NetComm NTC-220 User Manual page 189

Power detection (Ignition) input
The Power detection or Ignition input will detect the presence of three states from the connector side (outside
world). It will detect three states, those being High, Low and Unconnected (floating).
The detection uses both analogue and digital inputs to the microprocessor.
This is the "LOW" state:
If input voltage at POWER port is less than 0.5V the transistor Q1 is shut, POWER FAIL is asserted high
advising micro that no Backup Power is present on POWER port.
This is the "Floating" state:
If voltage at POWER port is 0.5-3V POWER FAIL signal de-asserts but POWER MON signal can be measured
by ADC of micro and advise the system that there is little or no connection to the unit.
This is the "HIGH" state:
If voltage at POWER port is higher than 3.3V (which normally is an indication of presence of decent power
source), the POWER FAIL is still de-asserted, the POWER MON will measure from 3.3V up to whatever
voltage is detected. The maximum detection voltage is 30V and clamps to anything above 36V.
The states can be adjusted in software to fine tune the transition points between the states.
NTC-220 – User Guide
UG01028 v1.2 March 2019
189 of 193
© NetComm Wireless 2019