原标题：Microchip MCP3919三路ADC模拟前端(AFE)解决方案

　　Microchip公司的MCP3919是三路模拟前端(AFE),包括三路同步取样Delta-Sigma模数转换器(ADC),三路PGA,相位延迟补偿区块,低漂移基准电压,数字失调和增益误差效准寄存器以及高速20MHz SPI兼容串口.ADC具有16/24位分辨率,32-4096过取样比率(OSR),增益1x-32x,单独关断和重起,抖动和自动调零.主要用在多相电表,能量测量,汽车电子,手持仪表,音频/视频识别以及医疗和电源监测.本文介绍MCP3919主要特性,框图和应用电路,以及用于16位MCU的MCP3919 ADC评估板特性亮点,电路图,材料清单和PCB设计图.

　　The MCP3919 is a 3V three-channel Analog Front End (AFE) containing three synchronous sampling delta-sigma Analog-to-Digital Converters (ADC), three PGAs, phase delay compensation block, low-drift internal voltage reference, digital offset and gain error calibration registers and high-speed 20 MHz SPI-compatible serial interface.

　　The MCP3919 ADCs are fully configurable with features such as: -32x16/24-bit resolution, Oversampling Ratio (OSR) from 32 to 4096, gain from 1x to 32x, independent Shutdown and Reset, dithering and autozeroing.

　　The communication is largely simplified with 8-bit commands including various continuous read/write modes and 16/24/32-bit data formats that can be accessed by the Direct Memory Access (DMA) of an 8/16- or 32-bit MCU and with the separate data ready pin that can directly be connected to an Interrupt Request (IRQ) input of an MCU.

　　The MCP3919 includes advanced security features to secure the communications and the configuration settings such as a CRC-16 checksum on both serial data outputs and static register map configuration. It also includes a register-map lock through an 8-bit secure key to stop unwanted write commands from processing.

　　The MCP3919 is capable of interfacing with a variety of voltage and current sensors, including shunts, current transformers, Rogowski coils and Hall-effect sensors.

　　MCP3919主要特性:

　　• Three Synchronous Sampling 24-bit Resolution Delta-Sigma A/D Converters

　　• 93.5 dB SINAD, -107 dBc Total Harmonic Distortion (THD) (up to 35th Harmonic), 112 dBFS SFDR for Each Channel

　　• Enables 0.1% Typical Active Power Measurement Error over a 10,000:1 Dynamic Range

　　• Advanced Security Features:

　　- 16-bit Cyclic Redundancy Check (CRC) Checksum on All Communications for Secure Data Transfers

　　- 16-bit CRC Checksum and Interrupt Alert for Register Map Configuration

　　- Register Map Lock with 8-bit Secure Key

　　• 2.7V-3.6V AVDD, DVDD

　　• Programmable Data Rate up to 125 ksps:

　　- 4 MHz Maximum Sampling frequency

　　- 16 MHz Maximum Master Clock

　　• Oversampling Ratio up to 4096

　　• Ultra-Low Power Shutdown Mode with < 10 μA

　　• -122 dB Crosstalk between Channels

　　• Low Drift 1.2V Internal Voltage Reference: 9 ppm/°C

　　• Differential Voltage Reference Input Pins

　　• High Gain PGA on Each Channel (up to 32 V/V)

　　• Phase Delay Compensation with 1 μs Time Resolution

　　• Separate Data Ready Pin for Easy Synchronization

　　• Individual 24-bit Digital Offset and Gain Error

　　Correction for Each Channel

　　• High-Speed 20 MHz SPI Interface with Mode 0,0 and 1,1 Compatibility

　　• Continuous Read/Write Modes for Minimum Communication Time with Dedicated 16/32-bit Modes

　　• Available in a 28-lead 5 x 5 mm QFN and 28-lead SSOP Packages

　　• Extended Temperature Range: -40°C to +125°C

　　MCP3919应用:

　　• Polyphase Energy Meters

　　• Energy Metering and Power Measurement

　　• Automotive

　　• Portable Instrumentation

　　• Medical and Power Monitoring

　　• Audio/Voice Recognition

　　图1. MCP3919框图

　　图2. MCP3919应用案例电路图

　　MCP3919 ADC评估板

　　The MCP3919 ADC Evaluation Board for 16-Bit MCUs system provides the opportunity to evaluate the performance of the MCP3919 three-channel Analog Front End (AFE).

　　It also provides a development platform for 16-bit microcontroller-based applications, using the existing 100-pin PIC® microcontroller Plug-in Module (PIM) systems that are compatible with the Explorer 16 Evaluation Board (DM240001) and other high pin count PIC device based demo boards. The system comes with a programmed PIC24FJ256GA110 PIM module that communicates with the Energy Management Utility software for data exchange and ADC setup.

　　The MCP3919 ADC Evaluation Board for 16-Bit MCUs uses the Energy Management Utility software for evaluation of the MCP3919 via a USB connection to the board. A download link for this software can be found on the evaluation board’s web page. For instructions on the use of this software, refer to the supporting documentation included within the application install package.

　　用于16位MCU的MCP3919 ADC评估板特性亮点:

　　• Three-channel ADC MCP3919 output display using serial communication to the

　　PC software interface.

　　• Simultaneous 57 ksps at OSR32 address loop ALL or 95 dB SINAD at OSR512

　　performance on MCP3919.

　　• System and ADC performance analysis through graphical PC tools showing noise

　　histogram, frequency domain (FFT), time domain scope plot and statistical numerical analysis.

　　• Robust hardware design with analog grounding and analog/digital separation, allowing low noise evaluation of the MCP3919 device; includes separate power supplies and power planes on a four-layer board.

　　• PICtail™ Plus connectors for Explorer 16 daughter board compatibility.

　　图3. MCP3919 ADC评估板外形图

　　16位MCU MCP3919 ADC评估板包括:

　　• MCP3919 ADC Evaluation Board for 16-Bit MCUs (Part number ADM00573)

　　• PIC24FJ256GA110 PIM

　　• USB Cable

　　• Important Information Sheet

　　图4. PIM/MCP3919 ADC数字连接框图

　　MCP3919 ADC评估板材料清单(BOM):