Axial lead fuse optimised for protecting wall-mounted chargers

The 777 Series is optimised for protecting wall-mounted chargers for smartphones and tablets that experience direct shors on an AC plug.

Michelle DiFrangia, Assistant Editor of Design World and Lee Teschler, Executive Editor of Design World discuss a smartphone charger which brings up the subject of when mobile phones were flip phones.

Teschler said the reason he mentions the flip phones is because chargers like the one seen in the video for smartphones are a larger wattage than the chargers for the older generation phones.

Why is that?
Basically because there’s more going on in a smartphone. The chargers for the more modern phones and tablets can hit 15 or 20W and they’re using higher currents than the older chargers simply because everyone wants fast charging.

Consequently, you’re likely to find a fuse in the input circuit in the smartphone charger.

Which brings us to the 777 Series fuse designed by Littelfuse, and specifically designed for chargers that provide higher wattage.

The important thing to remember about this device is that it needs to open up when there’s a short circuit but it also has to not open because of momentary charges or pulses which can happen in a normal operation for a variety of reasons.

DiFrangia then asked if that would be because of an electronic surge. Teschler went on to explain the I Triple E standard device for characterising these types of surges and that’s why Littelfuse designed this particular device to withstand up to 24 hits of a 7.5 killable ring wave surge as I Triple E defines it without opening.