Are the bus and shunt voltage of the diasabled channel considered 0v?
or totally exclude from every calculation?[ex)power valid alert, critical alert, summation alert]
Hello value engineer,
If you disable any channel through configuration register, then the device's internal ADC will stop measuring this channel. So the measurement register will remain the last measured value before it was disabled. You should not have to worry about a critical or warning alert for any disabled channels because the alert limits are by default set to maximum full-scale range, thus effectively disabled.
Since the device is programmed to power up with default settings to measure all three channels in shunt and bus voltage continuous mode AND PV_upper limit (register 2710h) set to 10V, then device will likely make a determination of Power Valid status before the host MCU/processor programs it to desired settings. After device is programed to disable a channel, the PV status will remain unchanged because there is no new incoming VBUS data to refresh the status. Thus, you cannot trust PV status when one of the channels is disabled, unless you are connecting IN- (from unused channel) to the IN- of used channel. See below for PV status information in datasheet.
Lastly, as for the summation alert, this value (register 0dh) is the summation of only the channels selected in mask/enable register (0Fh bits 14-12). So for example, if you have disabled Channel 2 measurements in configuration register, then you will want to also disable Channel 2 in mask/enable register (bit 13 = 0) with bits 14 (Ch1) and 12 (Ch3) set to 1 (enabled).
Hope this all make sense. Post back with any other questions.
Best,
Peter
