原标题：TI ADS131E08S空气断路器高分辨率模拟前端参考设计TIDA-00661

　　TI公司的ads131e08s是具有快速加电的8路24位模拟前端(AFE),具有同时取样,内置可编程放大器(PGA) 24位delta-sigma (ΔΣ)模数转换器(ADC),内部基准电压和振荡器.加电时间3ms,1kSPS时的动态范围118dB,串扰-125dB,50Hz和60Hz的THD为-100dB,每路的功耗2mW,数据速率1, 2, 4, 8, 16, 32和64 kSPS,增益选择1,2,4,8和12.主要用在工业电源,断路器,继电器保护,电源监视和数据采集系统.本文介绍了ADS131E08S主要特性,框图,电源监视系统框图和ETU框图,以及空气断路器(ACB)用高分辨率和快速加电模拟前端参考设计TIDA-00661框图,主要特性,MCU板和ADC板主要特性,电路图和材料清单.

　　The ADS131E08S is a multichannel, simultaneoussampling, 24-bit, delta-sigma (ΔΣ), analog-to-digitalconverter (ADC) with built-in programmable gainamplifiers (PGAs), an internal reference, and aninternal oscillator. The ADC wide dynamic range,scalable data rates, and internal fault detect monitorsmake the ADS131E08S very attractive in industrialpower monitoring, control, and protectionapplications. Fast power-up time allows data to beavailable within 3 ms of power being applied to thedevice for line-powered power applications. Truehigh-impedance inputs enable the ADS131E08S to

　　directly interface with a resistor-divider network or avoltage transformer to measure line voltage, or acurrent transformer or Rogowski coil to measure linecurrent. With high integration levels and exceptionalperformance, the ADS131E08S enables the creationof scalable industrial power systems at a significantlyreduced size, power, and overall cost.

　　The ADS131E08S has an individual input multiplexerper channel that can be independently connected tothe internally-generated signals for test, temperature,and fault detection. Fault detection can beimplemented internal to the device, using theintegrated comparators with digital-to-analogconverter (DAC)-controlled trigger levels. TheADS131E08S can operate at data rates as high as64 kSPS.

　　The complete analog front-end (AFE) solution isavailable in a 64-pin TQFP package and is specifiedover the industrial temperature range of –40℃ to+105℃.

　　ADS131E08S主要特性:

　　• Power-Up Time: 3 ms

　　• Eight Differential Simultaneous Sampling Inputs

　　• High Performance:

　　– Dynamic Range at 1 kSPS: 118 dB

　　– Crosstalk: –125 dB

　　– THD: –100 dB at 50 Hz and 60 Hz

　　• Low Power Consumption: 2 mW/Channel

　　• Data Rates: 1, 2, 4, 8, 16, 32, and 64 kSPS

　　• Gain Options: 1, 2, 4, 8, and 12

　　• Internal Voltage Reference: 8 ppm/℃ Drift

　　• Supply Range:

　　– Analog:

　　– 2.7 V to 5.25 V (Unipolar)

　　– ±2.5 V (Bipolar)

　　– Digital: 1.7 V to 3.6 V

　　• Fault Detection and Device Self-Testing Capability

　　• SPI™ Compatible Data Interface and Four GPIOs

　　• Package: 64-Pin TQFP

　　• Operating Temperature Range: –40℃ to +105℃

　　ADS131E08S应用:

　　Industrial Power Applications:

　　Circuit Breakers, Protection Relays, Power

　　Monitoring

　　Data Acquisition Systems

　　空气断路器(ACB)用高分辨率和快速加电模拟前端参考设计TIDA-00661

　　A circuit breaker is an automatically-operated electrical switch that has been designed to protect anelectrical circuit from damage caused by overload. An overload occurs when too many devices areoperating on a single circuit, or when forcing a piece of electrical equipment to work beyond its designedcapabilities. A short circuit occurs when two bare conductors touch. When a short circuit occurs,resistance drops to almost zero. Short-circuit current can be thousands of times higher than a normaloperating current). The basic function of a circuit breaker is to detect a fault condition and, by interruptingcontinuity, immediately discontinue electrical flow. Breakers are available in different types.

　　• Low-voltage circuit breakers: These breakers are commonly used in domestic, commercial, andindustrial fields. Miniature circuit breakers (MCB), molded-case circuit breakers (MCCB), and air circuitbreakers (ACB) are common examples of low-voltage circuit breakers.

