解释如下：
Both the two lead-off methods are used to inject a current onto the electrode wire and into the body. The current that is sourced by the resistor pull-up method will be higher than the programmable current sources = (AVDD - AVSS) / (2 * 10M). The AC lead-off detection feature uses the same current sources or resistors. The AC lead-off excitation signal is generated by chopping the lead-off sources back and forth between the positive and negative channel inputs (INxP and INxN).
