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參數(shù)資料
| 型號(hào)： | MCP3204-BIP |
| 廠商： | Microchip Technology Inc. |
| 英文描述： | CBS SCREW-MOUNT NYLON 3/4,1 |
| 中文描述： | 2.7 4-Channel/8-Channel 12位A / D轉(zhuǎn)換器具有SPI串行接口 |
| 文件頁數(shù)： | 17/20頁 |
| 文件大?。?/td> | 425K |
| 代理商： | MCP3204-BIP |
1999 Microchip Technology Inc.
Preliminary
DS21298B-page 17
MCP3204/3208
6.2
Maintaining Minimum Clock Speed
When the MCP3204/3208 initiates the sample period,
charge is stored on the sample capacitor. When the
sample period is complete, the device converts one bit
for each clock that is received. It is important for the
user to note that a slow clock rate will allow charge to
bleed off the sample capacitor while the conversion is
taking place. At 85°C (worst case condition), the part
will maintain proper charge on the sample capacitor for
at least 1.2ms after the sample period has ended. This
means that the time between the end of the sample
period and the time that all 12 data bits have been
clocked out must not exceed 1.2ms (effective clock fre-
quency of 10kHz). Failure to meet this criterion may
induce linearity errors into the conversion outside the
rated specifications. It should be noted that during the
entire conversion cycle, the A/D Converter does not
require a constant clock speed or duty cycle, as long as
all timing specifications are met.
6.3
Buffering/Filtering the Analog Inputs
If the signal source for the A/D Converter is not a low
impedance source, it will have to be buffered or inaccu-
rate conversion results may occur. See Figure 4-2. It is
also recommended that a filter be used to eliminate any
signals that may be aliased back in to the conversion
results. This is illustrated in Figure 6-3 where an op
amp is used to drive the analog input of the
MCP3204/3208. This amplifier provides a low imped-
ance source for the converter input and a low pass fil-
ter, which eliminates unwanted high frequency noise.
Low pass (anti-aliasing) filters can be designed using
Microchip’s free interactive
FilterLab
software.
Fil-
terLab
will calculate capacitor and resistors values, as
well as determine the number of poles that are required
for the application. For more information on filtering sig-
nals, see the application note AN699
“Anti-Aliasing
Analog Filters for Data Acquisition Systems.”
FIGURE 6-3:
used to implement a 2nd order anti-aliasing filter for
the signal being converted by the MCP3204.
The MCP601 Operational Amplifier is
6.4
Layout Considerations
When laying out a printed circuit board for use with ana-
log components, care should be taken to reduce noise
wherever possible. A bypass capacitor should always
be used with this device and should be placed as close
as possible to the device pin. A bypass capacitor value
o
f 1μF is recommended.
Digital and analog traces should be separated as much
as possible on the board and no traces should run
underneath the device or the bypass capacitor. Extra
precautions should be taken to keep traces with high
frequency signals (such as clock lines) as far as possi-
ble from analog traces.
Use of an analog ground plane is recommended in
order to keep the ground potential the same for all
devices on the board. Providing V
connections to
devices in a “star” configuration can also reduce noise
by eliminating return current paths and associated
errors. See Figure 6-4. For more information on layout
tips when using A/D Converters, refer to AN688 “Lay-
out Tips for 12-Bit A/D Converter Applications”
.
FIGURE 6-4:
configuration in order to reduce errors caused by
current return paths.
V
traces arranged in a ‘Star’
FilterLab is a trademark of Microchip Technology Inc. in
the U.S.A and other countries. All rights reserved.
MCP3204
V
DD
10
μF
IN-
IN+
-
+
V
IN
C
1
C
2
V
REF
4.096V
Reference
0.1μF
ADI
REF198
1μF
1μF
0.1μF
MCP601
R
1
R
2
R
3
R
4
V
Connection
Device 1
Device 2
Device 3
Device 4
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MCP3204-BISL | 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:2.7V 4-Channel/8-Channel 12-Bit A/D Converters with SPI Serial Interface |
| MCP3204-BIST | 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:2.7V 4-Channel/8-Channel 12-Bit A/D Converters with SPI Serial Interface |
| MCP3204-CI/P | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-bit SPI 4 Chl 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 |
| MCP3204-CI/P | 制造商:Microchip Technology Inc 功能描述:IC 12BIT ADC 3204 DIP14 |
| MCP3204-CI/SL | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-bit SPI 4 Chl 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 |
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