EMC Compliant, Group Isolated, 2-Channel Binary Input Module for Wide AC/DC Input Reference Design
1 января 2018
The TIDA-00809 TI 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 a MCU integrated 10-bit analog-to-digital converter (ADC) to measure with in ±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 (20mA-50mA, 50ms) using MCU PWM output to remove the contamination (anti-burnishing) on the binary input contacts