The polarity of the current sources on ECGP and ECGN can
be reversed by selecting P (Pull-down), N (Pull-up). This is
useful if electrode polarities are reversed.
When AC is selected for ‘Lead-Off Mode’, the AC lead-off
detection uses a square-wave current source with the
frequency defined in the ‘Lead-Off Drive Frequency’.
ECG RLD Tab
This tab is used to enable and configure the right leg drive (RLD) circuit. The RLD circuit improves
system-level common-mode rejection of signals coupled to the user from the environment, primarily 50Hz
or 60Hz power-line interference. When RLD is enabled, the circuit senses the AC common-mode input
signal from the input electrodes, inverts, and amplifies the signal, and drives it onto the body through a
third electrode. This has the effect of attenuating the common-mode signal at the inputs and driving them
toward a selectable reference voltage, typically VMID_ECG. This also ensures proper common-mode
biasing of the electrodes, allowing the internal lead bias resistors to be disabled. Alternatively, the RLD
circuit can also act as a DC body-bias buffer. See the available options in Table 10 for more details.
Figure 59. ECG RLD Tab
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