Overcurrent Protection Solutions

Fuses

Fuses have been referred to as “one time” devices, in that the fuse will provide protection from the overload by opening only once and then need to be replaced. The heart of a typical fuse is a length of wire that is heated to its melting point by the excessive current. The circuit current flow decreases to zero as the wire melts open.

Benefits

• It is the most cost-effective form of protection • Operation of a fuse is simple, and no complexity is involved • A fuse’s inverse time current characteristic allows it to be used for overload protection

Applications

• Fuses completely stop current in fault condition; this may be more desired if safety or avoidance of downstream circuit equipment is a premium concern • Fuses are also helpful for diagnostic purposes, aiding equipment designers and users in tracing the origin of the overcurrent faults

PolySwitch ® PPTC Devices

PolySwitch Polymer Positive Temperature Coefficient (PPTC) devices offer a resettable overcurrent protection alternative, thereby reducing warranty, service, and repair costs. PPTCs increase resistance as temperature increases due to increased flow. The components are designed to limit unsafe currents while allowing constant safe current levels. Resistance will "reset" automatically when the fault is removed and temperature returns to safe levels. The ability of the PPTCs to reset themselves after exposure to a fault current makes them ideal within circuits that are not easily accessible. PPTCs are typically used as circuit protection in applications where sensitive components are at constant risk of damage from overcurrent conditions. The components are also ideal for situations where frequent overcurrent conditions occur or constant uptime is required.

Benefits

• Improved system reliability • Lower warranty cost and service • Reduced system downtime • Lower voltage drop • Ruggedness prevents breakage during manufacturing and shipment • Shock & vibration resistance eliminates need for calibration

Applications

• Port protection on personal computers (USB, firewire, keyboard/ mouse, and serial ports) • Peripherals (hard drives, video cards, and hubs) • Cell phones • Battery packs • Industrial controls • Lighting ballast • Motor controls