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參數(shù)資料
| 型號： | DS2450 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | 1-Wire Quad A/D Converter(1線串行四路A/D轉(zhuǎn)換器) |
| 中文描述： | 四路、1-Wire A/D轉(zhuǎn)換器 |
| 文件頁數(shù)： | 11/23頁 |
| 文件大?。?/td> | 165K |
| 代理商： | DS2450 |
DS2450
091598 11/23
1–WIRE BUS SYSTEM
The 1–Wire bus is a system which has a single bus mas-
ter and one or more slaves. In all instances the DS2450
is a slave device. The discussion of this bus system is
broken down into three topics: hardware configuration,
transaction sequence, and 1–Wire signaling (signal
types and timing). A 1–Wire protocol defines bus trans-
actions in terms of the bus state during specific time
slots that are initiated on the falling edge of sync pulses
from the bus master. For a more detailed protocol
description, refer to Chapter 4 of the Book of DS19xx
iButton Standards.
HARDWARE CONFIGURATION
The 1–Wire bus has only a single line by definition; it is
important that each device on the bus be able to drive it
at the appropriate time. To facilitate this, each device
attached to the 1–Wire bus must have open drain or
3–state outputs. The 1–Wire port of the DS2450 is open
drain with an internal circuit equivalent to that shown in
Figure 8. A multidrop bus consists of a 1–Wire bus with
multiple slaves attached. At regular speed the 1–Wire
bus has a maximum data rate of 16.3k bits per second.
The speed can be boosted to 142k bits per second by
activating the Overdrive Mode. The 1–Wire bus
requires a pull–up resistor of approximately 5k
. A
resistor of no more than 2.2k
allows for parasite–pow-
ered conversion without a strong pull–up.
The idle state for the 1–Wire bus is high. If for any reason
a transaction needs to be suspended, the bus MUST be
left in the idle state if the transaction is to resume. If this
does not occur and the bus is left low for more than 16
μ
s
(Overdrive Speed) or more than 120
μ
s (regular speed),
one or more devices on the bus may be reset.
HARDWARE CONFIGURATION
Figure 8
V
PUP
DS2450 1–WIRE PORT
RX
TX
100 OHM
MOSFET
1.5 k
MicroLAN
RX
TX
RX
=
RECEIVE
TX
=
TRANSMIT
5
μ
A
TYP.
BUS MASTER
OPEN DRAIN
PORT PIN
PIN 3
DATA
TRANSACTION SEQUENCE
The protocol for accessing the DS2450 via the 1–Wire
port is as follows:
Initialization
ROM Function Command
Memory/Convert Function Command
Transaction/Data
INITIALIZATION
All transactions on the 1–Wire bus begin with an initial-
ization sequence. The initialization sequence consists
of a reset pulse transmitted by the bus master followed
by presence pulse(s) transmitted by the slave(s).
The presence pulse lets the bus master know that the
DS2450 is on the bus and is ready to operate. For more
details, see the “1–Wire Signaling” section.
ROM FUNCTION COMMANDS
Once the bus master has detected a presence, it can
issue one of the seven ROM function commands. All
ROM function commands are eight bits long. A list of
these commands follows (refer to flowchart in Figure 9):
Read ROM [33H]
This command allows the bus master to read the
DS2450’s 8–bit family code, unique 48–bit serial num-
ber, and 8–bit CRC. This command can only be used if
there is a single DS2450 on the bus. If more than one
slave is present on the bus, a data collision will occur
when all slaves try to transmit at the same time (open
drain will produce a wired–AND result). The resultant
family code and 48–bit serial number will result in a mis-
match of the CRC.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS2450S | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| DS2450S/T&R | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| DS2450S+ | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC Quad 1-Wire RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| DS2450S+ | 制造商:Maxim Integrated Products 功能描述:SEMICONDUCTOR ((NW)) |
| DS2450S+T&R | 制造商:Maxim Integrated Products 功能描述:IC CONVERTER A/D QUAD 1-W 8-SOIC |
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