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參數(shù)資料
| 型號： | DS17285S-5 |
| 廠商： | DALLAS SEMICONDUCTOR |
| 元件分類： | Timer or RTC |
| 英文描述： | 1 TIMER(S), REAL TIME CLOCK, PDSO24 |
| 封裝： | SOIC-24 |
| 文件頁數(shù)： | 23/38頁 |
| 文件大小： | 415K |
| 代理商： | DS17285S-5 |
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DS17285/DS17287
3 of 38
The DS17285/DS17287 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 DS17285 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 DS17287 incorporates the DS17285 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 VCC is guaranteed.
OPERATION
The block diagram in Figure 1 shows the pin connections with the major internal functions of the
DS17285/DS17287. The following paragraphs describe the function of each pin.
SIGNAL DESCRIPTIONS
GND, VCC - DC power is provided to the device on these pins. VCC is the +3-volt or +5-volt input.
SQW (Square Wave Output) - The SQW pin will provide a 32 kHz square wave output, tREC, after a
power-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 VCC is above VPF.
A 32 kHz square wave is also available when VCC is less than VPF if E32K=1, ABE=1, and voltage is
applied to the VBAUX pin.
AD0-AD7 (Multiplexed Bi-directional 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 DS17285 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 DS17285/DS17287 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
DS17285/DS17287 outputs 8 bits of data during 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 bi-directional data path for the external extended RAM.
ALE (RTC Address Strobe Input; active high) - A pulse on the address strobe pin serves to
demultiplex the bus. The falling edge of ALE causes the RTC address to be latched within the
DS17285/DS17287.
RD
(RTC Read Input; active low) - RD identifies the time period when the DS17285/DS17287 drives
the bus with RTC read data. The RD signal is an enable signal for the output buffers of the clock.
相關(guān)PDF資料 |
PDF描述 |
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| DS17285SN-5 | 1 TIMER(S), REAL TIME CLOCK, PDSO24 |
| DS17285EN-3 | 1 TIMER(S), REAL TIME CLOCK, PDSO28 |
| DS17285S-3 | 1 TIMER(S), REAL TIME CLOCK, PDSO24 |
| DS1742-100 | 0 TIMER(S), REAL TIME CLOCK, PDIP24 |
| DS1742W-120 | 0 TIMER(S), REAL TIME CLOCK, PDIP24 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS17285S-5/T&R | 制造商:Maxim Integrated Products 功能描述:IC RTC 5V 2K NV RAM 24-SOIC |
| DS17285S-5/T&R | 功能描述:實時時鐘 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 時間格式:HH:MM:SS RTC 存儲容量: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 |
| DS17285S-5+ | 功能描述:實時時鐘 3V/5V RTC K Multiplexed Kick-S 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 時間格式:HH:MM:SS RTC 存儲容量: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 |
| DS17285S-5+T&R | 制造商:Maxim Integrated Products 功能描述:REAL TIME CLOCK MULTIPLEXED 2KBYTE 24SOIC - Tape and Reel 制造商:Maxim Integrated Products 功能描述:Maxim Integrated DS17285S-5+T&R Real Time Clocks (RTC) 制造商:Maxim Integrated Products 功能描述:IC RTC 5V 2K NV RAM 24-SOIC |
| DS17285S-5+T&R | 功能描述:實時時鐘 3V/5V RTC K Multiplexed Kick-S 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 時間格式:HH:MM:SS RTC 存儲容量: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 |
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