參數(shù)資料
型號(hào)： DS1921
英文描述： High-Resolution Thermochron iButton
中文描述： 高分辨率Thermochron iButton的
文件頁(yè)數(shù)： 3/44頁(yè)
文件大?。?/td> 271K
代理商： DS1921
DS1921H/Z
3 of 44
DS1921H/Z BLOCK DIAGRAM
Figure 1
Internal
Timekeeping &
Control Reg. &
Counters
3V Lithium
General-Purpose
SRAM
Register Page
Alarm Time Stamp
and Duration
Logging Memory
Datalog
Memory
Histogram Memory
32.768kHz
Oscillator
Control
Logic
Temperature
Sensor
256-Bit
Scratchpad
Memory
Function
Control
ROM
Function
Control
64-Bit
Lasered
ROM
Parasite
Powered
Circuitry
1-Wire
Port
IO
PARASITE POWER
The block diagram (Figure 1) shows the parasite-powered circuitry. This circuitry “steals” power when-
ever the IO input is high. IO will provide sufficient power as long as the specified timing and voltage re-
quirements 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 may still be read normally.
64-BIT LASERED ROM
Each DS1921 contains a unique ROM code that is 64 bits long. The first eight bits are a 1-Wire family
code. The next 36 bits are a unique serial number. The next 12 bits, called temperature range code, allow
distinguishing the DS1921H and DS1921Z from each other and from other DS1921 versions. The last
eight bits are a CRC of the first 56 bits. See Figure 3 for details. The 1-Wire CRC is generated using a
polynomial generator consisting of a shift register and XOR gates as shown in Figure 4. The polynomial
is X
8
+ X
5
+ X
4
+ 1. Additional information about the Dallas 1-Wire Cyclic Redundancy Check is avail-
able in
Application Note 27
and in the
Book of DS19xx iButton Standards
.
The shift register bits are initialized to 0. Then starting with the least significant bit of the family code,
one bit at a time is shifted in. After the eighth
bit of the family code has been entered, then the serial
number followed by the temperature range code is entered. After the range code has been entered, the
shift register contains the CRC value. Shifting in the eight bits of CRC returns the shift register to all 0s.
相關(guān)PDF資料
PDF描述
DS1921H-F5 High-Resolution Thermochron iButton
DS1921Z-F5 High-Resolution Thermochron iButton
DS1963L-F5 NVRAM (Battery Based)
DS1963S SHA iButton
DS1971 256-Bit EEPROM iButton
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
DS1921G 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Thermochron iButton
DS1921G_11 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:Logs Up to 2048 Consecutive Temperature Thermochron iButton
DS1921G_1109 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:Thermochron iButton
DS1921G_12 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:Thermochron iButton
DS1921G-F5 功能描述:iButton RoHS:否 存儲(chǔ)類型:SRAM 存儲(chǔ)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
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