Isolated, High-Accuracy Analog Input Module Reference Design Using 16-Bit ADC and Digital Isolator

(ACTIVE) TIDA-01214

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Key Document

Description

This reference design provides accurate measurements of AC voltage and current inputs using a precision 16-bit SAR ADC over a wide input range, covering protection and measurement range (including sampling requirements of IEC 61850-9-2), simplifying system design and improving trip time performance and reliability. The analog input module (AIM) is isolated from the host processor using a digital isolator with an integrated power. For a limited function and cost optimized  design approach, An AC AIM can be designed using only three TI products, reducing system cost and board size. The alarm feature identifies the AC analog input faults on a sample basis for faster fault detection. The ADC has an additional auxiliary channel to diagnose the supply output of the digital isolator. A 12-bit ADS8668 ADC with a gain amplifier can increase the dynamic range by using programmable internal ranges, further optimizing the system cost.

Features
  • This reference design is based on ADS8688A 16-bit SAR ADC and supports measurement of up to 16 analog inputs by daisy chaining
  • ADC interface isolated from host for improved safety in harsh operating conditions using ISOW7841 with integrated power converter providing current output of > 60 mA with efficiency ≥ 45%
  • AC AIM provides ENOB of > 14.9 bits, SNR of > 91 dB, and THD of > –110 dB
  • 12-bit ADC8668 with front-end gain amplifier for increasing dynamic range of low-voltage output sensors in cost-optimized applications
  • Load switch used at input of ISOW7841 to protect AC AIM during output overload

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Bill of Materials (BOM)

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TI Devices (33)

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Part Number Name Product Family Sample & Buy Design Kits & Evaluation Modules
ADS8668  12-Bit 500kSPS 8-Channel SAR ADC With Bipolar Inputs Off 5V Supply  Analog-to-digital converters (ADCs)  Sample & Buy View Design Kits & Evaluation Modules
ADS8678  14-Bit 500kSPS 8-Channel SAR ADC With Bipolar Inputs Off 5V Supply  Analog-to-digital converters (ADCs)  Sample & Buy View Design Kits & Evaluation Modules
ADS8688  16-Bit 500kSPS 8-Channel Single-Supply SAR ADC With Bipolar Input Ranges  Analog-to-digital converters (ADCs)  Sample & Buy View Design Kits & Evaluation Modules
ADS8688A  16-Bit 500kSPS 8-Ch SAR ADC With Bipolar Inputs Using 5V Supply and Low-Drift Vref  Analog-to-digital converters (ADCs)  Sample & Buy View Design Kits & Evaluation Modules
ADS8698  18-Bit 500kSPS 8-Channel SAR ADC With Bipolar Inputs Off 5V Supply  Analog-to-digital converters (ADCs)  Sample & Buy View Design Kits & Evaluation Modules
CSD17571Q2  30V N-Channel NexFET Power MOSFETs, CSD17571Q2  MOSFETs  Sample & Buy View Design Kits & Evaluation Modules
INA333  Low-Power, Zero-Drift, Precision Instrumentation Amplifier  Amplifiers  Sample & Buy View Design Kits & Evaluation Modules
ISO7741  High-Speed, Low-Power, Robust EMC Quad-Channel Digital Isolator  Isolation  Sample & Buy View Design Kits & Evaluation Modules
ISO7841  High-Immunity, 5.7kVRMS Reinforced Quad-Channel 3/1 Digital Isolator, 100Mbps  Isolation  Sample & Buy View Design Kits & Evaluation Modules
ISOW7841  High-Efficiency, Low-Emissions, Reinforced Digital Isolator With Integrated Power  Isolation  Sample & Buy View Design Kits & Evaluation Modules
LM27762  Low-Noise Positive- and Negative-Output Charge Pump With Integrated LDO  DC/DC switching regulators  Sample & Buy View Design Kits & Evaluation Modules
LM5001  3.1-75V Wide Vin, 1A Current Mode Non-Synchronous Switch Mode Regulator  Step-up (boost)  Sample & Buy View Design Kits & Evaluation Modules
LMT70  ±0.1°C Precision Analog Temperature Sensor  Temperature sensors  Sample & Buy View Design Kits & Evaluation Modules
OPA320  Precision, Zero-Crossover, 20MHz, 0.9pA Ib, RRIO, CMOS Operational Amplifier  Operational amplifiers (op amps)  Sample & Buy View Design Kits & Evaluation Modules
OPA322  20MHz Low-Noise 1.8V RRIO CMOS Operational Amplifier With Shutdown  Operational amplifiers (op amps)  Sample & Buy View Design Kits & Evaluation Modules
OPA376  Precision, Low Noise, Low Iq Operational Amplifier  Operational amplifiers (op amps)  Sample & Buy View Design Kits & Evaluation Modules
OPA4180  0.1 uV/C Drift, Quad, Low Noise, Rail-to-Rail, 36V Zero Drift Op Amp  Operational amplifiers (op amps)  Sample & Buy View Design Kits & Evaluation Modules
REF5040  Low Noise, Very Low Drift, Precision Series Voltage Reference  Voltage references  Sample & Buy Not Available
REF6041  5ppm/C High-Precision Voltage Reference with Integrated High-Bandwidth Buffer  Voltage references  Sample & Buy View Design Kits & Evaluation Modules
REG71055  60-mA, 5.5V, Buck/boost Charge Pump in ThinSOT-23  DC/DC switching regulators  Sample & Buy View Design Kits & Evaluation Modules
SN6505B  Low-Noise 1-A , 420kHz Transformer Driver for Isolated Power Supplies  Isolation  Sample & Buy View Design Kits & Evaluation Modules
SN74LVC1G17  Single Schmitt-Trigger Buffer  Buffer/driver  Sample & Buy View Design Kits & Evaluation Modules
TLV3012  Nanopower, 1.8V, SOT23 Push-Pull Comparator with Voltage Reference  Amplifiers  Sample & Buy View Design Kits & Evaluation Modules
TPS22944  5.5V, 0.2A, 500mΩ, 100mA Current Limit Load Switch  Power switches  Sample & Buy View Design Kits & Evaluation Modules
TPS3808  Low Quiescent Current Supervisor with Programmable-Delay  Power management  Sample & Buy View Design Kits & Evaluation Modules
TPS3836  NanoPower Supervisory Circuits  Power management  Sample & Buy View Design Kits & Evaluation Modules
TPS60241  170 uVrms Zero-Ripple Switched Cap Boost Converter With Fixed 5.0V Output For VCO Supply  DC/DC switching regulators  Sample & Buy View Design Kits & Evaluation Modules
TPS60403  60mA Charge Pump Voltage Inverter with Fixed 250kHz Operation  DC/DC switching regulators  Sample & Buy View Design Kits & Evaluation Modules
TPS61040  28-V, 400-mA Switch Boost Converter in SOT-23 for LCD and White LED Applications  Step-up (boost)  Sample & Buy View Design Kits & Evaluation Modules
TPS717  150mA, High PSRR, Low Quiescent Current, Low Noise LDO  Power management  Sample & Buy View Design Kits & Evaluation Modules
TPS723  200mA Negative-Output Low-Dropout (LDO) Linear Regulator  Power management  Sample & Buy Not Available
TPS791  Ultralow Noise, High PSRR, Fast RF 100-mA Low-Dropout Linear Regulators  Power management  Sample & Buy View Design Kits & Evaluation Modules
TPS7A49  Vin 3V to 36V, 150mA, Ultra-Low-Noise, High-PSRR Low-Dropout (LDO) Linear Regulator  Power management  Sample & Buy View Design Kits & Evaluation Modules

