AD7176－2高速高分辨率模数转换(ADC)解决方案

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发布时间：2015/3/28 9:23:00 来源：

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ADI公司的AD7176-2是适用于低带宽输入信号的高速高精度高分辨率Σ-Δ模数转换器(ADC),每路取样频率50kSPS(设定时间20us),输出数据速率5 SPS到250 kSPS,低速时分辨率增加,主要用在过程控制中的PLC/DCS模块,温度和压力测量,医疗和科学仪表以及色层分析.本文介绍了AD7176-2主要特性,功能框图,典型应用电路,以及评估板EVAL-AD7176-2SDZ主要特性,框图,电路图,材料清单和PCB设计文件图.
The AD7176-2 is a fast settling, highly accurate, high resolution, multiplexed Σ-Δ analog-to-digital converter (ADC) for low band-width input signals. Its inputs can be configured as two fully differential or four pseudo differential inputs via the integrated crosspoint multiplexer. An integrated precision, 2.5 V, low drift (2 ppm/℃), band gap internal reference (with an output reference buffer) adds functionality and reduces the external component count.
The maximum channel scan data rate is 50 kSPS/channel (settling time of 20 μs), resulting in fully settled data with 17 noise free bits. User-selectable output data rates range from 5 SPS to 250 kSPS. The resolution increases at lower speeds.
The AD7176-2 offers three key digital filters. The fast settling sinc5 + sinc1 filter maximizes the channel scan rate. The sinc3 filter maximizes the resolution for single-channel, low speed applications. For 50 Hz and 60 Hz environments, the AD7176-2 specific filter minimizes the settling times or maximizes the rejection of the line frequency. These enhanced filters enable simultaneous 50 Hz and 60 Hz rejection with a 27 SPS output data rate (with a settling time of 36 ms).
System offset and gain errors can be corrected on a per channel basis. This per channel configurability extends to the output data rate used for each channel when using a sinc5 + sinc1 filter. All switching of the crosspoint multiplexer is controlled by the ADC and can be configured to automatically control an external multiplexer via the GPIO pins.
The specified operating temperature range is −40℃ to +105℃. The AD7176-2 is housed in a 24-lead TSSOP package.

AD7176-2主要特性:
Fast and flexible output rate—5 SPS to 250 kSPS
Fast settling time—20 μs
Channel scan data rate of 50 kSPS/channel
Performance specifications
17 noise free bits at 250 kSPS
20 noise free bits at 2.5 kSPS
22 noise free bits at 5 SPS
INL ±2.5 ppm of FSR
85 dB rejection of 50 Hz and 60 Hz with 50 ms settling
User-configurable input channels
2 fully differential or 4 pseudo differential
Crosspoint multiplexer
On-chip 2.5 V reference (drift 2 ppm/℃)
Internal oscillator, external crystal, or external clock
Power supply
Single supply: 5 V AVDD1,2 V to 5 V AVDD2 and IOVDD
Optional split supply: AVDD1 and AVSS ± 2.5 V
Current: 7.8 mA
Temperature range: −40℃ to +105℃
3- or 4-wire serial digital interface (Schmitt trigger on SCLK)
CRC error checking
SPI, QSPI, MICROWIRE, and DSP compatible
AD7176-2应用:
Process control: PLC/DCS modules
Temperature and pressure measurement
Medical and scientific multichannel instrumentation
Chromatography

图1. AD7176-2功能框图

图2. AD7176-2典型应用电路

评估板EVAL-AD7176-2SDZ
The EVAL-AD7176-2SDZ evaluation kit features the AD7176-2 24-bit, 250 kSPS analog-to-digital converter (ADC). A 7 V to 9 V external bench top supply is regulated to 5 V and 3.3 V to supply the AD7176-2 and support all necessary components. The EVAL-AD7176-2SDZ board connects to the USB port of the PC by connection to the EVAL-SDP-CB1Z motherboard.
The EVAL-AD7176-2SDZ software fully configures the AD7176-2 device register functionality and provides dc time domain analysis in the form of waveform graphs, histograms, and associated noise analysis for ADC performance evaluation.
The EVAL-AD7176-2SDZ is an evaluation board that is designed to allow the user to evaluate the features of the ADC. The user PC software executable controls the AD7176-2 over the USB through the system demonstration platform board (EVAL-SDP-CB1Z).

评估板EVAL-AD7176-2SDZ主要特性:
Full featured evaluation board for the AD7176-2
PC control in conjunction with the system demonstration platform (EVAL-SDP-CB1Z)
PC software for control and data analysis (time domain)
Standalone capability
ONLINE RESOURCES
Evaluation Kit Contents
EVAL-AD7176-2SDZ evaluation board
Evaluation software CD for the AD7176-2
Documents Needed
AD7176-2 data sheet
EVAL-AD7176-2SDZ (UG-478) user guide
Required Software
EVAL-AD7176-2SDZ evaluation software
EQUIPMENT NEEDED
EVAL-AD7176-2SDZ evaluation board
EVAL-SDP-CB1Z system demonstration platform
External 7 V to 9 V power supply
DC signal source
USB cable
PC running Windows with USB 2.0 port