Shunt-Based 200A Peak Current Measurement Reference Design Using Isolation Amplifier


Design files


This reference design is for isolated current measurement using a shunt and isolated amplifier. By limiting the shunt voltage to 25 mV, this design is able to reduce power dissipation in the shunt and achieve a high-current measurement range of up to 200 A. Shunt voltage is further amplified by precision op amps in instrumentation amplifier-based configuration with a gain of 10 to match the input range of isolation amplifier. The output of isolation amplifier is level shifted and scaled to utilize the complete input range of 3.3-V ADC. This design uses a free-running transformer driver to generate isolated supply voltage for the high-voltage side of the circuit. Small form factor for the power supply is achieved by the operation of driver at 400 KHz.

  • Shunt-based isolated 200 Apk current measurement
  • Limiting shunt voltage to 25 mV helps achieve less power dissipation
  • High-side current sense circuit with high common-mode voltage of 1200-V peak supporting up to 690-V AC mains powered drives
  • Calibrated AC accuracy of <1% across temperatures -25˚C to +85˚C
  • Can be interfaced directly with differential- or single-ended ADC
  • Small form factor push-pull based isolated power supply to power high-side circuit
  • Inbuilt 1.65 VREF for level shifting the output
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A fully assembled board has been developed for testing and performance validation only, and is not available for sale.

Design files & products

Design files

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TIDUB91A.PDF (2056 K)

Reference design overview and verified performance test data


Detailed schematic diagram for design layout and components


Complete listing of design components, reference designators, and manufacturers/part numbers


Detailed overview of design layout for component placement

TIDRJH0.ZIP (1709 K)

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Design file that contains information on physical board layer of design PCB


PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

Isolated amplifiers

AMC1200±250-mV input, precision current sensing basic isolated amplifier

Data sheet: PDF | HTML
Isolated amplifiers

AMC1301±250 mV-Input Precision Reinforced Isolated Amplifier for Current Sensing

Data sheet: PDF | HTML
Precision op amps (Vos<1mV)

OPA2376Dual, precision, low-noise, low quiescent current operational amplifier

Data sheet: PDF | HTML
Precision op amps (Vos<1mV)

OPA376Precision (0.025mV), low noise (7.5nV/rtHz), low quiescent current (760uA) op amp

Data sheet: PDF | HTML
Series voltage references

REF20333.3-V Vref, low-drift, low-power, dual-output Vref & Vref/2 voltage reference

Data sheet: PDF | HTML
Shunt voltage references

LM4040Fixed voltage, 45-µA, precision micropower shunt voltage reference

Data sheet: PDF | HTML
Shunt voltage references

LM4040-N100-ppm/°C precision micropower shunt voltage reference

Data sheet: PDF
Transformer drivers

SN6501Low-noise, 350-mA, 410-kHz transformer driver for isolated power supplies

Data sheet: PDF | HTML

Technical documentation

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Type Title Date
* Design guide Shunt Based 200A Peak Current Measurement Using Isolation Amplifier Design Guide (Rev. A) Mar. 05, 2016

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