Circuit & System Protection


Resettable Zener/PPTC assemblies offer multistage protection

21 March 2007 Circuit & System Protection

Raychem's PolyZen is a polymer-enhanced, precision Zener diode micro-assembly. This device is designed to meet the growing need for over-current and over-voltage protection on portable equipment that uses barrel jacks for DC power input.

PolyZen can help protect sensitive electronics from damage caused by inductive voltage spikes, voltage transients, incorrect power supplies and reverse bias. The component incorporates a stable Zener diode for precise voltage clamping and a resistively non-linear, polymer positive temperature coefficient (PPTC) layer that responds to either diode heating or over-current events by transitioning from a low to high resistance state. Devices are capable of withstanding very high power fault conditions.

PolyZen devices are resettable, so they are effective against multiple fault events. In the event of sustained high power conditions, the PPTC element of the device trips to limit current and generate voltage drop. This functionality helps protect both the Zener and the secondary protection elements, effectively increasing the diode's power handling capacity.

These RoHS-compliant devices offer power handling up to 100 W and dissipate only 0,7 W.



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