DS1323 Maxim, DS1323 Datasheet - Page 4

• Manufacturer Part Number: DS1323
• Description: The DS1323 flexible nonvolatile controller with lithium battery monitor is a CMOS circuit that solves the application problem of converting CMOS SRAMs into nonvolatile memory
• Manufacturer: Maxim

BATTERY VOLTAGE MONITORING
The DS1323 automatically performs periodic battery voltage monitoring at a factory-programmed time
interval of 24 hours. Such monitoring begins within t
power failure occurs.
After each 24-hour period (t
(R
voltage trip point (V
be performed with period t
active until the battery is physically removed and replaced by a fresh cell. The battery is still retested after
each V
than V
output driver.
Battery replacement following
lost. During battery replacement, the minimum time duration between old battery detachment and new
battery attachment (t
Should
clear
NOTE: The DS1323 cannot constantly monitor an attached battery because such monitoring would
drastically reduce the life of the battery. As a result, the DS1323 only tests the battery for one second out of
every 24 hours and does not monitor the battery in any way between tests. If a good battery (one that has not
been previously flagged with
the removal and may not activate
the DS1323, the battery may not be tested until the next scheduled test.
NOTE: Battery monitoring is only a useful technique when testing can be done regularly over the entire life
of a lithium battery. Because the DS1323 only performs battery monitoring when V
which are powered down for excessively long periods can completely drain their lithium cells without
receiving any advanced warning. To prevent such an occurrence, systems using the DS1323 battery
monitoring feature should be powered up periodically (at least once every few months) in order to perform
battery testing. Furthermore, anytime
should be checked via checksum or other technique.
POWER MONITORING
The DS1323 automatically detects out-of-tolerance power supply conditions and warns a processor-based
system of impending power failure. When V
(10% tolerance) (V
for 200ms nominal (t
transients and to allow t
FRESHNESS SEAL MODE
When the battery is first attached to the DS1323 without V
immediately provide battery-backup power on V
Freshness Seal Mode. This mode allows a battery to be attached during manufacturing but not used until
RST
INT
) for one second (t
also serves as a power-on reset during power-up. After V
BW
BTP
CC
BW
.
power-up, however, even if
during such testing,
not deactivate for this reason, the new battery can be detached for t
CCTP
BTP
BDBA
RPU
), the V
), the battery warning output
REC
BTPW
). This reset period is sufficiently long to prevent system operation during power-on
) must be met or
to expire.
BTCW
). During this one second, if V
BTCN
BW
CCI
BW
BW
) has elapsed, the DS1323 connects V
) is removed between battery tests, the DS1323 may not immediately sense
to detect battery removal and replacement. Once asserted,
comparator activates the reset signal
BW
is deasserted and regular 24-hour testing resumes.
activation is normally done with V
RST
BW
until the next scheduled battery test. If a battery is then reattached to
BW
is activated on the first battery test after a power-up, data integrity
has an open-drain output driver.
BW
was active on power-down. If the battery is found to be higher
CCI
will not deactivate following attachment of the new battery.
falls below the trip point level in the range of 3.0 to 2.8 volts
CCO
4 of 14
. Only after V
REC
BW
after V
is asserted. While
BAT
CCI
falls below the factory-programmed battery
CCI
CC
CCI
rises above V
exceeds V
power applied, the device does not
exceeds V
CCI
RST
BAT
nominal so that SRAM data is not
.
BW
to an internal 1MΩ test resistor
CCTP
is active, battery testing will
BDBA
CCTP
CCTP
,
RST
and then re-attached to
and is suspended when
CC
will the DS1323 leave
BW
is nominal, systems
will be held active
has an open-drain
BW
remains
DS1323