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I am using ECG signal conditioning chip called AD8232. It takes 3 inputs, namely, right arm (RA), left arm (LA) and Right leg (RL) & gives one analog output as the ECG signal. According to einthoven's triangle for ECGs, there can be 3 leads (Lead I/II/III) can be obtained from the 3 electrodes connected, so for this chip, which lead is the output? I couldn't find anything in the datasheet.

Gagan G
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3 Answers3

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Why doesn't Analog Devices show a schematic of an ECG circuit like this one: ECG

Audioguru
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If you connect the non-inverting input to the left arm and the inverting input to the right arm, you get Lead I.

enter image description here

source

The datasheet doesn't say explicitly because you can connect the two input electrodes to different positions, but it does mention this typical connection:

enter image description here

devnull
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Answered on Reddit (by user - Assembler Guy)

Which lead vector you get depends on where you stick the two input electrodes ("RA" and "LA", or rather "IN-" and "IN+"). If you place them in their nominal position, you get lead I, but if you place the "LA" electrode in the "LL" position, you get lead II. With only two input electrodes, there is no way to get aVx vectors or chest vectors.

"RL" is probably not used as an input, but instead as output for the a driven-right-leg feedback loop to reduce common-mode interference. The diagram appears to indicate this:

https://www.analog.com/en/products/ad8232.html

Gagan G
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