概述

　　为了实现铁塔直流电能表测量电压、电流、功率、正向与反向电能的功能，需测量5路直流电流和1路直流电压，需高速的处理器及独立的RTC时钟带备份电池，外接Flash对采集数据进行备份，最后通过RS485总线入网把数据传输给监控平台。

　　本方案针对此需求采用2片计量芯片进行6路采集，采用48MHz高速的EFM8UB20F64G 8位MCU进行数据处理，MCU的双串口分别进行RS-485通讯和PC端通讯，采用EPSON的小体积高性能的RX8130完成RTC的功能，MAXELL的 CR1220电池给RX8130掉电时提供电源。采用Silicon Labs的数字隔离芯片Si8622对RS-485总线进行隔离，瞬态抑制二极管阵列SM712对RS485进行进一步保护，使系统更安全可靠的完成测量功能。

　　器件优势

　　· Silicon Labs 8位MCU EFM8UB20F64G双串口满足RS-485总线和PC端通讯， SPI总线外挂两片计量芯片，EMIF总线满足Flash存储接口需求，IIC总线满足RTC时钟接口需求，48M系统时钟满足快速运算需求。主推型号，高性价比。

　　元件供应型号：EFM8UB20F64G-B-QFP48                 品牌：SILICON LABS

【EFM8UB20】

EFM8UB属于Universal Bee系列MCU，为业界集成度最高、带USB接口的混合信号8位微控制器。EFM8UB2搭载高精度振荡器、时钟恢复电路以及集成收发器，不需要任何外部元件即可用于所有全速USB应用。

产品特色

流水线式8位8051 MCU内核，最大工作频率达48 MHz

兼容无晶振全速/低速USB 2.0的控制器，具有1kB缓冲区

一个单端差分10位ADC和两个模拟比较器

内部48MHz振荡器支持无晶振USB和UART操作，在使用USB时钟恢复时精度为±0.25%

2个UART、1个SPI、2个SMBus/I2C串行通信接口

EFM8UB20框图

EFM8 Universal Bee Family EFM8UB2 Data Sheet

The EFM8UB2, part of the Universal Bee family of MCUs, is a multi-purpose line of 8-bit microcontrollers with USB feature set.

These devices offer high value by integrating a USB peripheral interface with a high precision oscillator, clock recovery circuit, and integrated transceiver, making them ideal for any full speed USB applications with no external components required. With an efficient 8051 core and precision analog, the EFM8UB2 family is also optimal for embedded applications.

EFM8UB2 applications include the following:

• USB I/O controls, dongles

• High-speed communication bridge

• Consumer electronics

• Medical equipment

KEY FEATURES

• Pipelined 8-bit 8051 MCU Core with 48 MHz maximum operating frequency

• Up to 40 multifunction I/O pins

• Crystal-less full speed/low speed USB 2.0 compliant controller with 1 KB buffer memory

• One differential 10-bit ADC and two analog comparators

• Internal 48 MHz oscillator with ±0.25% accuracy with USB clock recovery supports crystal-free USB and UART operation

• 2 UARTs, SPI, 2 SMBus/I2C serial communications

Feature List

The EFM8UB2 highlighted features are listed below.

• Core:

• Pipelined CIP-51 Core

• Fully compatible with standard 8051 instruction set

• 70% of instructions execute in 1-2 clock cycles

• 48 MHz maximum operating frequency

• Memory:

• Up to 64 KB flash memory, in-system re-programmable from firmware.

• Up to 4352 bytes RAM (including 256 bytes standard 8051 RAM and 4096 bytes on-chip XRAM)

• Power:

• Internal LDO regulator for CPU core voltage

• Internal 5-to-3.3 V LDO allows direct connection to USB supply net

• Power-on reset circuit and brownout detectors

• I/O: Up to 40 total multifunction I/O pins:

• Flexible peripheral crossbar for peripheral routing

• 10 mA source, 25 mA sink allows direct drive of LEDs

• Clock Sources:

• Internal 48 MHz precision oscillator ( ±1.5% accuracy without USB clock recovery, ±0.25% accuracy with USB clock recovery)

• Internal 80 kHz low-frequency oscillator

• External crystal, RC, C, and CMOS clock options

• Timers/Counters and PWM:

• 5-channel Programmable Counter Array (PCA) supporting PWM, capture/compare, and frequency output modes with watchdog timer function