CAD/CAE symbols

Part # Package | Pins CAD File (.bxl) STEP Model (.stp)
ADS8698 Download -
CSD17571Q2 WSON (DQK)| 6 Download Download
INA333 Download Download
Download -
ISO7741 Download Download
Download Download
ISO7841 Download Download
SOIC (DWW)| 16 Download Download
ISOW7841 Download Download
LM27762 Download
LM5001 Download Download
Download Download
LMT70 Download -
OPA320 Download Download
OPA322 Download Download
Download -
OPA376 Download Download
Download Download
Download Download
OPA4180 Download
Download
REF5040 Download Download
Download Download
REF6041 Download Download
REG71055 Download Download
SN6505B Download Download
SN74LVC1G17 Download -
Download -
Download Download
Download Download
Download
Download Download
Download Download
Download Download
TLV3012 Download Download
Download Download
TPS22944 Download Download
TPS3808 Download Download
Download Download
TPS3836 Download Download
TPS60241 Download Download
TPS60403 Download Download
TPS61040 Download Download
Download -
Download Download
TPS717 Download Download
Download Download
Download Download
TPS723 Download Download
TPS791 Download
Download
TPS7A49 Download Download
Download Download

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Technical Documents

View the Important Notice for TI Designs covering authorized use, intellectual property matters and disclaimers.

User guides (1)
Title Abstract Type Size (KB) Date Views TI Recommends
PDF 929 17 Aug 2018 31
Design files (6)
Title Abstract Type Size (KB) Date Views
ZIP 2975 05 Sep 2017 21
ZIP 7943 05 Sep 2017 33
ZIP 4008 05 Sep 2017 22
ZIP 716 05 Sep 2017 20
ZIP 520 05 Sep 2017 22
ZIP 1254 05 Sep 2017 74

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