参数资料
型号: DS1345YG-70-IND
厂商: Maxim Integrated Products, Inc.
英文描述: 1024k Nonvolatile SRAM with Battery Monitor
中文描述: 1024k非易失SRAM与电池监视器
文件页数: 2/12页
文件大小: 229K
代理商: DS1345YG-70-IND
DS1345Y/AB
2 of 12
READ MODE
The DS1345 devices execute a read cycle whenever
WE
(Write Enable) is inactive (high) and
CE
(Chip
Enable) and
OE
(Output Enable) are active (low). The unique address specified by the 17 address inputs
(A
0
– A
16
) defines which of the 131,072 bytes of data is to be accessed. Valid data will be available to the
eight data output drivers within t
ACC
(Access Time) after the last address input signal is stable, providing
that
CE
and
OE
(Output Enable) access times are also satisfied. If
OE
and
CE
access times are not
satisfied, then data access must be measured from the later-occurring signal (
CE
or
OE
) and the limiting
parameter is either t
CO
for
CE
or t
OE
for
OE
rather than address access.
WRITE MODE
The DS1345 devices execute a write cycle whenever the
WE
and
CE
signals are in the active (low) state
after address inputs are stable. The later-occurring falling edge of
CE
or
WE
will determine the start of
the write cycle. The write cycle is terminated by the earlier rising edge of
CE
or
WE
. All address inputs
must be kept valid throughout the write cycle.
WE
must return to the high state for a minimum recovery
time (t
WR
) before another cycle can be initiated. The
OE
control signal should be kept inactive (high)
during write cycles to avoid bus contention. However, if the output drivers are enabled (
CE
and
OE
active) then
WE
will disable the outputs in t
ODW
from its falling edge.
DATA RETENTION MODE
The DS1345AB provides full functional capability for V
CC
greater than 4.75V and write protects by 4.5V.
The DS1345Y provides full functional capability for V
CC
greater than 4.5V and write protects by 4.25V.
Data is maintained in the absence of V
CC
without any additional support circuitry. The nonvolatile static
RAMs constantly monitor V
CC
. Should the supply voltage decay, the NV SRAMs automatically write
protect themselves, all inputs become “don’t care,” and all outputs become high impedance. As V
CC
falls
below approximately 2.7V, the power switching circuit connects the lithium energy source to RAM to
retain data. During power-up, when V
CC
rises above approximately 2.7V, the power switching circuit
connects external V
CC
to the RAM and disconnects the lithium energy source. Normal RAM operation
can resume after V
CC
exceeds 4.75V for the DS1345AB and 4.5V for the DS1345Y.
SYSTEM POWER MONITORING
DS1345 devices have the ability to monitor the external V
CC
power supply. When an out-of-tolerance
power supply condition is detected, the NV SRAMs warn a processor-based system of impending power
failure by asserting
RST
. On power-up,
RST
is held active for 200ms nominal to prevent system
operation during power-on transients and to allow t
REC
to elapse.
RST
has an open drain output driver.
BATTERY MONITORING
The DS1345 devices automatically perform periodic battery voltage monitoring on a 24-hour time
interval. Such monitoring begins within t
REC
after V
CC
rises above V
TP
and is suspended when power
failure occurs.
After each 24-hour period has elapsed, the battery is connected to an internal 1M
=
test resistor for one
second. During this one second, if battery voltage falls below the battery voltage trip point (2.6V), the
battery warning output
BW
is asserted. Once asserted,
BW
remains active until the module is replaced.
The battery is still retested after each V
CC
power-up, however, even if
BW
is active. If the battery voltage
is found to be higher than 2.6V during such testing,
BW
is de-asserted and regular 24-hour testing
resumes.
BW
has an open drain output driver.
相关PDF资料
PDF描述
DS1350AB 4096K Nonvolatile SRAM with Battery Monitor(带电池监控的 4096K非易失性SRAM)
DS1350Y 4096K Nonvolatile SRAM with Battery Monitor(带电池监控的4096K非易失性SRAM)
DS1350W 3.3V 4096K Nonvolatile SRAM with Battery Monitor(带电池监控的3.3V 4096K非易失性SRAM)
DS1371 2-Wire, 32-Bit Binary Counter Watchdog Clock
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