2-7
2.2.2.2 Principle diagram
Figure 2-5 Working principle of the ECG/RESP/TEMP module
2.2.2.3 Principle
This module collects the ECG, RESP and TEMP signals through the transducer, processes the
signals, and sends the data to the main board through the serial port.
ECG Signal Input Circuit
The input protection and filtering circuits receive the ECG signal from the transducer, and filter
the high-frequency interference signal to protect the circuit against the damage by defibrillator
high-voltage and ESD.
The right-leg drive circuit gets the 50/60Hz power common-mode signal from the lead cable, and
sends the negative feedback signal to the human body to reject the common-mode interference
signal on the lead cable, which helps the detection of the ECG signal.
The lead-off detecting circuit checks whether the ECG lead is off, and sends the information to
CPU.