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參數(shù)資料
| 型號： | DS1994 |
| 英文描述： | 4kb Plus Time Memory iButton |
| 中文描述： | 4K位、帶有時鐘的存儲器iButton® |
| 文件頁數(shù)： | 3/22頁 |
| 文件大小： | 254K |
| 代理商： | DS1994 |
DS1994
Figure 1. DS1994 BLOCK DIAGRAM
3 of 22
SRAM
16 PAGES of
256-BITs
TIMEKEEPING
FUNCTIONS
HOLDING REGISTERS
& COUNTERS
INTERNAL REGISTERS
32.768 kHz
OSCILLATOR
256-BIT
SCRATCHPAD
1-W
ROM
CONTROL
FUNCTION
64-BIT
LASERED
ROM
PARASITE-
POWERED
CIRCUITRY
MEMORY
FUNCTION
CONTROL
1-WIRE
PORT
3V LITHIUM
PARASITE POWER
The block diagram (Figure 1) shows the parasite-powered circuitry. This circuitry steals power whenever
the data input is high. The data line provides sufficient power as long as the specified timing and voltage
requirements are met. The advantages of parasite power are two-fold: 1) by parasiting off this input,
lithium is conserved, and 2) if the lithium is exhausted for any reason, the ROM can still be read
normally.
64-BIT LASERED ROM
Each DS1994 contains a unique ROM code that is 64 bits long. The first 8 bits are a 1-Wire family code.
The next 48 bits are a unique serial number. The last 8 bits are a CRC of the first 56 bits. (See Figure 2.)
The 1-Wire CRC is generated using a polynomial generator consisting of a shift register and XOR gates,
as shown in Figure 3. The polynomial is X
8
+ X
5
+ X
4
+ 1. Additional information about the Dallas 1-Wire
Cyclic Redundancy Check is available in the Book of DS19xx iButton Standards. The shift register bits
are initialized to zero. Then starting with the least significant bit of the family code, 1 bit at a time is
shifted in. After the 8th bit of the family code has been entered, then the serial number is entered. After
the 48th bit of the serial number has been entered, the shift register contains the CRC value. Shifting in
the 8 bits of CRC should return the shift register to all zeros.
Figure 2. 64-BIT LASERED ROM
MSB
LSB
8-Bit CRC Code
48-Bit Serial Number
8-Bit Family Code (04h)
MSB
LSB
MSB
LSB
MSB
LSB
相關PDF資料 |
PDF描述 |
|---|---|
| DS1995 | 16-kbit Memory iButton |
| DS1995L-F5 | 16-kbit Memory iButton |
| DS1996 | 64kbit Memory iButtonTM |
| DS1996L-F5 | 64kbit Memory iButtonTM |
| DS2004SF24 | Rectifier Diode |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| DS1994-LF5 | 制造商: 功能描述: 制造商:undefined 功能描述: |
| DS1994L-F5 | 功能描述:iButton RoHS:否 存儲類型:SRAM 存儲容量:512 B 組織: 工作電源電壓:3 V to 5.25 V 接口類型:1-Wire 最大工作溫度:+ 85 C 尺寸:17.35 mm x 5.89 mm 封裝 / 箱體:F5 MicroCan 制造商:Maxim Integrated |
| DS1994L-F5+ | 功能描述:iButton RoHS:否 存儲類型:SRAM 存儲容量:512 B 組織: 工作電源電壓:3 V to 5.25 V 接口類型:1-Wire 最大工作溫度:+ 85 C 尺寸:17.35 mm x 5.89 mm 封裝 / 箱體:F5 MicroCan 制造商:Maxim Integrated |
| DS1994L-F5-W | 功能描述:iButton RoHS:否 存儲類型:SRAM 存儲容量:512 B 組織: 工作電源電壓:3 V to 5.25 V 接口類型:1-Wire 最大工作溫度:+ 85 C 尺寸:17.35 mm x 5.89 mm 封裝 / 箱體:F5 MicroCan 制造商:Maxim Integrated |
| DS1994-LFS | 制造商: 功能描述: 制造商:undefined 功能描述: |
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