AD8232 Evaluation Board User Guide

Hello Gustavo,

Reffering to the following part of the AD8232 evaluation board wiki:

"Note that the electrode interfaces +VIN, -VIN and RLD are equipped with 180kΩ and 499kΩ (R6, R7 and R1 respectively) resistors to limit current injection to the subject in the event of fault or overload. Please note that these will not protect against supply line transients coming through the system. Isolation from the power line is always required when connecting to a live subject. It is recommended to fully understand common safety practices; the proper application of such guidelines is sole responsibility of the end user."

Why would this power line isolation be necessary if you are connecting to a 3V battery or similar?

Thanks in advance.

Stephen

Hello Stephen,

All electronic equipment that is meant to interface to live subjects (humans, animals, etc) must be isolated from the power line for safety reasons. The purpose of that statement is to remind users of that fact. The user is responsible for making sure the setup is safe and harmless, and that we are not liable for any misuse or improper connections. The evaluation board only delivers a convenient way to evaluate the IC. It has not (nor is meant) been qualified for safety.

I am not familiar with your particular setup, and I am not qualified to give safety advice. There is plently of literature on the subject. If you need further help, I can recommend the book "Medical Instrumentation" by John Webster. Chapter 14 (fourth edition) contains a good primer on electrical safety.

Regards,

Gustavo