Principle of operation and terms related to "INHIBIT"
Term: INHIBIT is an external signal, that switches off the high voltage for the device or a specific channel
Logic / Signal Level Standard:
The INHIBIT - signal has negative logic, which means it is LOW-active. When applying a TTL-Low-level on INHIBIT input the signal will be rated as ACTIVE, the high voltage generation will be switched off.
Default state = state at non wired signal input:
By applying of Pull-Up or Pull-Down resistors the Default - state will be defined.
Case 1: INHIBIT: Default inactive (=> high voltage is generated)
=> signal input has HIGH - level => pull-up resistor after Vcc
Switch off of HV by applying 0V on signal input
Case 2: INHIBIT: Default active (=> high voltage is not generated):
=> signal input has LOW - level => pull-down resistor after 0V
Switch on of HV by applying Vcc on signal input
Logic / signal level negated
The INHIBIT signal has positive logic, that means it is HIGH-active. By applying of TTL-High-Level
on INHIBIT input the signal will be rated as ACTIVE, the high voltage generation will be switched
Default-State = state at non wired signal input:
Case 3: INHIBIT: Default inactive (=>high voltage is not generated):
=> Signal input as LOW-level => Pull-Down resistor after 0V
Switch off of HV by applying of Vcc on signal input
Case 4: INHIBIT: Default active (=>high voltage is not generated):
=> Signal input has HIGH-level => Pull-Up resistor after Vcc
Switch on of HV by applying of 0V on signal input
Specifics of NHQ version (NHQ_HPGe) for High Purity Germanium (HPGe) - Detectors
High Purity Germanium (HPGe) detectors often depend on a safety function of the cooling system to prevent damages to the detector in case of a malfunction of the cooling System. Therefore, for example the cooling systems of ORTEC HPGe detectors send out an analogue signal ("HPGe warm up") to trigger the attached High Voltage power supply to shut down, so there is no high voltage connected to the detector in case the cooling is not working efficiently enough.
iseg also offers it's NHQ power supplies equipped with the standard shut-down signal INHIBIT changed to the specific signals of the ORTEC cooling systems. Equipped with this adaptation, the NHQ High Voltage Power supply will only provide output voltage as long as the analogue signal coming from the cooling system is between -24V and -10.9V.