490NRP25400 Post Amplifier Circuit

The 490NRP25400 is a practical circuit in ECG detection circuit. The positive and negative inputs of the amplifier are connected to the left arm (LA) and the right arm (RA) of the human body through the electrocardiographic sensor, and the drive network composed of op-amp N and resistor R1~R4 is connected to the right leg (RL) of the human body, constituting a “floating ground”. As the biological signal is very weak, coupled with polarisation potential, so the amplification of the level should not be too high, generally taken between 10 ~ 100, and can only be used as a pre-amplifier, in order to detect the safety of the latter stage should generally be used to isolate the amplifier circuit to isolate the level of the power supply voltage should be used to isolate the power supply module should be used to provide the best to achieve the power supply and the signal of the complete isolation.

490NRP25400 has a high input impedance, low leakage current, high detection accuracy and meet the human body safety and other indicators can fully meet the requirements of medical equipment standards. The circuit is generally used as a pre-amplifier circuit, the device is in direct contact with the human body, and pick up the ECG signal through the INA115 for amplification, and finally isolated by ISO122 transmission to the rear amplifier circuit, to achieve the human body signal and the output and power supply isolation and amplification.