1808 SMD Fast Blow Fuse 125V – 5A

1808 SMD Fast Blow Fuse 125V 5A is a high-performance surface-mount circuit protection device designed to safeguard sensitive electronic components against overcurrent conditions. This compact fuse utilizes a fast-acting ceramic body construction, ensuring a rapid disconnect when current exceeds the rated threshold. Consequently, it prevents expensive downstream damage in high-density power supplies and communication equipment. The 1808 footprint offers a perfect balance between power handling and space efficiency for modern PCB layouts. Furthermore, its robust 125V rating makes it suitable for both AC and DC primary circuit protection. Therefore, you should specify this fast-blow fuse whenever your design requires reliable, rapid-response interruption in a small surface-mount package.

Key Features:

• Fast-Acting Response: This fuse provides rapid interruption of excessive current, which is critical for protecting delicate semiconductor devices.
• High Interrupting Rating: It safely breaks the circuit even under significant short-circuit conditions without physical rupture.
• Surface Mount Design: The 1808 (4512 Metric) package supports automated SMT assembly, reducing production costs and saving board space.
• Ceramic Body Construction: The inorganic ceramic housing offers excellent thermal stability and insulation during high-current clearing events.
• Wide Temperature Range: It operates reliably across a broad thermal spectrum, making it ideal for industrial and automotive environments.

Technical Specifications:

• Current Rating: 5 A
• Voltage Rating: 125 V (AC/DC)
• Fuse Type: Fast Acting / Fast Blow
• Interrupting Rating: 50 A @ 125 V_AC/DC
• Nominal Cold Resistance: ≈ 0.015 Ω
• Operating Temperature: −55°C to +125°C
• Melting Integral (I²t): ≈ 4.5 A²s

Mechanical Specifications:

• Package Code: 1808 (Imperial) / 4512 (Metric)
• Body Material: Advanced Ceramic
• Termination Material: Silver-plated caps with a Tin (Sn) overcoat
• Soldering Method: Compatible with Reflow and Wave soldering processes

Dimensions:

• Length: ≈ 4.50 mm (±0.2 mm)
• Width: ≈ 1.25 mm (±0.2 mm)
• Height: ≈ 1.25 mm (±0.2 mm)
• Termination Width: ≈ 0.50 mm

Pinout and Wiring:

• Polarity: This fuse is a non-polarized component; therefore, you can install it in either direction on the PCB pads.
• Connection: Place the fuse in series with the positive or “hot” line of the power input to ensure total isolation during a fault.
• Pad Layout: Ensure the PCB footprint matches the 1808 standard to maintain proper creepage and clearance distances for 125V operation.

Datasheet Reference:

• Download Littelfuse 451 Series (1808) Datasheet

Commonly Used in:

• Power Adapters: Serving as the primary protection stage for AC/DC wall chargers and laptop power bricks.
• Backlight Inverters: Protecting the high-voltage circuitry in LCD and LED display panels.
• Telecom Equipment: Shielding line cards and networking hardware from localized power surges.

Applications:

• Battery Management Systems: Preventing thermal runaway in Li-ion packs by interrupting short-circuit currents.
• Industrial Controllers: Protecting PLC inputs and outputs from wiring errors or component failures.
• Server Motherboards: Managing secondary rail protection in high-availability computing environments.

Equivalent Models:

• Littelfuse 0451005.MRL: A direct industry standard for the 1808 5A fast-acting SMD fuse.
• Bussmann 6125FA5A: A functional equivalent from Eaton, however, always verify specific dimensions before substitution.
• Bourns SF-1206F500: A similar fast-blow alternative, though it uses a smaller 1206 footprint.

Package Includes:

• 1 x 1808 SMD Fast Blow Fuse 125V 5A