ISL1219 Intersil Corporation, ISL1219 Datasheet - Page 9

• Manufacturer Part Number: ISL1219
• Description: Real Time Clock/Calendar
• Manufacturer: Intersil Corporation

www.DataSheet4U.com
These power control situations are illustrated in Figures 11
and 12.
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 ISL1219 are active
during battery backup mode unless disabled via the control
register. The User SRAM is operational in battery backup
mode down to 1.8V.
Power Failure Detection
The ISL1219 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 ISL1219 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.
FIGURE 12. BATTERY SWITCHOVER WHEN V
FIGURE 11. BATTERY SWITCHOVER WHEN V
V
V
BAT
V
V
V
V
2
TRIP
TRIP
BAT
DD
BAT
V
DD
C bus is deactivated in battery backup mode to provide
BAT
without requiring V
- V
DD
BATHYS
V
TRIP
DD
= 5V. Low Power Mode is activated via the
and V
DD
BATTERY BACKUP
BAT
BATTERY BACKUP
. Power savings are typically
DD
).
MODE
DD
MODE
9
to drop below V
vs. V
TRIP
V
V
TRIP
BAT
is no longer
DD
+ V
BAT
TRIP
BAT
+ V
power is
BATHYS
TRIPHYS
< V
> V
. Since
3.0V
2.2V
2.2V
1.8V
TRIP
TRIP
DD
ISL1219
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 ISL1219 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 ISL1219 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
Event/Tamper Monitor and Detection
The ISL1219 provides an event detection, time stamp and
alarm function to be used in a wide variety of applications
ranging from security, warranty monitoring, data collection
and recording.
The tamper detect input pin, EVIN, can be used as a event
or tamper detection input of an external switch (mechanical
or electronic). When the EVIN pin is a valid HIGH, the
ISL1219 sets the EVT bit in the status register and, can
optionally: 1) Issue an Event output signal (EVDET pin) and
store time stamp information in on board SRAM (second,
minute, hour, date, month and year), 2) At the time event
occurred, stop the RTC registers from advancing.
To allow for flexibility of external switches used at the EVIN
pin, the internal pull-up (~1µA in full on mode) can be
disabled/enabled. This will allow more flexibility depending
on the capacitive and resistive loading at the EVIN pin.
A noise filter option is also provided for the event monitor
circuit. The EVIN pin has a time based filter where the EVIN
signal must be stable for a period of time to trigger a valid
detection. The time hysteresis filter can vary from 0, 3.9ms,
15.2ms or 31.25ms.
For low power applications the event monitor can be
sampled at a user selectable rate. The EVIN pin can be
always ON or periodically sampled with a frequency of 1/4, 1
or 2Hz.
DD
to V
DD
source. Thereafter, the device will switchover to
BAT
BAT
when V
BAT
DD
= 3V, Low Power Mode can be used.
at all times. The device will switch from
= 3.3V ±10%, V
DD
drops below V
DD
DD
BAT
= 5V and backup lithium
power is lost.
BAT
≥ 3.0V, and when
DD
, with about 50mV
line.
DD
DD
after
August 14, 2006
is normally
FN6314.1