原标题：Microchip MCP3914 3V八路模拟前端(AFE)解决方案

　　Microchip公司的MCP3914是3V八路模拟前端(AFE),包括8个同步取样的Delta-Sigma模数转换器(ADC),8个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校准寄存器以及高速20MHz SPI兼容的串口,主要用在多相电表,电表和能量管理,汽车,手持仪表,医疗和电源监视,音频/视频识别.本文介绍了MCP3914主要特性,功能框图, 以及MCP3914 ADC评估板主要特性, PIM模块和MCP3914数字连接图,电路图,材料清单和PCB与元件布局图.

　　The MCP3914 is a 3V eight-channel Analog Front End (AFE), containing eight synchronous sampling delta-sigma, Analog-to-Digital Converters (ADC), eight 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 MCP3914 ADCs are fully configurable, with features such as: 16/24-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 MCP3914 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 MCP3914 is capable of interfacing with a variety of voltage and current sensors, including shunts, current transformers, Rogowski coils and Hall-effect sensors.

　　MCP3914主要特性:

　　• Eight Synchronous Sampling 24-bit Resolution Delta-Sigma Analog-to-Digital (A/D) Converters

　　• 94.5 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/℃

　　• Differential Voltage Reference Input Pins

　　• High Gain Programmable-Gain Amplifier (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 Serial Peripheral Interface (SPI) 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 40-lead UQFN Package

　　• Extended Temperature Range: -40℃ to +125℃

　　MCP3914应用:

　　• Polyphase Energy Meters

　　• Energy Metering and Power Measurement

　　• Automotive

　　• Portable Instrumentation

　　• Medical and Power Monitoring

　　• Audio/Voice Recognition

　　图1. MCP3914功能框图

　　图2. MCP3914应用框图

　　MCP3914 ADC评估板

　　The MCP3914 ADC Evaluation Board for 16-Bit MCUs system provides the opportunity to evaluate the performance of the MCP3914 eight-channel AFE. It also provides a development platform for 16-bit PIC® device-based applications, using existing 100-pin PIC microcontroller Plug-in Module (PIM) systems that are compatible with the Explorer 16 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 MCP3914 ADC Evaluation Board for 16-Bit MCUs uses the Energy Management Utility software for evaluation of the MCP3914 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.

　　MCP3914 ADC评估板主要特性:

　　• Eight-channel ADC MCP3914 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 MCP3914.

　　• 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 MCP3914 device; includes separate power supplies and power planes on a 4-layer board.

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

　　图3.MCP3914 ADC评估板外形图

　　图4.PIM模块和MCP3914数字连接图

　　MCP3914 ADC评估板材料清单: