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參數(shù)資料
| 型號： | ADCV0831 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | 8 Bit Serial I/O Low Voltage Low Power ADC with Auto Shutdown in a SOT Package(SOT封裝8位串行輸入/輸出低壓低功耗帶自動(dòng)關(guān)閉功能的A/D轉(zhuǎn)換器) |
| 中文描述： | 8位采用SOT封裝串行I / ?具有自動(dòng)關(guān)機(jī)低電壓低功耗ADC（采用SOT封裝8位串行輸入/輸出低壓低功耗帶自動(dòng)關(guān)閉功能的的A / D轉(zhuǎn)換器） |
| 文件頁數(shù)： | 6/9頁 |
| 文件大?。?/td> | 180K |
| 代理商： | ADCV0831 |
Functional Description
The design of this converter utilizes a comparator structure
with built-in sample-and-hold which provides for V
IN
to be
converted by a successive approximation routine.
The analog input voltage can range from 50mV below
ground to 50mV above V
CC
without degrading conversion
accuracy.
The ADCV0831 is intended to work with a CPU which
strobes data on the clock’s rising edge. The ADCV0831
strobes data on the clock’s falling edge so that the data out-
put is stable when the CPU reads it in.
When the Chip Select pin is high, the output is TRI-STATE
and the ADCV0831 is in shutdown mode and draws less
than 30 μA of current. During shutdown the digital logic
draws no current at CMOS logic levels, and the analog cir-
cuitry is turned off. When the Chip Select pin goes low, all the
analog circuitry turns on, and the conversion process begins.
1.0 THE DIGITAL INTERFACE
The most important characteristic of this converter is the se-
rial data link with the controlling processor. Using a serial
communication format offers three very significant system
improvements. It allows many functions to be included in a
small package, it can eliminate the transmission of low level
analog signals by locating the converter right at the analog
sensor, and can transmit highly noise immune digital data
back to the host processor.
To understand the operation of this converter it is best to re-
fer to the Timing Diagrams and to follow a complete conver-
sion sequence.
1.
A conversion is initiated by pulling the CS (chip select)
line low. This line must be held low for the entire conver-
sion.
2.
During the conversion the output of the SAR comparator
indicates whether the analog input is greater than (high)
or less than (low) a series of successive voltages in a re-
sistor ladder (last 8 bits). After each comparison the
comparator’s output is shifted to the DO line on the fall-
ing edge of CLK. This data is the result of the conversion
being shifted out (with the MSB first) and can be read by
the processor immediately.
3.
After 11 clock periods the conversion is completed.
4.
All internal registers are cleared when the CS line is
high. See Data Input Timing under Timing Diagrams. If
another conversion is desired CS must make a high to
low transition.
2.0 REFERENCE CONSIDERATIONS
In a ratiometric system, the analog input voltage is propor-
tional to the voltage used for the A/D reference. This voltage
is the system power supply. This technique relaxes the sta-
bility requirements of the system reference as the analog in-
put and A/D reference move together maintaining the same
output code for a given input condition.
Since there is no separate reference and analog supply pins,
the analog side is very sensitive. The PC layout of the
ADCV0831 is very critical. The ADCV0831 should be used
with an analog ground plane and single-point grounding
techniques. The Gnd pin should be tied directly to the ground
plane. One supply bypass capacitor (0.1 μF) is recom-
mended to decouple all the digital signals on the supplies.
The lead length of the capacitor should be as short as pos-
sible.
3.0 THE ANALOG INPUT
The most important feature of this converter is that it can be
located right at the analog signal source through just a few
wires. It can communicate with a processor with a highly
noise immune serial bit stream. This greatly minimizes cir-
cuitry to maintain analog signal accuracy which otherwise is
most susceptible to noise pickup. However, a few words are
in order with regard to the analog inputs should the input be
noisy
to
begin
with
or
possibly
common-mode voltage.
The input has a sample and hold, therefore a capacitor (0.01
μF) is needed at the input pin in order to swamp out any
feedthrough signal coming from the sample and hold cir-
cuitry.
The input capacitor lead length is not as critical as the supply
decoupling capacitor, as long as the capacitor is large
enough to swamp out any sample and hold feedthrough.
Source resistance limitation is important with regard to the
DC leakage currents of the input multiplexer. Bypass capaci-
tors should not be used if the source resistance is greater
than 1k
. The worst-case leakage current of
±
1μAover tem-
perature will create a 1mV input error with a 1k
source re-
sistance. An op-amp RC active low pass filter can provide
both impedance buffering and noise filtering should a high
impedance signal source be required.
riding
on
a
large
DS100104-59
Recommended Power Supply Bypassing
A
www.national.com
6
相關(guān)PDF資料 |
PDF描述 |
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| ADCV0831M6 | 8 Bit Serial I/O Low Voltage Low Power ADC with Auto Shutdown in a SOT Package |
| ADCV0831M6X | 8 Bit Serial I/O Low Voltage Low Power ADC with Auto Shutdown in a SOT Package |
| ADCV08832 | Low Voltage, 8-Bit Serial I/O CMOS A/D Converter with Sample/Hold Function |
| ADCV08832CIMX | Low Voltage, 8-Bit Serial I/O CMOS A/D Converter with Sample/Hold Function |
| ADCV08832CIM | Low Voltage, 8-Bit Serial I/O CMOS A/D Converter with Sample/Hold Function |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADCV0831B WAF | 制造商:Texas Instruments 功能描述: |
| ADCV0831EVAL | 功能描述:BOARD EVALUATION FOR ADCV0831 RoHS:是 類別:編程器，開發(fā)系統(tǒng) >> 評估板 - 模數(shù)轉(zhuǎn)換器 (ADC) 系列:- 產(chǎn)品培訓(xùn)模塊:Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:1 系列:- ADC 的數(shù)量:1 位數(shù):12 采樣率（每秒）:94.4k 數(shù)據(jù)接口:USB 輸入范圍:±VREF/2 在以下條件下的電源（標(biāo)準(zhǔn)）:- 工作溫度:-40°C ~ 85°C 已用 IC / 零件:MAX11645 已供物品:板，軟件 |
| ADCV0831M6 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:8 Bit Serial I/O Low Voltage Low Power ADC with Auto Shutdown in a SOT Package |
| ADCV0831M6X | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:8 Bit Serial I/O Low Voltage Low Power ADC with Auto Shutdown in a SOT Package |
| ADCV08832 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Low Voltage, 8-Bit Serial I/O CMOS A/D Converter with Sample/Hold Function |
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