GENERAL DESCRIPTION

Littefuse PolyZen devices are polymer-enhanced, precision Zener diode micro-assemblies. They offer resettable protection against multi-Watt fault events and spare the need for large heavy heat sinks.

A unique feature of the PolyZen micro-assembly is that the Zener diode is thermally coupled to a resistively non-linear, polymer PTC (Positive Temperature Coefficient) layer. This PTC layer is fully integrated into the device, and is electrically in series between VIN and the diode clamped VOUT.

This polymer PTC 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 PTC 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.

FEATURES

• Overvoltage transient suppression

• Stable VZ vs fault current

• Time delayed, overvoltage trip

• Time delayed, reverse bias trip

• Multi-Watt power handling capability

• Integrated device construction

• RoHS Compliant and Halogen Free

BENEFITS

• Stable Zener diode helps shield

downstream electronics from

overvoltage and reverse bias

• Trip events shut out overvoltage and

reverse bias sources

• Analog nature of trip events minimizes

upstream inductive spikes

• Minimal power dissipation requirements

• Single component placement

TARGET APPLICATIONS

• DC power port protection in portable

electronics

• DC power port protection for systems

using

barrel jacks for power input

• Internal overvoltage & transient

suppression

• DC output voltage regulation