Microchip公司的MCP3903是業界首個用于三相電表的六路模擬前端(AFE),包括三對兩個帶PGA同步取樣Delta-Sigma的16/24位ADC,相位延遲補償區塊,基準電壓以及SPI兼容的高速10MHz串行接口.轉換器中的抖動算法能降低閑音(idle tones),改善THD,SINAD為91dB,THD為-100dBc,SFDR為102dB,可編程數據速率高達64ksps,關斷模式功耗小于2uA,任意兩路間串擾為-115dB,內部基準電源的溫票為5 ppm/°C,主要用在電表和能量測量,手提儀表以及醫療和電源監視等.本文介紹了MCP3903主要特性,功能方框圖以及用于16位MCU的MCP3903 ADC評估板亮點,電路圖和材料清單與PCB元件布局圖.

Microchips First Six-Channel Analog Front End for Three-Phase Energy Metering Offers Industry-Leading Accuracy Microchip

The MCP3903 is a six-channel Analog Front End (AFE) containing three pairs made out of two synchronous sampling Delta-Sigma Analog-to-Digital Converters (ADC) with PGA, a phase delay compensation block, internal voltage reference, and high-speed 10 MHz SPI compatible serial interface. The converters contain a proprietary dithering algorithm for reduced idle tones and improved THD.

The internal register map contains 24-bit wide ADC data words, a modulator output register as well as six 24-bit writable control registers to program gain, over-sampling ratio, phase, resolution, dithering, shut-down, reset and several communication features.

The communication is largely simplified with various Continuous Read modes that can be accessed by the Direct Memory Access (DMA) of an MCU and with separate Data Ready pins that can directly be connected to the Interrupt Request (IRQ) input of an MCU. The MCP3903 is capable of interfacing to a large variety of voltage and current sensors including shunts, current transformers, Rogowski coils, and Hall-effect Sensors.

MCP3903主要特性:

• Six Synchronous Sampling 16/24-bit Resolution Delta-Sigma A/D Converters with Proprietary Multi-Bit Architecture

• 91 dB SINAD, -100 dBc Total Harmonic Distortion (THD) (up to 35th harmonic), 102 dB Spurious-free Dynamic Range (SFDR) for Each Channel

• Programmable Data Rate up to 64 ksps

• Ultra Low-Power Shutdown Mode with <2 μA

• -115 dB Crosstalk Between any Two Channels

• Low Drift Internal Voltage Reference: 5 ppm/°C
• Differential Voltage Reference Input Pins

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

• Phase Delay Compensation Between Each Pair of Channels with 1 μs Time Resolution

• High-Speed Addressable 10 MHz SPI Interface with Mode 0,0 and 1,1 Compatibility

• Independent Analog and Digital Power Supplies 4.5V - 5.5V AVDD, 2.7V - 3.6V DVDD

• Available in Small 28-lead SSOP Package

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

MCP3903應用:

• Energy Metering and Power Measurement

• Portable Instrumentation

• Medical and Power Monitoring

圖1.MCP3903功能方框圖

用于16位MCU的MCP3903 ADC評估板

The MCP3903 ADC Evaluation Board for 16-Bit MCUs system lets users evaluate the performance of the MCP3903 six-channel ADC. It also provides a development platform for 16-bit PIC® MCU-based applications, using existing 100-pin PIM systems, compatible with the Explorer-16 and other high pincount PIC demo boards. The system comes with programmed PIC24FJ128GA010 PIM modules that communicate with the LabView GUI for data exchange and ADC setup.

MCP3903 ADC評估板亮點:

• Six-channel ADC MCP3903 output display using serial communication to the PC Software Interface and LCD

• Simultaneous 4 ksps at 91 dB Signal-to-Noise and Distortion Ratio (SINAD) performance. The ADC can run up to 64 ksps.

• System and ADC performance analysis through graphical PC tools showing Time domain scope plot, Frequency Domain (FFT), and statistical numerical analysis.

• Robust hardware design with analog grounding and analog/digital separation, allowing low noise evaluation of the MCP3903 devices. Separate power supplies and power planes - 4 layer board.

• Pigtail Plus connectors for Explorer-16 daughter board compatibility.

圖2.MCP3903 ADC評估板外形圖

圖3.MCP3903 ADC評估板電路圖(1):模擬

圖4.MCP3903 ADC評估板電路圖(2):LCD和UART

圖5.MCP3903 ADC評估板電路圖(3):USB和存儲器

圖6.MCP3903 ADC評估板電路圖(4):MCU

圖7.MCP3903 ADC評估板電路圖(4):PIM模塊

圖8.MCP3903 ADC評估板電路圖(5):電源

圖9.MCP3903 ADC評估板元件布局圖:正面

圖10.MCP3903 ADC評估板元件布局圖:背面
MCP3903 ADC評估板材料清單:



詳情請見:
http://ww1.microchip.com/downloads/en/DeviceDoc/25048B.pdf
和
http://ww1.microchip.com/downloads/en/DeviceDoc/51994A.pdf