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Tool/software:
for providing digital isolation I am planning to use ISO7741/ ISO7841 with analog SPI ADC ADS1018IDGST. can you please suggest your opinions and any specific recommendations for circuit designs.
Hi Bincy VK,
The ESD ratings for ADS1018-Q1 can be found in section 7.2 of the data sheet:
Note that this device is rated to 2kV for the HBM model in accordance with the ANSI/ESDA/JEDEC JS-001 specification.
Applying electrostatic discharge larger than the device rating may result in damage to the device.
To protect against a higher ESD voltage, it may help to have external protection for the device. TVS, Schottky diodes, or extra series resistance can be added to the analog inputs of the device.
The problem with adding too much input resistance is the amount of error added to the measurement. There is a certain amount of bias current being drawn from the ADS1018 due the switched capacitor input stage. Adding a large value resistance in series with the input will cause an error due to the voltage drop across the resistor. It is best to keep this input series resistance to 1k or below to avoid this measurement error.
From a rule of thumb and EMI/EMC standpoint, it is recommended tying your boards' GND or return to the same voltage or reference.
It might be helpful to check out this app note where we look into EMC compliance testing. It might give you some other tips about layout and other helpful information:
EMC Compliance Testing for Precision ADC Systems (Rev. A)
Here are some additional resources that might help:
Getting started with interface protection | TI.com
Circuit for protecting ADS131M0x ADC from electrical overstress
Design considerations for system-level ESD circuit protection
Best Regards,
Angel