• 6 x 16-bit general-purpose timers

• Communications and Digital Peripherals:

• Universal Serial Bus (USB) Function Controller with eight

flexible endpoint pipes, integrated transceiver, and 1 KB

FIFO RAM

• 2 x UART

• SPI™ Master / Slave

• 2 x SMBus™/I2C™ Master / Slave

• External Memory Interface (EMIF)

• Analog:

• 10-Bit Analog-to-Digital Converter (ADC0)

• 2 x Low-current analog comparators

• On-Chip, Non-Intrusive Debugging

• Full memory and register inspection

• Four hardware breakpoints, single-stepping

• Pre-loaded USB bootloader

• Temperature range -40 to 85 ºC

• Single power supply 2.65 to 3.6 V

• QFP48, QFP32, and QFN32 packages

With on-chip power-on reset, voltage supply monitor, watchdog timer, and clock oscillator, the EFM8UB2 devices are truly standalone system-on-a-chip solutions. The flash memory is reprogrammable in-circuit, providing non-volatile data storage and allowing field upgrades of the firmware. The on-chip debugging interface (C2) allows non-intrusive (uses no on-chip resources), full speed, in-circuit debugging using the production MCU installed in the final application. This debug logic supports inspection and modification of memory and registers, setting breakpoints, single stepping, and run and halt commands. All analog and digital peripherals are fully functional while debugging. Each device is specified for 2.65 to 3.6 V operation and is available in 32-pin QFN, 32-pin QFP, or 48-pin QFP packages. All package options are lead-free and RoHS compliant.

　　· Silicon Labs数字隔离芯片Si8622，可达5KVvrms隔离电压，150Mbps高速隔离，满足电力行业3.75KV隔离电压需求， 满足RS-485总线115200bsp 通讯率，保证数据传输的可靠性与安全性。

　　元件供应型号：SI8622EC-B-IS                                    品牌：SILICON LABS

【Si861x/2x Data Sheet】

Low-Power Single and Dual-Channel Digital Isolators Silicon Lab's family of ultra-low-power digital isolators are CMOS devices offering substantial data rate, propagation delay, power, size, reliability, and external BOM advantages over legacy isolation technologies. The operating parameters of these products remain stable across wide temperature ranges and throughout device service life for ease of design and highly uniform performance. All device versions have Schmitt trigger inputs for high noise immunity and only require VDD bypass capacitors.

Data rates up to 150 Mbps are supported, and all devices achieve propagation delays of less than 10 ns. Ordering options include a choice of isolation ratings (2.5, 3.75 and 5 kV) and a selectable fail-safe operating mode to control the default output state during power loss. All products are safety certified by UL, CSA, VDE, and CQC, and products

in wide-body packages support reinforced insulation withstanding up to 5 kVRMS. Automotive Grade is available for certain part numbers. These products are built using

automotive-specific flows at all steps in the manufacturing process to ensure the robustness and low defectivity required for automotive applications.

Industrial Applications

• Industrial automation systems

• Medical electronics

• Isolated switch mode supplies

• Isolated ADC, DAC

• Motor control

• Power inverters

• Communications systems Safety Regulatory Approvals

• UL 1577 recognized

• Up to 5000 VRMS for 1 minute

• CSA component notice 5A approval

• IEC 60950-1, 61010-1, 60601-1 (reinforced insulation)

• VDE certification conformity

SI8622系列

Si8622BB-B-IS

Si8622EB-B-IS

Si8622BC-B-IS

Si8622EC-B-IS

Si8622BD-B-IS

Si8622ED-B-IS

Si8622BT-IS 1

Si8622ET-IS 1

• Si862xxT options certified to reinforced VDE 0884-10

• All other options certified to IEC 60747-5-5 and reinforced 60950-1

• CQC certification approval

• GB4943.1

Automotive Applications

• On-board chargers

• Battery management systems

• Charging stations

• Traction inverters

• Hybrid Electric Vehicles

• Battery Electric Vehicles

KEY FEATURES

• High-speed operation

• DC to 150 Mbps

• No start-up initialization required

• Wide Operating Supply Voltage

• 2.5–5.5 V

• Up to 5000 VRMS isolation

• Reinforced VDE 0884-10, 10 kV surgecapable (Si862xxT)