　　• Medium-voltage circuit breakers: These breakers can be assembled into metal-enclosed switchgearlineups for indoor applications or as individual components for outdoor applications like substations.

　　Vacuum circuit breakers, air circuit breakers, and SF6 circuit breakers are examples of mediumvoltagecircuit breakers.

　　• High-voltage circuit breakers: These breakers help to protect and control electrical power transmissionnetworks. These breakers are use solenoids for operation and employ the use of current sensingprotective relays that function through current transformers. Vacuum circuit breakers and SF6 circuitbreakers are examples of high-voltage circuit breakers.

　　Circuit breakers perform the following functions:

　　• Sensing – When an overcurrent occurs

　　• Measuring – The amount of overcurrent

　　• Acting – By tripping in a timely manner to prevent damage to the circuit breaker and the conductorsthat the breaker protects

　　The current-carrying capacity (in A) of the breaker must be higher than the expected load in the circuit.

　　This design highlights a signal processing front end foran electronic trip unit (ETU) for use with an air circuitbreaker (ACB). This subsystem uses a high-resolutiondelta-sigma (ΔΣ) ADC for measuring wide current andvoltage inputs within a specified accuracy; the subsystem can measure up to eight simultaneousinputs with 24-bit resolution. The ADC interfaces withan MSP430 MCU for input processing. This design ispowered with rectified current input or auxiliary DCinput power supplies. The design offers two options togenerate positive and negative power supplies, oneusing the LM5017 and the other with the LM5160configured in Fly-Buck mode. The purpose of using anETU in an ACB is to achieve fast and repeatable tripperformance for wide current inputs and widetemperature inputs. The ACB trips within

　　参考设计TIDA-00661主要特性:

　　• Three Voltage and Five Current Inputs Interfacedto 8-Channel, Simultaneous Sampling, 24-Bit ΔΣADC ADS131E08S With Fast Start-Up (< 3 ms)

　　• Measurement of AC Current Inputs With DynamicRange of ≤ 500 Within ±1% With Fixed PGA Gain

　　• Measurement of AC Input From 10 V to 750 VWithin ±1% With Fixed PGA Gain

　　• Onboard Potential Divider to Measure Voltage andBurden Resistors for Current Measurement

　　• Total Start-up Time of < 4 ms for ΔΣ ADC(ADS131E08S) to Measure Within ±2% of InputVoltage After Application of Auxiliary DC Input

　　• Current Measurement Accuracy of ±0.2% AchievedWith ADS131E08 for 0.2- to 100-A AC Input

　　• Voltage Measurement Accuracy of ±0.2% AchievedWith ADS131E08 for 5- to 1000-V AC Input

　　• DC-DC Converters Configured in Fly-Buck™Configuration to Generate Supply Outputs

　　• Accuracy Measurement With Low Power CurrentTransformer (LPCT) From 0.6 mV to 333 V (> 500Dynamic Range) Within ±0.2%

　　• Subsystem Configurable for 2- or 8-W PowerOutput

　　• Provision to Measure Three Current Inputs WithSingle Gain Interfaced to 12-Bit Internal ADC ofMCU for Earth Current Measurement

　　• Modular Design Provides Option to Interface ADCBoard to ADS131 EVM or MSP430 MCU

　　• Onboard LDOs to Generate 3.3 V and 5 V for MCUand ADC Boards, ±2.5 V and 3 V for ADC AnalogSupply

　　• ADC Inputs Protected Against ESD

　　参考设计TIDA-00661特性应用:

　　• ACB

　　• MCCB

　　• Recloser

　　• Feeder Protection Relay

　　参考设计TIDA-00661包括两种板:MCU板和ADC板

　　图.参考设计TIDA-00661外形图

　　MCU板包括:

　　• Fast start-up MSP430F5969 MCU for signal processing

　　• Fast start-up DC-DC converter for generating the supply for MCU and ADC boards

　　• Op amp and reference for signal conditioning the earth fault current input

　　• LDO to generate regulated supply for MCU and ADC board

　　• Undervoltage detector for MCU reset control

　　• Interface connector to connect to ADC

　　ADC板包括:

　　• Fast start-up, high-resolution ΔΣ ADC

　　• Current and voltage input including potential divider and protection

　　• Onboard temperature sensor

　　• Interface connector to connect to MCU board or MMB0 digital signal processing (DSP) board

　　MCU板材料清单:

　　ADC板材料清单:

　　详情请见:

ads131e08s.pdf

tidub80b.pdf