原标题：Freescale MK30X256 MCU单相电表参考设计

　　freescale公司的Kinetis KM3x MCU是基于低功耗ARM Cortex-M0+核的MCU,专门设计用于单相和三相电表,水表和气表以及其它精密测量应用.器件包括由多个24位Sigma-Delta ADC,可编增益放大器,低温度飘移的基准电压和相移比较器等组成的模拟前端(AFE),以及多种安全特性,主要用在智能电表,水表,气表,倾斜测量,工业流体测量和控制,精密距离测量系统以及网络和测试测量.本文介绍了Kinetis KM3x MCU主要特性,框图,以及单相电表参考设计RDKM3METERING1PH主要特性,框图,电路图,材料清单和PCB元件布局外形图.

　　Kinetis KM3x MCUs are based upon the low-power ARM® Cortex®-M0+ core and are designed for single-chip one-two- and three -phase electricity meters, as well as flow meter and other precision measurement applications. Kinetis KM3x MCUs include a powerful analog front end consisting of multiple 24-bit sigma delta ADCs, programmable gain amplifiers, voltage reference with low drift over temperature and a phase shift compensator. A large range of security features including a memory protection unit, external tamper detection pins, iRTC with tamper detect and a random number generator provide protection of supplier/user data within the MCU and from the MCU to the power grid. A low-power segment LCD controller support up to 288 segments and eight backplanes.

　　MK30X256主要特性:

　　• Operating Characteristics

　　– Voltage range: 1.71 V to 3.6 V (when Analog Front End (AFE) is not used)

　　– Voltage range: 2.7 V to 3.6 V (when Analog Front End (AFE) is used)

　　– iRTC battery supply voltage range: 1.71 to 3.6 V

　　– Flash write voltage range: 1.71 to 3.6 V

　　– Temperature range (ambient): -40℃ to 85℃

　　• Performance

　　– Up to 50 MHz ARM Cortex-M0+ core delivering 0.95 Dhrystone MIPS per MHz

　　• Memories and memory interfaces

　　– 128/64 KB program flash memory. There is no FlexMemory on these devices

　　– 16 KB of single access RAM

　　• Clocks

　　– 1 to 32 MHz crystal oscillator

　　– 32 kHz crystal oscillator

　　– Multi-purpose clock generator

　　• System peripherals

　　– Multiple low-power modes to provide power optimization based on application requirements

　　– Memory protection unit with multi-master protection

　　– 4-channel DMA controller, supporting up to 64 request sources

　　– External watchdog monitor

　　– Robust watchdog monitor

　　– Low-leakage wakeup unit

　　– Asynchronous wakeup unit

　　– Peripheral Crossbar (allows internal signals to be connected to other on-chip modules)

　　• Security and integrity modules

　　– Hardware programmable CRC module to support fast cyclic redundancy checks

　　– Hardware random-number generator

　　– 128-bit unique identification (ID) number per chip

　　• Human-machine interface

　　– Segment LCD controller supporting up to 36 frontplanes and 8 backplanes or 40 frontplanes and 4 backplanes

　　– General-purpose input/output which can acts as

　　Rapid GPIO (single cycle access)

　　• Analog modules

　　– 16-bit SAR ADC

　　– 24-bit Analog Front End comprising of 24-bit Sigma Delta ADCs (after averaging)

　　– Programmable Gain Amplifier (PGA with gains upto 32)

　　– Two analog comparators (CMP) containing a 6-bit DAC and programmable reference input

　　– 1.2V Voltage reference

　　• Timers

　　– 4 channel Quad Timer with 16-bit counters

　　– Periodic interrupt timers

　　– 16-bit low-power timer

　　– Independent Real Time Clock with calendaring and compensation

　　• Communication interfaces

　　– One SPI module with FIFO support (supports 5V AMR operation)

　　– One SPI module without FIFO (no AMR operation)

　　– Two I2C modules with SMBus support

　　– Two UART modules with ISO7816 support and

　　Two UART without ISO 7816 support

　　– Any one SCI can be used for IrDA operation. 5V AMR support on one SCI.

　　MK30X256目标应用:

　　Industrial

　　Gas and Water Meter

　　Phase Measurement Units

　　Tilt Measurement

　　Industrial Flow Measurement and Control

　　Precision Distance Measurement Systems

　　Networking

　　Test and Measurement

　　图1. Kinetis KM3x MCU系列框图

　　RDKM3METERING1PH: Kinetis KM3x MCU单相电表参考设计

　　With the growing consumption of energy worldwide, particularly in the residential market, utility providers need increasingly accurate and cost-effective energy metering solutions. The Kinetis M series single-phase electricity meter reference design addresses these accuracy and cost needs by providing a high-performance analog front end (24- bit AFE) combined with an embedded programmable gain amplifier (PGA) to increase the accuracy of energy measurement, along with a cost-effective shunt sensing circuit implementation and bill of materials (BOM).

　　The single-phase meter reference design is used for measurement and registration of active and reactive energy in single-phase two-wire networks for direct connection. It is pre-certified according to European EN50470- 1, EN50470-3, class B and C, as well as to IEC 62053-21 and IEC 62052-11 international standards for electronic meters of active energy classes 2 and 1.

　　RDKM3METERING1PH主要特性:

　　5 to 80 A current range

　　85 to 264 V, 50/60Hz voltage range

　　Accuracy class: B or C (active energy EN50470-3) and 3 or 2 percent (reactive energy EN62053-23)

　　Line frequency measurement (for precision zero-cross detection)

　　Cost-effective shunt-resistor sensing circuit implementation

　　Low-power modes including the use of built-in RTC (Li-battery backup)

　　4 x 22 segment LCD, including charge pump (values shown on LCD: V, A, W, Var, VA, kWh, kVarh, cos F, Hz, time, date)

　　Single built-in mechanical button as control interface

　　An upper and lower tamper meter cover monitoring with time stamp stored in meter logbook in external NVM (optional)

　　Isolated (4 kV) RS232 port for monitoring, parameterization and firmware upgrade

　　LED pulse outputs (kWh, kVarh)

　　IEC 1107 infrared hardware interface

　　RF connector supporting sub GHz or 2.4 GHz 802.15.4 communications for AMR and remote control (KW0x or KW2x wireless MCU module optional)

　　Low-power, 3-axis Xtrinsic tilt sensor for electronic tamper detection (optional)

　　EMC proven design (EN61000-4-2, EN610004-4)

　　Cost-effective bill of materials (BOM)

　　图2. 单相电表参考设计RDKM3METERING1PH外形图

　　图3. 单相电表参考设计RDKM3METERING1PH硬件框图

　　图4. 单相电表参考设计RDKM3METERING1PH框图

　　单相电表参考设计RDKM3METERING1PH材料清单:

　　图6. 单相电表参考设计RDKM3METERING1PH PCB外形图:顶层

　　图7. 单相电表参考设计RDKM3METERING1PH PCB外形图:底层