參數(shù)資料
型號(hào)： 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(yè)數(shù)： 10/23頁(yè)
文件大?。?/td> 165K
代理商： DS2450
DS2450
091598 10/23
CONVERT [3CH]
The Convert command is used to initiate the analog to
digital conversion for one or more channels at the reso-
lution specified in memory page 1, control/status data.
The conversion takes between 60 and 80
μ
s per bit plus
an offset time of maximum 160
μ
s every time the convert
command is issued. For four channels with 12–bit reso-
lution each, as an example, the convert command will
not take more than 4
×
12
×
80
μ
s plus 160
μ
s offset, which
totals 4 ms. If the DS2450 gets its power through the
V
CC
pin, the bus master may communicate with other
devices on the 1–Wire bus while the DS2450 is busy
with A/D conversions. If the device is powered entirely
from the 1–Wire bus, the bus master must instead pro-
vide a strong pull–up to 5V for the estimated duration of
the conversion in order to provide sufficient energy.
The conversion is controlled by the input select mask
(Figure 7a) and the read–out control byte (Figure 7b). In
the input select mask the bus master specifies which
channels participate in the conversion. A channel is
selected if the bit associated to the channel is set to 1. If
more than one channel is selected, the conversion
takes place one channel after another in the sequence
A, B, C, D, skipping those channels that are not
selected. The bus master can read the result of a chan-
nel’s conversion before the conversion of all the remain-
ing selected channels is completed. In order to distin-
guish between the previous result and the new value the
bus master uses the read–out control byte. This byte
allows presetting the conversion read–out registers for
each selected channel to all 1’s or all 0’s. If the expected
result is close to 0 then one should preset to all 1’s or to
all 0’s if the conversion result will likely be a high number.
In applications where the bus master can wait until all
selected channels are converted before reading, a pre-
set of the read–out registers is not necessary.
Note
that
for a channel not selected in the input select mask, the
channel’s read–out control setting has no effect. If a
channel constantly yields conversion results close to 0
the channel’s output transistor may be conducting. See
section Device Registers for details.
INPUT SELECT MASK (CONVERSION COMMAND)
Figure 7a
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
“don’t care”
D
C
B
A
READ–OUT CONTROL (CONVERSION COMMAND)
Figure 7b
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
Set D
Clear D
Set C
Clear C
Set B
Clear B
Set A
Clear A
Set
Clear
Explanation
0
0
no preset, leave as is
0
1
preset to all 0’s
1
0
preset to all 1’s
1
1
(illegal code)
Following the Convert command byte the bus master
transmits the input select mask and the read–out control
byte. Now the bus master reads the CRC16 of the com-
mand byte, select mask and control byte. The conver-
sion will start no earlier than 10
μ
s after the most signifi-
cant bit of the CRC is received by the bus master.
With a parasitic power supply the bus master must acti-
vate the strong pull–up within this 10
μ
s window for a
duration that is estimated as explained above. After
that, the data line returns to an idle high state and com-
munication on the bus can resume. The bus master
would normally send a reset pulse to exit the Convert
command. Read data time slots generated after the
strong pull–up has ended but before issuing a reset
pulse should result in all 1’s if the conversion time was
calculated correctly.
With V
CC
power supply the bus master may either send
a reset pulse to exit the Convert command or continu-
ously generate read data time slots. As long as the
DS2450 is busy with conversions the bus master will
read 0’s. After the conversion is completed the bus mas-
ter will receive 1’s instead. Since in a open–drain envi-
ronment a single 0 overwrites multiple 1’s the bus mas-
ter
can
monitor
multiple
simultaneously and immediately knows when the last
one is ready. As in the parasitically powered scenario
the bus master finally has to exit the Convert command
by issuing a rest pulse.
devices
converting
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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(lèi)型:Differential 信噪比:107 dB 接口類(lèi)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(lèi)型:Differential 信噪比:107 dB 接口類(lèi)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(lèi)型:Differential 信噪比:107 dB 接口類(lèi)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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