BFuse is an electronic fuse designed especially for breadboards. It is fast, adjustable and programmable.

Why BFuse

A lot of mistakes can happen during prototyping: Misplacing components, creating random shorts or simply making things wrong. BFuse can help saving precious components that would otherwise be damaged by such mistakes. It works like a regular fuse, only better :-)

1) It is faster: Load is disconnected within 200 microseconds after an overcurrent occurs.

2) It is resettable: Simply by pushing a button.

3) It is adjustable: By turning a trimmer, you can set the trip current anywhere between 50mA and 1A.

4) It is programmable: If you wish, you can adjust the behaviour of the fuse by programming its AVR ATTiny 25 microcontroller. But you don't have to, BFuse comes pre-programmed.

How does it work

BFuse constantly compares the load current with the value set by the trimmer. If an overcurrent occurs, it disconnects the load by switching off a P-channel MOSFET. It also notifies the user by lighting a red LED. A green LED indicates that the load is connected. Even though the fuse is designed for operations up to 1A, it can measure current up to 6A, giving you options to allow for some inrush current for capacitive loads. BFuse is powered by the same line it protects, no extra power needed.

More protection

BFuse not only protects against overcurrent but it has also built-in reverse polarity protection. Moreover, it has a transient-voltage suppressor on both its input and output. BFuse was tested on a 22-Amp Statron stabilized power source for short-circuit and startup into short-circuit – it passed with flying colours.

Technical parameters

• Input voltage range: 3.3–12V (absolute maximum rating 3–13V)
• Measured current range: 6A
• Trip current range: 50mA–1A
• Fuse resistance: less than 100 milliohm
• Fuse power consumption: less than 10mA
• Dimensions: 18×36mm
• Weight: 4.5 grams

Some assembly required

BFuse comes as a kit – you will have to solder the pin headers: 4 pins for the power line (input/output) and if you wish to re-program BFuse, then also 6 pins for the SPI header. All pin headers are supplied with BFuse.

Known limitations

BFuse cannot act as a current-limiter in linear mode. It means it is not suitable for highly capacitive loads with high-current-capable power supplies that exceed 6 Amps of inrush current.