參數(shù)資料
型號(hào)： DS17485
廠商： Maxim Integrated Products, Inc.
英文描述： 3 Volt/5 Volt Real Time Clock(3V/5V實(shí)時(shí)時(shí)鐘)
文件頁(yè)數(shù)： 2/32頁(yè)
文件大?。?/td> 236K
代理商： DS17485
DS17485/DS17487
030598 2/32
PIN DESCRIPTION
X1
X2
RCLR
AD0-AD7
PWR
KS
CS
ALE
WR
RD
IRQ
SQW
V
CC
GND
V
BAT
V
BAUX
NC
– Crystal Input
– Crystal Output
– RAM Clear Input
– Mux’ed Address/Data Bus
– Power–on Interrupt Output (open drain)
– Kickstart Input
– RTC Chip Select Input
– RTC Address Strobe
– RTC Write Data Strobe
– RTC Read Data Strobe
– Interrupt Request Output (open drain)
– Square Wave Output
– +3 or +5 Volt Main Supply
– Ground
– Battery + Supply
– Auxiliary Battery Supply
– No Connection
DESCRIPTION
The DS17485/DS17487 is a real time clock (RTC)
designed as a successor to the industry standard
DS1285, DS1385, DS1485, DS1585, and DS1685 PC
real time clocks. This device provides the industry stan-
dard DS1285 clock function with either +3.0 or +5.0 volt
operation . The DS17485 also incorporates a number of
enhanced features including a silicon serial number,
power on/off control circuitry, 114 bytes of user
NVSRAM plus 4K bytes of additional NVRAM, and
32.768 KHz output for sustaining power management
activities.
The DS17485/DS17487 power control circuitry allows
the system to be powered on via an external stimulus,
such as a keyboard or by a time and date (wake up)
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 DS17485 is a clock/calendar chip 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. The
DS17487 incorporates the DS17485 chip, a 32.768
KHz crystal, and a lithium battery in a complete, self–
contained timekeeping module. The entire unit is fully
tested at Dallas Semiconductor such that a minimum of
10 years of timekeeping and data retention in the
absence of V
CC
is guaranteed.
OPERATION
The block diagram in Figure 1 shows the pin connec-
tions with the major internal functions of the
DS17485/DS17487.
The
describe the function of each pin.
following
paragraphs
SIGNAL DESCRIPTIONS
GND, V
CC
–
DC power is provided to the device on
these pins. V
CC
is the +3 volt or +5 volt input.
SQW (Square Wave Output)
–
The SQW pin will pro-
vide a 32 KHz square wave output, t
REC
, after a pow-
er–up condition has been detected. This condition sets
the following bits, enabling the 32 KHz output; DV1=1,
and E32K=1. A square wave will be output on this pin if
either SQWE=1 or E32K=1. If E32K=1, then 32 KHz will
be output regardless of the other control bits. If E32K=0,
then the output frequency is dependent on the control
bits in register A. The SQW pin can output a signal from
one of 13 taps provided by the 15 internal divider stages
of the real time clock. The frequency of the SQW pin can
be changed by programming Register A as shown in
Table 2. The SQW signal can be turned on and off using
the SQWE bit in register B or the E32K bit in extended
register 4Bh. A 32 KHz SQW signal is output when the
Enable 32 KHz (E32K) bit in extended register 4Bh is a
logic one, and V
CC
is above V
PF
. A 32 KHz square wave
is also available when V
CC
is less than V
PF
if E32K=1,
ABE=1, and voltage is applied to the V
BAUX
pin.
AD0–AD7 (Multiplexed Bidirectional Address/Data
Bus)
–
Multiplexed buses save pins because address
information and data information time share the same
signal paths. The addresses are present during the first
portion of the bus cycle and the same pins and signal
paths are used for data in the second portion of the
cycle. Address/data multiplexing does not slow the
access time of the DS17485 since the bus change from
address to data occurs during the internal RAM access
time. Addresses must be valid prior to the latter portion
of ALE, at which time the DS17485/DS17487 latches
the address. Valid write data must be present and held
stable during the latter portion of the WR pulse. In a read
cycle the DS17485/DS17487 outputs 8 bits of data dur-
ing the latter portion of the RD pulse. The read cycle is
terminated and the bus returns to a high impedance
state as RD transitions high. The address/data bus also
serves as a bidirectional data path for the external
extended RAM.
相關(guān)PDF資料
PDF描述
DS1775 SOT23 Digital Thermometer and Thermostat(SOT23數(shù)字溫度計(jì)和恒溫控制器)
DS1800 Dual Inverting Log Gain/Attenuator(雙路反相對(duì)數(shù)放大/衰減器)
DS1801 Dual Audio Taper Potentiometer(雙路音頻抽頭電位器)
DS1802 Dual Audio Taper Potentiometer with Push Button Control(帶按鈕控制的雙路音頻抽頭電位器)
DS1803 Addressable Dual Digital Potentiometer(可尋址雙路數(shù)字電位器)
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
DS17485-3 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
DS17485-3+ 功能描述:實(shí)時(shí)時(shí)鐘 3V/5V RTC 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
DS17485-5 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
DS17485-5+ 功能描述:實(shí)時(shí)時(shí)鐘 3V/5V RTC 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
DS1748555 制造商:Maxim Integrated Products 功能描述:
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。

采購(gòu)需求

(若只采購(gòu)一條型號(hào)，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

*型號(hào) *數(shù)量 廠商 批號(hào) 封裝
添加更多采購(gòu)

我的聯(lián)系方式

*
*
*