100V MOSFETs designed as a switch for 48V PoE

In power-sourcing equipment such as LAN routers and midspans, the N-channel MOSFET switches power to the CAT5 (or CAT6) network cable. The cable then provides both power and data, which reduces system costs by eliminating the power supply in the end-equipment. It also protects end-users because PoE operates between 44 to 57V, which meets the 60V safety extra low voltage rating, removing the need for rigorous isolation and certification of end-equipment while also easing system maintenance. I2R losses are minimised when operating at these voltage levels and this helps maximise power delivery to the end-equipment and improve efficiency.

With a 100V BVDSS rating the DMN10H120SFG MOSFET provides plenty of headroom for 48V PoE operation. The DMN10H120SFG also offers an extended safe-operating-area that can withstand the power dissipation due to short-circuit fault conditions, such as an Ethernet cable breaking, until the PSE controller detects the fault and switches off. During this fault condition the MOSFET goes into linear mode and needs to dissipate 30W for at least 20ms, which is achieved even with a +60°C elevated operating temperature.

The DMN10H120SFG is offered in the space-saving PowerDI3333 package. Within its extensive 100V DMN10H family, Diodes also offers SOT23, SOT223 and TO252 (DPAK) packages. The avalanche-rugged DMN10H099SK3, for example, in TO252 is 100% unclamped-inductive-switch tested to ensure it can withstand the energy pulse in switching inductive loads such as coils, motors and relays.

Pricing for the DMN10H series MOSFETs ranges from $0.12-0.30 each, dependent on specification and package type, in 10,000 unit quantities.