Hello everyone.

I want to incorporate Interlogix 5150 sensors (https://www.interlogix.com/intrusion/product/5150-series) into my alarm system, which is basically a PLC with an input impedance of 5.8KΩ.
The 5150's are 2-wire, non-polarized devices, powered by the input loop current (approx 2mA):
-the un-tripped ON state is 14Ω typ,
-the tripped OFF state is 1 MΩ for 5 seconds.
With these values, my assumption is the output device is back-to-back MOSFETs, normally turned on.
How do they store enough energy for 5s (this is a small device with no place for an electrolytic capacitor).

I am reluctant to incorporate these into my system without knowing the circuit.
Has anyone opened one of these units and reversed-engineered it?
Any info would be appreciated.

MartyK

 

Hi Martyk, it sounds feasible to have back-to-back MOSFETs doing the work like you say, but then if so they take no real current to switch on / off. You can actively switch them on (taking power to do so) and then once triggered and switched off, have a very high value resistor slowly charging up the gate again until they switch back on (ie after 5 seconds).
Then again, some small ceramic SMD capacitors could easily be incorporated if they needed to.

 

Hello everyone.

I want to incorporate Interlogix 5150 sensors (https://www.interlogix.com/intrusion/product/5150-series)

The 5150's are 2-wire, non-polarized devices, powered by the input loop current (approx 2mA):

The datasheet explicitly states the device is self powered. Where are you getting the 2ma loop power requirement? Is there another document?

 

The datasheet explicitly states the device is self powered. Where are you getting the 2ma loop power requirement? Is there another document?

"Self powered" only means this is a 2-wire device, unlike others that have 4 wires.
I measured the 2mA.