Applications of particular interest for the INA333 are portable ECG systems or heart rate monitors. In an ECG application, the action potential created by the heart wall contraction spreads electrical currents from the heart throughout the body. This creates different potentials at different points on the body which can be sensed by electrodes on the skin surface. The signal amplitude is generally around 1 to 2mV peak-to-peak, with measurement difficulties coming in due to the presence of a large DC offset from the electrode to skin interface and 50/60 Hz noise interference from power supplies, RF interference, or even pace makers. The INA333 offers a high 100 dB CMRR to reduce the 50/60 Hz line noise common to both inputs, as well as offering 20uV of offset keeping the measurement error below 2% on a 1mV signal. Additionally, the 75uA supply current and 1.8V supply enables maximum power efficiency and extends the life of the battery.