IRF540NPBF

The IRF540NPBF from Infineon Technologies (formerly International Rectifier) is one of the most widely used N-channel power MOSFETs in the 100V class. With 44mΩ on-resistance at VGS=10V and 33A continuous drain current, it offers an excellent balance of voltage rating, current handling, and low conduction loss. The HEXFET (HEXagonal FET) architecture uses a hexagonal cell layout to maximize the channel width per unit silicon area, achieving low RDS(on) in a compact die. The 100V drain-source rating provides comfortable headroom for 12V, 24V, and 48V systems, where transients and inductive spikes can momentarily exceed the nominal supply. The gate threshold voltage of 2-4V means the device begins to turn on at logic levels but requires 10V for full enhancement (minimum RDS(on)). For 5V logic-level drive, the IRLZ44N (logic-level version) is preferred. The PBF suffix denotes the lead-free (Pb-free) version. The device is fully avalanche rated, meaning it can survive unclamped inductive switching events up to 185mJ without damage.

The IRF540NPBF is an N-channel enhancement-mode MOSFET. When VGS exceeds the threshold (2-4V), an inversion layer forms beneath the gate oxide, creating a conductive channel between drain and source. The channel resistance (RDS(on)) decreases as VGS increases: at VGS=4.5V, RDS(on) is typically 70-80mΩ; at VGS=10V, it drops to 44mΩ. For minimum conduction loss, VGS should be 10V or higher. When VGS falls below the threshold, the channel disappears and the MOSFET is OFF, blocking up to 100V between drain and source. The internal body diode (from source to drain) conducts when VDS goes negative, which is useful in half-bridge and H-bridge configurations where the diode carries current during the dead time between switching. However, the body diode is relatively slow (trr=170ns), which can cause losses in high-frequency switching applications. The 71nC total gate charge means the gate driver must supply this charge during turn-on and absorb it during turn-off; a gate driver capable of 1A can switch the MOSFET in approximately 70ns. The turn-on delay (11ns) plus rise time (35ns) give a total turn-on time of ~46ns; turn-off delay (39ns) plus fall time (35ns) give ~74ns turn-off time. For switching frequencies above 100kHz, these transition times contribute significant switching losses, and a MOSFET with lower Qg may be more appropriate.

IRF540NPBF pin assignment (TO-220-3, front view, pins down): Pin 1 (left) = Gate, Pin 2 (center) = Drain/Tab, Pin 3 (right) = Source. The tab is connected to Drain (Pin 2). For high-current applications, mount on heatsink with thermal compound. At ID=20A and VGS=10V, power dissipation can reach 2.5W from RDS(on) alone. For logic-level gate drive (5V), consider IRL540N which is optimized for 5V VGS operation.

• Low-Side Switch: Source=GND; Gate from MCU through gate driver (10V); Drain to load; 12V/24V motor, heater, or lamp control
• H-Bridge Motor: 4× IRF540N; 2 high-side + 2 low-side; 10V gate drive; bidirectional DC motor control
• Buck Converter: IRF540N as high-side switch; 100kHz max; Schottky freewheel diode; 12V to 5V at 10A
• Audio Amp: IRF540N in push-pull Class-D output; 100V rating for ±48V rails; gate driver for PWM input
• Solar Controller: IRF540N as series pass element; PWM controls charge current; 100V rating for 48V battery banks

IRF540NPBF is a 100V/33A N-channel MOSFET from Infineon in TO-220 with 44mΩ RDS(on). The IRL540N provides logic-level 100V/28A for 5V gate drive. The IRF540ZPBF offers lower 23mΩ in the same package. The FQP30N06L provides 60V/30A with 35mΩ and logic-level drive from onsemi. The IRF640N offers 200V/18A for higher voltage applications. For surface-mount, IRF540NSPBF provides the same in D2PAK. The STD70N02 from ST offers 24V/70A with 7.5mΩ for low-voltage high-current switching.