Overview: POLYZEN DEVICES Polymer Protected Zener Diode PolyZen devices are polymer-enhanced, precision Zener diodes. They offer resettable protection against multi-Watt fault events without the need for multi-Watt heat sinks.
The Zener diode used for voltage clamping a PolyZen device was selected due to its relatively flat voltage vs. current response. This helps improve output voltage clamping, even when input voltage is high and diode currents are large.
An advanced feature of the PolyZen device is that the Zener diode is thermally coupled to a resistively nonlinear, PPTC (polymer positive temperature coefficient) layer. This PPTC layer is fully integrated into the device and is electrically in series between VIN and the diode clamped VOUT.
This advanced PPTC layer responds to either extended diode heating or overcurrent events by transitioning from a low to high resistance state, also known as “tripping.” A tripped PPTC will limit current and generate voltage drop. It helps to protect both the Zener diode and the follow-on electronics and effectively increases the diode’s power handling capability.
The polymer-enhanced Zener diode helps protect sensitive portable electronics from damage caused by inductive voltage spikes, voltage transients, incorrect power supplies and reverse bias. These devices are particularly suitable for portable electronics and other low-power DC devices.
