原标题：TI ADS131M04单相电表参考设计TIDA－010036

TI公司的TIDA-010036是采用24位32kSPS四路同时取样delta-sigma(ΔΣ)数模转换器(ADC) ADS131M04的单相电表参考设计.高性能ARM® Cortex®-M4 MCU实现计量计算和8kHz取样速率,增加了电源质量功能如单个谐波分析. 参考设计具有Class 0.5单相计量测试,输入电流50mA到90A,电表计量的参数包括有功和无功能量与功率,RMS线电流,RMS零线电流,RMS电压,功率因素和线频率, 检测潜在的篡改攻击,具有低功耗电流检测模式,紧凑非磁性电源,并带有电源良好指示和电源故障告警,具有RS-485和RS-232接口, 5-kVRMS隔离.本文介绍了24位ADC ADS131M04主要特性,功能框图和应用框图, 分相法设计前端框图以及参考设计TIDA-010036主要特性和主要指标,框图,电路图,材料清单和PCB设计图.

ADS131M04 4-Channel, Simultaneously-Sampling, 24-Bit, Delta-Sigma ADC The ADS131M04 is a four-channel, simultaneously sampling, 24-bit, delta-sigma (ΔΣ), analog-to-digital converter (ADC) that offers wide dynamic range, low power, and energy-measurement-specific features, making the device excellent for energy metering,power metrology, and circuit breaker applications.

The ADC inputs can be directly interfaced to a resistor-divider network or a power transformer to measure voltage or to a current transformer or a Rogowski coil to measure current.

The individual ADC channels can be independently configured depending on the sensor input. A lownoise, programmable gain amplifier (PGA) provides gains ranging from 1 to 128 to amplify low-level signals. Additionally, this device integrates channelto- channel phase calibration and offset and gain calibration registers to help remove signal chain errors. A low-drift, 1.2-V reference is integrated into the device reducing printed circuit board (PCB) area.

Cyclic redundancy check (CRC) options can be individually enabled on the data input, data output, and register map to ensure communication integrity.

The complete analog front-end (AFE) solution is offered in a 20-pin TSSOP or leadless 20-pin WQFN package and is specified over the industrial temperature range of –40℃ to +125℃.

The ADS131M04 is a low-power, four-channel, simultaneously sampling, 24-bit, delta-sigma (ΔΣ) analog-to digital converter (ADC) with a low-drift internal reference voltage. The dynamic range, size, feature set, and power consumption are optimized for cost-sensitive applications requiring simultaneous sampling.

The ADS131M04 requires both analog and digital supplies. The analog power supply (AVDD – AGND) can operate between 2.7 V and 3.6 V. An integrated negative charge pump allows absolute input voltages as low as 1.3 V below AGND, which enables measurements of input signals varying around ground with a single-ended power supply. The digital power supply (DVDD – DGND) accepts both 1.8-V and 3.3-V supplies. The device features a programmable gain amplifier (PGA) with gains up to 128. An integrated input precharge buffer enabled at gains greater than 4 ensures high input impedance at high PGA gain settings. The ADC receives its reference voltage from an integrated 1.2-V reference. The device allows differential input voltages as large as the reference. Three power-scaling modes allow designers to trade power for ADC dynamic range.

Each channel on the ADS131M04 contains a digital decimation filter that demodulates the output of the ΔΣ modulators. The filter enables data rates as high as 32 kSPS per channel in high-resolution mode. The relative phase of the samples can be configured between channels, thus enabling an accurate compensation for the sensor phase response. Offset and gain calibration registers can be programmed to automatically adjust output samples for measured offset and gain errors. Functional Block Diagram section provides a detailed diagram of the ADS131M04.

The device communicates via an serial programming interface (SPI)-compatible interface. Several SPI commands and internal registers control the operation of the ADS131M04. Other devices can easily be added to the same SPI bus by adding discrete CS control lines. The SYNC/RESET pin can be used to synchronize conversions between multiple ADS131M04 devices as well as to maintain synchronization with external events.

ADS131M04主要特性:

• 4 simultaneously sampling differential inputs
• Programmable data rate up to 32 kSPS
• Programmable gain up to 128
• Noise performance:
– 102-dB dynamic range at gain = 1, 4 kSPS
– 80-dB dynamic range at gain = 64, 4 kSPS
• Total harmonic distortion: –100 dB
• High-impedance inputs for direct sensor connection:
– 300-kΩ input impedance for gains of 1, 2, and 4
– 1-MΩ input impedance for gains of 8, 16, 32, and 64
• Programmable channel-to-channel phase delay calibration:
– 244-ns resolution, 8.192-MHz fCLKIN
• Current detect mode allows for super low power tamper detection
• Fast startup: first data within 0.5 ms of supply ramp
• Integrated negative charge pump allows input signals below ground
• Crosstalk between channels: –120 dB
• Low-drift internal voltage reference
• Cyclic redundancy check (CRC) on communications and register map
• 2.7-V to 3.6-V analog and digital supplies
• Low power consumption: 3.3 mW at 3-V AVDD and DVDD
• Package: 20-pin TSSOP or 20-pin WQFN
• Operating temperature range: –40℃ to +125℃

ADS131M04应用:

• Electricity meters: commercial and residential
• Circuit breakers
• Battery test equipment
• Battery management systems

图1. ADS131M04功能框图

图2. ADS131M04应用框图(1)

图3. ADS131M04应用框图(2)

图4. ADS131M04多个器件配置图

图5. ADS131M04分相法设计前端框图

参考设计TIDA-010036

This reference design implements Class 0.5 single phase energy measurement using standalone multichannel analog-to-digital converters (ADC) to sample a shunt current sensor. With the combination of the shunt sensor and a compact magnetically immune 
power supply, the design provides protection against magnetic tampering attacks. The design also provides the capability to detect potential tampering from neutral line disconnection. The combination of a high performance ARM® Cortex®-M4 MCU to execute the metrology calculations and 8-kHz sampling rate allows the addition of power quality functions, such as individual harmonic analysis.

参考设计TIDA-010036主要特性:

• Class 0.5 single-phase metrology tested across 50-mA to 90-A input range
• Calculated parameters include active and reactive energy and power, RMS line current, RMS neutral current, RMS voltage, power factor, and line frequency
• Detects potential tamper attacks with low-power current-detection mode
• Compact non-magnetic power supply with power good indication and supply failure alerts
• RS-485 and RS-232 interfaces with 5-kVRMS isolation

参考设计TIDA-010036应用:

• Electricity meter
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图6. 参考设计TIDA-010036外形图

图7. 参考设计TIDA-010036框图
参考设计TIDA-010036主要指标:


图8. 参考设计TIDA-010036电路图(1)

图9. 参考设计TIDA-010036电路图(2)

图10. 参考设计TIDA-010036电路图(3)

图11. 参考设计TIDA-010036电路图(4)

图12. 参考设计TIDA-010036电路图(5)

图13. 参考设计TIDA-010036电路图(6)

图14. 参考设计TIDA-010036电路图(7)
参考设计TIDA-010036材料清单:




图15. 参考设计TIDA-010036 PCB设计图(1)

图16. 参考设计TIDA-010036 PCB设计图(2)

图17. 参考设计TIDA-010036 PCB设计图(3)

图18. 参考设计TIDA-010036 PCB设计图(4)

图19. 参考设计TIDA-010036 PCB设计图(5)

图20. 参考设计TIDA-010036 PCB设计图(6)

图21. 参考设计TIDA-010036 PCB设计图(7)

图22. 参考设计TIDA-010036 PCB设计图(8)