EMC Compliant, Group Isolated, 2-Channel Binary Input Module for Wide AC/DC Input Reference Design


Design files


This reference design showcases a cost-optimized architecture that improves resolution of a binary-input module. A microcontroller unit (MCU) is shared between two-input channels (group isolation) to minimize the cost per channel. Wide-input range is covered using an amplifier with gain and MCU-integrated 10-bit analog-to-digital converter (ADC) to measure within ±3% accuracy. This architecture eliminates the need for multiple hardware versions based on input voltage range as is the case with an opto-coupler based topology. A digital isolator is used to communicate the ADC code or the root-mean-square estimate of the input to the host processor. The design is tested for ESD, EFT and surge as per IEC61000-4 Level 4.

  • Measurement accuracy: <±3% over a wide-input range for AC/ DC input using 10-bit SAR ADC
  • MCU shared between two channels (group isolation) to minimize cost per channel with additional unassigned input channels for larger channel count group isolation
  • Wide-input range covered using an amplifier with two gain stages
  • Choice of basic or reinforced isolation between input and the host processor using digital isolator
  • Onboard current pulse generator (20 mA to 50 mA, 50 ms) using MCU PWM output to remove the contamination (anti-burnishing) on the binary input contacts
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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

Download ready-to-use system files to speed your design process.


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

TIDRMR7.ZIP (3252 K)

Files used for 3D models or 2D drawings of IC components


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.

MSP430 microcontrollers

MSP430G233216 MHz MCU with 4KB Flash, 256B SRAM, 10-bit ADC, SPI/I2C, timer

Data sheet: PDF
Digital isolators

ISO7320CLow-power, dual-channel, 2/0, 25-Mbps digital isolator

Data sheet: PDF | HTML
Digital isolators

ISO7820Highest isolation rating, dual-channel, 2/0, reinforced digital isolator

Data sheet: PDF | HTML
General-purpose op amps

LMV551Single, 5.5-V, 3-MHz, low quiescent current (37-μA) operational amplifier

Data sheet: PDF | HTML
General-purpose op amps

LMV614Quad, 5.5-V, 1.5-MHz, RRIO operational amplifier

Data sheet: PDF | HTML
I2C isolators

ISO15412.5-kVrms, isolated unidirectional clock, bidirectional I2C isolator

Data sheet: PDF | HTML
Linear & low-dropout (LDO) regulators

TPS709150-mA, 30-V, ultra-low-IQ, low-dropout voltage regulator with reverse current protection and enable

Data sheet: PDF | HTML
Shunt voltage references

LM4041BAdjustable, precision micropower shunt voltage reference with 0.2% accuracy

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 EMC Compliant 2-Channel Wide AC/DC Isolated Binary Input Module Design Guide (Rev. A) Oct. 07, 2016

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