Introduction to Littelfuse Mini Blade Fuses

Littelfuse is a global leader in circuit protection, and its Mini Blade Fuses (also known as small blade fuses or mini automotive fuses) are among the most widely used fuses in automotive electronics and low-voltage equipment. They are the compact successor to the standard ATO/ATC blade fuses, designed to save space while protecting the growing number of electronic modules in modern vehicles.

1. What is a Littelfuse Mini Blade Fuse?

A Littelfuse Mini Blade Fuse is a compact, plug-in type fuse that is significantly smaller than a standard ATO or ATC blade fuse (often called "regular" or "standard" size). Its primary advantage is its small footprint, allowing for higher circuit density in fuse boxes.

Key Features:

· Compact Size: Dimensions are approximately 10.9 mm x 3.81 mm x 8.73 mm, saving about 50% space compared to standard blade fuses.

· Plug-and-Play Design: Allows for easy insertion and removal from the corresponding fuse block, simplifying installation and replacement.
· Color-Coding: Uses an international standard color chart to identify its current rating, enabling quick visual identification.
· Transparent Housing: The plastic body is typically transparent, allowing for easy visual inspection of the fuse element to check if it has blown.
· High Performance: Available in various interrupting ratings (high and low) and blowing characteristics (fast-acting and time-delay) to suit different protection needs.

2. Main Series & Specifications

Littelfuse offers two primary series of Mini Blade fuses, which differ in their interrupting capacity (the maximum fault current they can safely stop):

1. Standard Interrupting Rating Series
· Model Number: Typically starts with MINI, e.g., MINI-20 (for 20A).
· Interrupting Rating: Can safely interrupt 1000A at rated voltage.
· Application: Suitable for protecting most automotive electronic circuits, such as audio systems, lighting, and power windows.
2. High Interrupting Rating Series
· Model Number: Typically starts with MINI-AMP, e.g., MINI-AMP-20.
· Interrupting Rating: Can safely interrupt 2000A at rated voltage.
· Application: Designed for critical applications with potential high fault currents (e.g., circuits connected directly to the battery), providing a higher level of safety.

The following Littelfuse product models all belong to the MINI Blade (series).

3. Color Coding & Current Ratings

This is the most critical information for identifying a Mini Blade fuse, adhering to the global standard:

Color Rated Current Littelfuse Model Example
Tan 5A MINI-5
Brown 7.5A MINI-7.5
Red 10A MINI-10
Blue 15A MINI-15
Yellow 20A MINI-20 / MINI-AMP-20
Natural (Clear White) 25A MINI-25 / MINI-AMP-25
Green 30A MINI-30

4. Fuse Characteristics (Blowing Profile)

Littelfuse provides two blowing characteristics to match different load types:

· Fast-Acting:
· Characteristics: Opens very quickly on overcurrents and short circuits. Sensitive to current spikes.
· Application: Protects sensitive electronic equipment like control modules, circuit boards, and LED lighting, which cannot withstand sustained overcurrent.
· Time-Delay (Slow-Blow):
· Characteristics: Can withstand temporary intrush currents (e.g., motor startup) without opening, but will blow under a continuous overload or short circuit.
· Application: Ideal for circuits with motors, solenoids, or capacitors, such as power window motors, windshield wipers, and fan motors.

Note: Time-delay fuses are often marked differently on the top or have distinct model numbers. Always check the specifications when selecting a replacement.

5. Primary Applications

· Automotive Industry (Primary Market): The fuse boxes of modern vehicles predominantly use Mini Blade fuses to protect body control modules, infotainment systems, airbags, lighting, and power accessories.
· Low-Voltage Industrial Equipment: DC power supplies, control systems, and communication equipment.
· Marine and Recreational Vehicles (RVs): 12V/24V DC electrical systems.
· Solar Power Systems: Branch circuit protection in solar combiner boxes and charge controllers.

6. How to Select and Replace

1. Determine the Rated Current: Refer to the equipment's manual or the rating on the original fuse. Never replace a fuse with one of a higher current rating, as this can lead to wire overheating and fire.
2. Select the Blowing Characteristic: Choose fast-acting or time-delay based on the load type. When in doubt, match the characteristic of the original fuse.
3. Check Voltage Rating: Littelfuse Mini Blade fuses are typically rated for 32VDC, making them suitable for 12V or 24V automotive and marine systems.
4. Replacement Procedure:
· Turn off the power to the circuit/device.
· Use a fuse puller tool (often found in the vehicle's fuse box lid) to remove the blown fuse.
· Visibly inspect the fuse to confirm the element inside is broken.
· Insert a new fuse of the exact same specification (same current rating and blowing characteristic).

7. Advantages of the Littelfuse Brand

· High Reliability: Stringent quality control and testing ensure stable performance in harsh environments (e.g., high temperature and vibration in engine compartments).
· Compliance with Standards: Products meet international safety standards like UL/CSA, CE, and are often AEC-Q200 qualified for automotive use.
· Global Recognition: As an industry benchmark, Littelfuse is specified as original equipment or service parts by major automotive manufacturers worldwide.

Summary

The Littelfuse Mini Blade Fuse is a miniaturized, high-performance, and highly reliable circuit protection component. It is an essential safety guardian in modern vehicles and low-voltage electrical systems. When selecting one, always pay close attention to its rated current (color), blowing characteristic (fast/time-delay), and interrupting rating to ensure precise and safe protection for your equipment.