overcurrent protection PolySwitch (RXEF110), trip and hold A?

hi,

I'm not sure I understand the difference between the Hold A and Trip A. When the current reaches the Hold A the polyswitche's resistance increases but what happens the the current reaches the Trip A mark?

as an example the RXEF110 has a hold value of 1.10 A and a trip value of 2.20A.

http://datasheet.octopart.com/RXEF110-Tyco-Electronics-datasheet-14475427.pdf

With hold current being the “safe” amount of current the device will pass, after the hold current is reached the internal resistance changes until the trip current is reached where the PTC heats and inside the material changes state and “TRIPS”. It is then essentially open until such time passes and it cools back to acceptable operating temperature and closes.

Hold current is safe current value.
Trip current is like current rating on a fuse which is the value the circuit opens.

I thought trip current is the current needed to put it in high resistance state and hold current was the current that then keeps it hot enough to stay tripped. In other words there is some hysteresis.

I believe that current keeping it in the high resistance state (or tripped) is leakage current.

I believe that current keeping it in the high resistance state (or tripped) is leakage current.

These devices will not stay in the high resistance state when tripped. They will oscillate until the overload condition is removed.