My project need to measure two channels ECG signal and using ads1292. There are 4 leads, such as IN1P , IN2P, RD and COM, which COM is a common electrode with connecting IN1N and IN2N together. I select DC lead-off detection method. When the RD is on, it is usually normal. But when the RD is off, the LOFF state of the other leads sometimes are unstable like a trapezoid wave with 50Hz frequency no matter that lead is off or on. So i think the lead detection is disturbed by power frequency. And i choose various LOFF current magnitudes and comparator thresholds with LOFF register to avoid this problem, but it doesnot work.
How can i fix it. Thanks.
figure2:LOFF state output with 50Hz