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当前位置：首页 -> 方案设计 |
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| MAX11270 24位Delta－Sigma ADC测量参考设计 |
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| 文章来源： 更新时间：2015/4/17 11:01:00 |
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Maxim公司的MAX11270是 24位Delta-Sigma ADC,具有极好的130dB SNR和超低10mW功耗,提供6.5nV/√Hz噪音可编增益放大器,增益设定在1和128之间,主要用在科学仪器,高精度手持传感器,医疗设备和自动测试设备(ATE).本文介绍了MAX11270主要特性和优势,框图和应用框图,以及评估板MAXREFDES75#主要特性,框图,电路图,材料清单和PCB设计图.
The MAX11270 is a 24-bit delta-sigma ADC that achieves excellent 130dB SNR while dissipating an ultra-low 10mW. Sample rates up to 64ksps allow both precision DC and AC measurements. Integral nonlinearity is guaranteed to 4ppm maximum. The THD is -122dB. The MAX11270 communicates via an SPI-compatible serial interface and is available in a small 24-pin TSSOP package.
The MAX11270 offers a 6.5nV/√Hz noise programmable gain amplifier with gain settings between 1x to 128x. Optional buffers are also included to provide isolation of the signal inputs from the switched capacitor sampling network. This allows the MAX11270 to be used with high-impedance sources without compromising available dynamic range.
The MAX11270 operates from a single 2.7V to 3.6V analog supply, or split ±1.8V analog supplies, allowing the analog input to be sampled below ground. The digital supply range is 2.0V to 3.6V, allowing communication with 2.5V, 3V, or 3.3V logic.
MAX11270主要特性和优势:
High Resolution for Instrumentation Applications that Require a Wide Dynamic Range∙ 130dB SNR at 1.9sps∙ 112dB SNR at 1000sps∙ 20.4-Bit Noise-Free Resolution at 1.9sps∙ 17.4-Bit Noise-Free Resolution at 1000sps
Longer Battery Life for Portable Applications∙ 2.4mA Operating Mode Current∙ 4.4mA PGA Low-Noise Mode Current∙ 1μA Sleep Current
High Accuracy for DC Measurements∙ 1ppm INL (typ), 4ppm (max)
Single or Split Analog Supplies Provide Input Voltage Range Flexibility∙ 2.7V to 3.6V (Single Supply) or ±1.8V (Split Supplies)
Flexible High-Performance Filter Architecture Simplifies Design∙ Programmable SINC Filter
Enables System Integration∙ Low-Noise PGA with Gains of 1, 2, 4, 8, 16, 32, 64, 128∙ Signal Buffer Optional∙ 3 General-Purpose I/Os
Enables Integrated Part and System Calibration for Gain and Offset
Robust 24-Pin TSSOP Packaging
MAX11270应用:
Scientific Instrumentation
High-Precision Portable Sensors
Medical Equipment
ATE
图1.MAX11270功能框图
图2.MAX11270应用框图
评估板MAXREFDES75#
Weigh scales perform the critical function of mass measurement for a wide variety of industrial applications. From ultra-small reactant amounts to large cargo containers, weighing provides key information in an array of processes from chemical reactions to commodity management. The critical component of any modern weigh scale is the analog-to-digital converter. The MAXREFDES75# brings a full 24-bit ADC into a high-performance system performing small-signal (down to ±25mV full scale) 24-bit measurements, while generating the high-voltage sensor supply, and producing a 0 to 10V output proportional to the input signal.
The MAXREFDES75# is equipped with multiple sensor-supply options. Either 10V or 3.3V may be used to excite the load cell. Excitation at 10V will provide the highest performance, however, it will require additional components, and hence increase cost, in any final design. The 3.3V rail is required for ADC operation so it will be available in all configurations. Furthermore, the ADC may be configured to operate in a ratiometric mode, with the reference-derived resistor-divider from the 10V rail, or from the MAX6126 voltage reference. The ratiometric method is generally preferred, however, the voltage reference provides the user flexibility to evaluate the system without the changes in gain contributed by the system.
The MAXREFDES75# board receives power from a single DC source of 9V to 40V, 200mA through the X2 terminal block. The MAX17501 generates a +8V rail from the variable input supply. The MAX16910 LDO generates 3.3V for the MAXQ622 from the 8V rail. The MAX13256 generates isolated positive and isolated negative rails for the ADC, DAC, voltage reference, load cell, and analog output. The MAX16910 LDO generates VDD for the MAX542. The MAX8510 LDOs generate AVDD and DVDD for the MAX11270. The MAX9633 generates a low-noise 10V supply for the load cell.
评估板MAXREFDES75#主要特性:
Ratiometric measurement or measurement compared to a precision voltage reference
User-programmable offset and gain calibration for sensor (load cell)
User-programmable offset and gain calibration for DAC
User-programmable voltage output range mapping
MAXREFDES75# System Board
图3.评估板MAXREFDES75#外形图
图4.评估板MAXREFDES75#框图
图4.评估板MAXREFDES75#电路图(1)
图5.评估板MAXREFDES75#电路图(2)
图6.评估板MAXREFDES75#电路图(3)
评估板MAXREFDES75#材料清单:
图7.评估板MAXREFDES75#PCB设计图(1)
图8.评估板MAXREFDES75# PCB设计图(2)
图9.评估板MAXREFDES75# PCB设计图(3)
图10.评估板MAXREFDES75# PCB设计图(4)
图11.评估板MAXREFDES75# PCB设计图(5)
图12.评估板MAXREFDES75# PCB设计图(6)
图13.评估板MAXREFDES75# PCB设计图(7)
图14.评估板MAXREFDES75# PCB设计图(8) |
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