
FN8085.8
DD