Bel Fuse 0ZSC0380FF1E

Fundamentally, a Bel PTC consists of a block of polymeric material containing conductive filler, bonded between two conductive planar terminals. At currents below the device's IHOLD rating and at temperatures below 100°C, the PTC maintains a resistance below its R1 MAX rating. As the device temperature approaches 130°C — whether due to elevated ambient temperature or current exceeding its I TRIP rating — the volumetric expansion of the filled polymer disrupts most of the conductive pathways formed by the chain-contact of adjacent filler particles between the terminals, causing device resistance to increase sharply by several orders of magnitude. At this higher "tripped" resistance, only sufficient leakage current flows to sustain internal heating, keeping the device in the tripped state (approximately 125°C) until power is interrupted. Once power is removed, the PTC's core cools and contracts, allowing the conductive chains to re-form and returning the device to its low-resistance state. The catalog data for each device specifies a "typical power" value. This is the power required at 23°C for a tripped device to dissipate heat to the surrounding environment in thermal equilibrium. By Ohm's Law, power can be expressed as: W = E² / R. Therefore, the approximate resistance of a "tripped" PTC can be determined by: R = E² / W, where "E" is the voltage across the PTC (typically the open-circuit voltage of the supply) and "W" is the typical power value for the specific PTC. Since the function of a PPTC is to maintain a constant internal temperature, its apparent resistance will vary with applied voltage and, to a lesser extent, with ambient conditions.

• Low profile
• Low resistance
• High hold current
• Solid state
• Operating (hold current) range: 1.9A - 7.3A
• Maximum voltage: 20VDC
• Temperature range: -40°C ~ 85°C
• Agency approvals: TUV (standard EN60738-1-1, certificate R50102187), UL component (standard UL1434, file E305051)

• Rechargeable battery packs
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