MKS HPQ3, Hardware Manual

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MKS Instruments UK Ltd
HPQ3 Hardware Manual – SP101019.101 October 2012
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2.1 X-Trip
The X-Trip connector requires a special locking, stereo jack plug, which is supplied with the unit.
Do not use a standard 3.5mm jack plug. Replacements are available from MKS Instruments if
required.
The external trip feature is used to protect the filaments and electron multiplier from exposure to
high pressures. It allows an independent total pressure gauge or signal from a vacuum control
system to be connected to the HPQ3 as protection against accidental damage.
It is the most effective of the trips available and we would always recommend its use.
The external trip input can be driven in three ways:
1. Uncommitted relay contact
This is a low voltage (+5V, 1mA) contact. The contact should be closed for normal operation, open
to trip the filaments, or if the protective equipment is switched off.
2. Open collector TTL drive
The output transistor should be on for normal operation, off for trip, or if the protective equipment is
turned off.
3. Totem pole TTL drive
The signal should be low for normal operation, high for a trip condition, or if the protective
equipment is switched off.
The external trip circuitry is galvanically isolated from the system ground. The maximum common
mode voltage is 60V DC or peak AC, current limited to 2mA.
2.2 Audio Socket
This is a 2.5mm jack socket. It is used to connect headphones or an external amplified speaker so
that audio tones generated in some of the modes can be heard. E.g. Leak checking tone and audio
alarms.
The minimum load impedance should be 8 ohms and the power handling is 2 watts max.