Varistor for Industrial Quad Relay Bricklet

[thicks]

Hi,

 

What is the purpose of the Varistor in the Relay circuit.  Is it to protect the chip and route current away if Voltage from Emitter to Collector is to high? Maybe it has something to do with the reverse leakage current from the photodiode array?

 

Also, The Relay chip uses two MOSFETs.  Is the second one used to isolate something or maybe its also related to the leakage current?

[batti]

Hi,

 

What is the purpose of the Varistor in the Relay circuit.  Is it to protect the chip and route current away if Voltage from Emitter to Collector is to high? Maybe it has something to do with the reverse leakage current from the photodiode array?

The purpose of the varistor is to protect the mosfets for overvoltage.

 

Also, The Relay chip uses two MOSFETs.  Is the second one used to isolate something or maybe its also related to the leakage current?

To be honest, I didn't know. I could imagine that it is to decrease the leakage current.