• 60-year life at rated working voltage

• High electromagnetic immunity

• Ultra low power (typical) 5 V Operation

• 1.6 mA per channel at 1 Mbps

• 5.5 mA per channel at 100 Mbps 2.5 V Operation

• 1.5 mA per channel at 1 Mbps

• 3.5 mA per channel at 100 Mbps

• Schmitt trigger inputs

• Selectable fail-safe mode

• Default high or low output (ordering option)

• Precise timing (typical)

• 10 ns propagation delay

• 1.5 ns pulse width distortion

• 0.5 ns channel-channel skew

• 2 ns propagation delay skew

• 5 ns minimum pulse width

• Transient Immunity 50 kV/µs

• AEC-Q100 qualification

• Wide temperature range

• –40 to 125 °C

• RoHS-compliant packages

• SOIC-16 wide body

• SOIC-8 narrow body

• Automotive-grade OPNs available

• AIAG compliant PPAP documentation support

      • IMDS and CAMDS listing support

Si8622BC-IS 2 通道 1kV 数字隔离器

Silicon Lab 的超低功耗数字隔离器系列是能够提供一到六个通道的 CMOS 设备。可选购适合 I²C 应用的双向功能产品。这些产品的操作参数在广泛的温度范围内保持不变，并贯穿整个设备使用年限，便于设计和高度统一性能。所有设备版本均具有施密特触发器输入，供高抗扰性，且只需要 VDD 旁路电容器。支持最高 150 Mbps 的数据传输率，并且所有设备最多只会产生不足 13 ns 的传输迟延。订购选件时可选择隔离额定值 (2.5、3.75 和 5 kV) 以及可选配的故障保护操作模式，在掉电时控制默认输出状态。所有产品均获得 UL、CSA、VDE 和 CQC 安全认证，并且采用宽体封装的产品支持用于承受高达 3.75 kVRMS 的增强型隔离。

规格摘要

单向通道：2

双向信道：0

隔离电压 (kVrms)：3.75

最大数据传输率：150

默认输出状态：低

封装类型：NB SOIC-8

　　· MAXELL CR1220 电池给RTC时钟做备用电池。36mAh容量，最大放电电流0.1mA，RTC的RX8130在后备电池3V供电时功耗最大500nA,可以工作10年以上。工业级温度范围，满足产品实际需求的-20~70℃范围。

【CR1220】

锂二氧化锰电池，其命名是按IEC的标准命名。其中C-以锂金属为负极，以二氧化锰为正极的化学电池体系，R-表示电池的形状为圆柱形，如果是方形则F替代;12表示电池的直径是12.5mm,20代表电池的高度为2.0mm。

直流电能表是针对直流屏、太阳能供电、电信基站、地铁等应用场合而设计的，该系列仪表可测量直流系统中的电压、电流、功率、正向与反向电能。既可用于本地显示，又能与工控设备、计算机连接，组成测控系统。仪表可具有RS-485通讯接口，采用Modbus-RTU协议.

标称电压为3.0V，终止电压(end point voltage)为2.0V, 额定容量为40mAh，因厂家水平而异。随着新行业的要求，也有特殊改进的电池，其容量会很不一样，主要是改进其大电流的输出能力，如应用于闪灯或RF产品的。

该电池常用于数码产品及其他小电子产品的CMOS电池上、其他记忆功能或断电保护模块、电子辞典、LED发光或发声玩具礼品，等产品上。

1、正确连接电池的“+”/“-”极性;　2、不同种类的电池不要在一起使用;　3、不要直接将焊料加在电池上;　4、避免电池储存在直射光、高温、高湿的环境下。

通常情况是1年寿命，如果生产厂家制造水平不高，或品质控制不好，其寿命会大大缩短。国内一线品牌的电池基本可保证这个寿命。如使用环境很理想(密封，常温，无水份等干扰)其寿命会进一步延长，可达3年。国内锂二氧化锰电池经过近几年的不断改进，性能已越来越接近日本电池水平。

　　· EPSON RTC时钟RX8130CE掉电时纽扣电池供电，后备电池供电，典型值300nA，超低功耗。2.5mm*3.2mm大小对实现小型化的设计贡献极大。价格便宜，与普通RTC芯片价格相当，且无需外接晶振，更加节省BOM成本。

      【RX8130CE】