The IRLML6401 from Infineon (originally International Rectifier) is a P-channel power MOSFET in the industry-standard SOT-23 (Micro3) surface-mount package. The IRLML6401TRPBF is the tape-and-reel, Pb-free, halogen-free version. It is one of the most popular P-channel MOSFETs for low-voltage load switching applications, with extensive multi-source availability.
The -12 V drain-source rating and -4.3 A continuous current capability make it ideal for Li-ion battery-powered applications where a high-side P-channel switch is needed. The 50 mΩ maximum RDS(on) at VGS = -4.5 V results in only 215 mW of conduction loss at 4.3 A, well within the 1.3 W package rating with modest PCB copper area.
The low threshold voltage (VGS(th) = -0.55 V typical, -1.0 V maximum) allows the IRLML6401 to be driven directly from 1.8 V logic. At VGS = -2.5 V, RDS(on) increases to approximately 80-90 mΩ but remains usable for moderate current loads, making 1.8 V/2.5 V GPIO-driven load switches practical.
The 10 nC total gate charge enables switching frequencies up to several hundred kHz with minimal gate-drive loss, suitable for DC-DC converter applications where a P-channel high-side switch is preferred over a bootstrap-driven N-channel.
The SOT-23 package provides RθJA of approximately 75-100°C/W depending on PCB layout. With the large drain tab soldered to a copper pour with thermal vias, the device can handle its full rated current in continuous operation.
Note: Infineon has designated the IRLML6401TRPBF-1 as discontinued (replaced by IRLML6401TRPBF). However, the device remains widely available from distributors with over 139K units in stock at Farnell alone. Multiple second-source manufacturers (VBsemi, Kexin, Born) produce compatible versions.