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參數(shù)資料
| 型號： | ALD500RA-10PE |
| 廠商： | Advanced Linear Devices, Inc. |
| 英文描述： | PRECISION INTEGRATING ANALOG PROCESSOR WITH PRECISION VOLTAGE REFERENCE |
| 中文描述： | 精密集成了模擬處理器，高精度電壓基準 |
| 文件頁數(shù)： | 2/12頁 |
| 文件大?。?/td> | 93K |
| 代理商： | ALD500RA-10PE |
2
Advanced Linear Devices
ALD500RAU/ALD500RA/ALD500R
GENERAL THEORY OF OPERATION
Dual-Slope Conversion Principles of Operation
The basic principle of dual-slope integrating analog to digital
converter is simple and straightforward. A capacitor, C
INT
, is
charged with the integrator from a starting voltage, V
X
, for a
fixed period of time at a rate determined by the value of an
unknown input voltage, which is the subject of measurement.
Then the capacitor is discharged at a fixed rate, based on an
external reference voltage, back to V
X
where the discharge
time, or deintegration time, is measured precisely. Both the
integration time and deintegration time are measured by a
digital counter controlled by a crystal oscillator. It can be
demonstrated that the unknown input voltage is determined
by the ratio of the deintegration time and integration time, and
is directly proportional to the magnitude of the external reference
voltage.
The major advantages of a dual-slope converter are:
a. Accuracy is not dependent on absolute values of
integration time t
INT
and deintegration time t
DINT
, but is
dependent on their relative ratios. Long-term clock frequency
variations will not affect the accuracy. A standard crystal
controlled clock running digital counters is adequate to generate
very high accuracies.
b. Accuracy is not dependent on the absolute values of
R
INT and
C
INT
, as long as the component values do not vary
through a conversion cycle, which typically lasts less than 1
second.
c. Offset voltage values of the analog components, such
as V
X
, are cancelled out and do not affect accuracy.
d. Accuracy of the system depends mainly on the accuracy
and the stability of the voltage reference value.
FIGURE 1. ALD500R Functional Block Diagram
GENERAL DESCRIPTION
The ALD500RAU/ALD500RA/ALD500R are integrating
dual slope analog processors, designed to operate on
±
5V
power supplies for building precision analog-to-digital
converters. The ALD500RAU/ALD500RA/ALD500R
feature specifications suitable for 18 bit/17 bit/16 bit
resolution conversion, respectively. Together with three
capacitors, two resistors, and a digital controller, a precision
Analog to Digital converter with auto zero can be
implemented. The digital controller can be implemented
by an external microcontroller, under either hardware
(fixed logic) or software control. For ultra high resolution
applications, up to 23 bit conversion can be implemented
with an appropriate digital controller and software.
The ALD500R series of analog processors accept
differential inputs and the external digital controller first
counts the number of pulses at a fixed clock rate that a
capacitor requires to integrate against an unknown analog
input voltage, then counts the number of pulses required
to deintegrate the capacitor against a known internal
reference voltage. This unknown analog voltage can then
be converted by the microcontroller to a digital word, which
is translated into a high resolution number, representing
an accurate reading. This reading, when ratioed against
the reference voltage, yields an accurate, absolute voltage
measurement reading.
The ALD500R analog processors consist of on-chip digital
control circuitry to accept control inputs, integrating buffer
amplifiers, analog switches, and voltage comparators and
a highly accurate, ultra-stable voltage reference. It
functions in four operating modes, or phases, namely auto
zero, integrate, deintegrate, and integrator zero phases.
At the end of a conversion, the comparator output goes
from high to low when the integrator crosses zero during
deintegration. ALD500R analog processors also provide
direct logic interface to CMOS logic families.
SW-
R
N/C
-
+
+
+
-
+
-
(2)
(17)
(18)
C
OUT
DGND
Level
Shift
Polarity
Detection
Phase
Decoding
Logic
Comp2
Comp1
Integrator
Buffer
REF
Control
Bias
Analog
Switch
Control
Signals
Control Logic
C
S
(20)
A
(15)
B
(16)
AGND
(6)
(13)
(14)
(8)
(12)
(11)
(7)
(3) (19) (10) (9)
(1)
I
B
N/C
V
V
C
INT
C
INT
R
INT
C
AZ
C
AZ
(4)
C-
REF
SW
AZ
SW
S
SW
R
SW
R
C
REF
SW
Az
SW
IN
SW
G
SW
IN
C+
REF
V+
REF
V-
SW-
R
SW+
R
SW+
R
V-
IN
V+
IN
BUF
REF
INT
R
= 100K
CB = 0.1
μ
F
R
REF
C
B
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ALD500RAU-20QEI | PRECISION INTEGRATING ANALOG PROCESSOR WITH PRECISION VOLTAGE REFERENCE |
| ALD500RA-20QEI | PRECISION INTEGRATING ANALOG PROCESSOR WITH PRECISION VOLTAGE REFERENCE |
| ALD500R-50SE | PRECISION INTEGRATING ANALOG PROCESSOR WITH PRECISION VOLTAGE REFERENCE |
| ALD500R-50QE | PRECISION INTEGRATING ANALOG PROCESSOR WITH PRECISION VOLTAGE REFERENCE |
| ALD500R-50PE | PRECISION INTEGRATING ANALOG PROCESSOR WITH PRECISION VOLTAGE REFERENCE |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ALD500RA-10PEL | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 17 Bt A/D w10 ppm VR 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 |
| ALD500RA-10QE | 制造商:ALD 制造商全稱:Advanced Linear Devices 功能描述:PRECISION INTEGRATING ANALOG PROCESSOR WITH PRECISION VOLTAGE REFERENCE |
| ALD500RA-10QEL | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 17 Bit A/D w10ppm VR 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 |
| ALD500RA-10SE | 制造商:ALD 制造商全稱:Advanced Linear Devices 功能描述:PRECISION INTEGRATING ANALOG PROCESSOR WITH PRECISION VOLTAGE REFERENCE |
| ALD500RA-10SEL | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 17 Bt A/D w10 ppm VR 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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