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參數(shù)資料
| 型號： | DS12887 |
| 廠商： | DALLAS SEMICONDUCTOR |
| 元件分類： | Timer or RTC |
| 英文描述： | 1 TIMER(S), REAL TIME CLOCK, PDIP24 |
| 封裝： | DIP-24 |
| 文件頁數(shù)： | 13/19頁 |
| 文件大小： | 584K |
| 代理商： | DS12887 |
DS12887
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unaffected by the lower input voltage. As VCC falls below 3 volts typical, the RAM and timekeeper are
switched over to an internal lithium energy source. The timekeeping function maintains an accuracy of
±1
minute per month at 25
°C regardless of the voltage input on the V
CC pin.
MOT (Mode Select) – The MOT pin offers the flexibility to choose between two bus types. When
connected to VCC, Motorola bus timing is selected. When connected to GND or left disconnected, Intel
bus timing is selected. The pin has an internal pulldown resistance of approximately 20 k
.
SQW (Square Wave Output) – 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 1. The SQW signal can be turned on and off using the SQWE
bit in Register B. The SQW signal is not available when VCC is less than 4.25 volts, typically.
PERIODIC INTERRUPT RATE AND SQUARE
WAVE OUTPUT FREQUENCY Table 1
SELECT BITS REGISTER A
RS3
RS2
RS1
RS0
tPI PERIODIC
INTERRUPT RATE
SQW OUTPUT
FREQUENCY
0
None
0
1
3.90625 ms
256 Hz
0
1
0
7.8125 ms
128 Hz
0
1
122.070
s
8.192 kHz
0
1
0
244.141
s
4.096 kHz
0
1
0
1
488.281
s
2.048 kHz
0
1
0
976.5625
s
1.024 kHz
0
1
1.953125 ms
512 Hz
1
0
3.90625 ms
256 Hz
1
0
1
7.8125 ms
128 Hz
1
0
1
0
15.625 ms
64 Hz
1
0
1
31.25 ms
32 Hz
1
0
62.5 ms
16 Hz
1
0
1
125 ms
8 Hz
1
0
250 ms
4 Hz
1
500 ms
2 Hz
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 DS12887 since the
bus change from address to data occurs during the internal RAM access time. Addresses must be valid
prior to the falling edge of AS/ ALE, at which time the DS12887 latches the address from AD0 to AD6.
Valid write data must be present and held stable during the latter portion of the DS or WR pulses. In a
read cycle the DS12887 outputs 8 bits of data during the latter portion of the DS or RD pulses. The read
cycle is terminated and the bus returns to a high impedance state as DS transitions low in the case of
Motorola timing or as RD transitions high in the case of Intel timing.
AS (Address Strobe Input) – A positive-going address strobe pulse serves to demultiplex the bus. The
falling edge of AS/ALE causes the address to be latched within the DS12887. The next rising edge that
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS12887+ | 功能描述:實時時鐘 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 |
| DS12887A | 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 |
| DS12887A+ | 功能描述:實時時鐘 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 |
| DS1290 | 功能描述:計數(shù)器移位寄存器 RoHS:否 制造商:Texas Instruments 計數(shù)器類型: 計數(shù)順序:Serial to Serial/Parallel 電路數(shù)量:1 封裝 / 箱體:SOIC-20 Wide 邏輯系列: 邏輯類型: 輸入線路數(shù)量:1 輸出類型:Open Drain 傳播延遲時間:650 ns 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝:Reel |
| DS12C887 | 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 |
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