參數(shù)資料
型號(hào)： DS1501WEN
英文描述： Y2K-Compliant Watchdog Real-Time Clocks
中文描述： 千年蟲的看門狗實(shí)時(shí)時(shí)鐘
文件頁(yè)數(shù)： 11/20頁(yè)
文件大?。?/td> 265K
代理商： DS1501WEN
DS1501/DS1511 Y2KC Watchdog Real-Time Clocks
11 of 20
DETAILED DESCRIPTION
The RTC registers are double buffered into an internal and external set. The user has direct access to the external
set. Clock/calendar updates to the external set of registers can be disabled and enabled to allow the user to access
static data. When the crystal oscillator is turned on, the internal set of registers are continuously updated; this
occurs regardless of external register settings to guarantee that accurate RTC information is always maintained.
The DS1501/DS1511 contain their own power-fail circuitry that automatically deselects the device when the V
CC
supply falls below a power-fail trip point. This feature provides a high degree of data security during unpredictable
system operation caused by low V
CC
levels.
The DS1501/DS1511 have interrupt (
IRQ
), power control (
PWR
), and reset (
RST
) outputs that can be used to
control CPU activity. The
IRQ
interrupt or
RST
outputs can be invoked as the result of a time-of-day alarm, CPU
watchdog alarm, or a kickstart signal. The DS1501/DS1511 power-control circuitry allow the system to be powered
on by an external stimulus, such as a keyboard or by a time and date (wakeup) alarm. The
PWR
output pin can be
triggered by one or either of these events, and can be used to turn on an external power supply. The
PWR
pin is
under software control, so that when a task is complete, the system power can then be shut down. The
DS1501/DS1511 power-on reset can be used to detect a system power-down or failure and hold the CPU in a safe
reset state until normal power returns and stabilizes; the
RST
output is used for this function.
The DS1501/DS1511 are clock/calendar chips with the features described above. An external crystal and battery
are the only components required to maintain time-of-day and memory status in the absence of power.
Table 1. RTC Operating Modes
CE
OE
WE
DQ0–DQ7
V
IH
X
X
High-Z
V
IL
X
V
IL
D
IN
V
IL
V
IL
V
IH
D
OUT
V
IL
V
IH
V
IH
High-Z
V
SO
< V
CC
< V
PF
X
X
X
High-Z
V
CC
V
SO
< V
PF
X
X
X
High-Z
DATA READ MODE
The DS1501/DS1511 are in read mode whenever
CE
(chip enable) and
OE
(output enable) are low and
WE
(write
enable) is high. The device architecture allows ripple-through access to any valid address location. Valid data is
available at the DQ pins within t
AA
(address access) after the last address input is stable, provided that
CE
and
OE
access times are satisfied. If
CE
or
OE
access times are not met, valid data is available at the latter of chip-enable
access (t
CSA
) or at output-enable access time (t
OEA
). The state of the data input/output pins (DQ) is controlled by
CE
and
OE
. If the outputs are activated before t
AA
, the data lines are driven to an intermediate state until t
AA
. If the
address inputs are changed while
CE
and
OE
remain valid, output data remains valid for output-data hold time (t
OH
)
but then goes indeterminate until the next address access (Table 1).
DATA WRITE MODE
The DS1501/DS1511 are in write mode whenever
CE
and
WE
are in their active state. The start of a write is
referenced to the latter occurring transition of
CE
or
WE
. The addresses must be held valid throughout the cycle.
CE
or
WE
must return inactive for a minimum of t
WR
prior to the initiation of a subsequent read or write cycle. Data
in must be valid t
DS
prior to the end of the write and remain valid for t
DH
afterward. In a typical application, the
OE
signal is high during a write cycle. However,
OE
can be active provided that care is taken with the data bus to avoid
bus contention. If
OE
is low prior to a high-to-low transition on
WE
, the data bus can become active with read data
defined by the address inputs. A low transition on
WE
then disables the outputs t
WEZ
after
WE
goes active (Table 1).
V
CC
A0–A4
X
A
IN
A
IN
A
IN
X
X
MODE
Deselect
Write
Read
POWER
Standby
Active
Active
In tolerance
Read
Deselect
Data Retention
Active
CMOS Standby
Battery Current
相關(guān)PDF資料
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
DS1501WEN/T&R 制造商:Rochester Electronics LLC 功能描述: 制造商:DSC 功能描述:
DS1501WEN/T&R 功能描述:實(shí)時(shí)時(shí)鐘 RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時(shí)間格式:HH:MM:SS RTC 存儲(chǔ)容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube
DS1501WEN/TR 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:Y2K-Compliant Watchdog Real-Time Clocks
DS1501WEN+ 功能描述:實(shí)時(shí)時(shí)鐘 Y2K-Compliant Watchdog RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時(shí)間格式:HH:MM:SS RTC 存儲(chǔ)容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube
DS1501WEN+T&R 制造商:Maxim Integrated Products 功能描述:REAL TIME CLOCK PARALLEL 256BYTE 28TSOP - Tape and Reel 制造商:Maxim Integrated Products 功能描述:IC RTC WDOG Y2K 3.3V IND 28-TSOP 制造商:Maxim Integrated Products 功能描述:Real Time Clock Y2K-Compliant Watchdog
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