Increased safety and longer battery life for standalone devices
The range of battery-powered devices extends from powerful hand tools for craftsmen, to sensors for room surveillance through to life-saving medical aids. To ensure the safe operation of standalone devices, SCHURTER offers two SMD fuses with low power dissipation and very accurate tripping time. These days, battery-powered devices can be found everywhere. Although these handy assistants are very useful, any such device can catch fire, or an overcurrent condition can damage electronic circuits. For example, in medical technology even a brief malfunction could place a patient’s health at risk. When it comes to safety technology, a short reaction time is important in the event of faults, along with reliability across a wide temperature range. Both requirements have to be assured during the device’s overall service life. Furthermore, the following typical design parameters of standalone devices must be considered: Low power consumption, small form factor and an attractive price/performance ratio.
overcurrent ProtectIon In principle, overcurrent protection can also be implemented with an active protection circuitry. But a fuse, in particular an SMD fuse, is clearly more reliable and uses little space at low cost. In terms of power dissipation and tripping time, there is a clear difference among the various fuses available on the market. As for all these aspects, both the USF 0402 and USFF 1206 SMD fuses from SCHURTER feature values that make them a perfect solution for overcurrent protection of battery-driven devices.
Power dIssIPatIon
The power dissipation, caused by the impedance of the fuse, shall be as low as possible to ensure long operating time of battery-powered devices. The voltage drop of the USFF 1206 is < 95 mV and for the USF 0402 < 70 mV. These typical voltage drops at rated current are much lower than for any other comparable fuse on the market. The benefit of this low power dissipation is achieved by the unique design of these two fuse types. The melting wire is wire-bonded. It is just a few micrometers thick and made of a special alloy. In the case of the USF 0402, the melting wire is encapsulated in a special epoxy resin; on the USFF 1206 it is surrounded by air. Both technologies inhibit the dissipation of heat and thus reduce power
dissipation.
narrow wIndow of trIPPIng tIMe The USF 0402 and the USFF 1206 are designed according to the component standard UL 248-14. This standard defines a tripping time between 10 and 100 milliseconds. With a given tripping time of 70 milliseconds, the fuse is tripping between 60 and 80 milliseconds. The USF 0402 and USFF 1206 are currently the only available
blood glucose meter
super-Quick-acting sMd fuse usff 1206, 3.2 × 1.6 mm, ampere rating from 160ma to 250ma
UL 248-14
0 t [ms]
10 20 30 40 50 60 70 80 90 100
USF 0402 USFF 1206
fuses in this dimension that trip with such high precision.
super-Quick-acting sMd fuse usf 0402, 1.05 × 0.55 mm, ampere rating from 375ma to 5a
focus magazine - issue 9 11
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