IRLML2502 — N-Channel 20V Logic-Level Power MOSFET (SOT-23)

Overview

The IRLML2502 (IRLML2502TRPBF) is an N-channel logic-level HEXFET power MOSFET manufactured by Infineon Technologies (formerly International Rectifier). Housed in a subminiature SOT-23 (Micro3) surface-mount package, it provides exceptionally low on-resistance and high current capability from low gate drive voltages.

With a drain-source voltage rating of $20\text{ V}$ , continuous drain current of up to $4.2\text{ A}$ , and an $R_{DS(on)}$ of just $45\text{ m}\Omega$ at $V_{GS} = 4.5\text{V}$ (and $80\text{ m}\Omega$ at $2.5\text{V}$ ), the IRLML2502 is tailored for battery-powered IoT devices, Li-ion battery protection boards, high-side/low-side load switches, and small DC motor or solenoid actuators driven directly by 3.3V or 2.5V microcontrollers.

Quick reference


Transistor Type	N-Channel Logic-Level Enhancement Mode MOSFET
Package	SOT-23 (Micro3 / TO-236AB)
Drain-Source Voltage ( $V_{DSS}$ )	$20\text{ V}$ max
Continuous Drain Current ( $I_D$ )	$4.2\text{ A}$ at $V_{GS} = 4.5\text{V}$ ( $3.4\text{ A}$ at $70^\circ\text{C}$ )
Gate Threshold Voltage ( $V_{GS(th)}$ )	$0.6\text{ V}$ min to $1.2\text{ V}$ max
On-Resistance ( $R_{DS(on)}$ )	$45\text{ m}\Omega$ max at $4.5\text{V}$ / $80\text{ m}\Omega$ max at $2.5\text{V}$
Pulsed Drain Current ( $I_{DM}$ )	$33\text{ A}$
Total Power Dissipation ( $P_D$ )	$1.25\text{ W}$ at $T_A = 25^\circ\text{C}$ ( $0.8\text{ W}$ at $70^\circ\text{C}$ )

Terminal identification

Looking at the top of the SOT-23 package with the single top pin and two lower pins:

text

               ┌─────────┐
               │    3    │  (DRAIN)
               └─┐     ┌─┘
                 │ 2502  │
               ┌─┘     └─┐
               │ 1     2 │
               └─────────┘
             (GATE)   (SOURCE)

Pin	Terminal	Description
1	`GATE` (`G`)	Gate control input (Connect to MCU GPIO via series resistor)
2	`SOURCE` (`S`)	Source terminal (Connect to Ground 0 V)
3	`DRAIN` (`D`)	Drain terminal (Connect to load negative return)

Specifications

Parameter	Symbol	Min	Typ	Max	Unit	Conditions
Drain-Source Breakdown Voltage	$V_{(BR)DSS}$	20	—	—	V	$V_{GS} = 0\text{V}, I_D = 250\ \mu\text{A}$
Gate Threshold Voltage	$V_{GS(th)}$	0.6	—	1.2	V	$V_{DS} = V_{GS}, I_D = 250\ \mu\text{A}$
On-Resistance ( $V_{GS} = 4.5\text{V}$ )	$R_{DS(on)}$	—	35	45	mΩ	$V_{GS} = 4.5\text{V}, I_D = 4.2\text{A}$
On-Resistance ( $V_{GS} = 2.5\text{V}$ )	$R_{DS(on)}$	—	60	80	mΩ	$V_{GS} = 2.5\text{V}, I_D = 2.1\text{A}$
Total Gate Charge	$Q_g$	—	8.0	12.0	nC	$V_{GS} = 4.5\text{V}, V_{DS} = 16\text{V}, I_D = 4.2\text{A}$
Turn-On Delay Time	$t_{d(on)}$	—	6.4	—	ns	$V_{DD} = 10\text{V}, I_D = 1.0\text{A}, R_G = 6\ \Omega$
Turn-Off Delay Time	$t_{d(off)}$	—	31	—	ns	$V_{DD} = 10\text{V}, I_D = 1.0\text{A}, R_G = 6\ \Omega$

Typical circuits

Low-Side Load Switch (3.3V Microcontroller Control)

text

        +5V / +12V Power Rail
           │
         [ LOAD (LED Strip / DC Motor / Solenoid) ]
           │
           ├─── [ Flyback Diode 1N4148 / 1N4001 across inductive load ]
           │
        [Pin 3: DRAIN]
         IRLML2502
        [Pin 2: SOURCE] ─── GND
           │
        [Pin 1: GATE] ◄───[ R_gate = 100Ω ]───◄ MCU GPIO (3.3V / 5V)
           │
        [ R_pulldown = 100kΩ ]
           │
          GND

Selection & substitutes

Part Number	Package	$V_{DSS}$	$I_D$	$R_{DS(on)}$ at 4.5V	Notes
IRLML2502	SOT-23	$20\text{ V}$	$4.2\text{ A}$	$45\text{ m}\Omega$	Low gate threshold, high efficiency
AO3400A	SOT-23	$30\text{ V}$	$5.7\text{ A}$	$33\text{ m}\Omega$	Higher voltage and current rating
BSS138	SOT-23	$50\text{ V}$	$0.22\text{ A}$	$3.5\ \Omega$	Signal switching & I2C level shifter only

Common mistakes

Exceeding the $\pm 12\text{V}$ Gate-Source limit ( $V_{GS}$ ): Standard power MOSFETs tolerate $\pm 20\text{V}$ on the gate, but the subminiature gate oxide of the IRLML2502 has an absolute maximum rating of $\pm 12\text{V}$ . Never connect the gate directly to $15\text{V}$ or $24\text{V}$ supplies without a voltage divider or Zener clamp.
Missing gate pull-down resistor: During MCU boot/reset, GPIO pins default to high-impedance inputs. Without a $100\text{ k}\Omega$ pull-down resistor to ground, static charge on the gate will cause the MOSFET to partially turn ON.
Ignoring PCB thermal copper dissipation: While rated for $4.2\text{ A}$ , maintaining continuous currents $> 2.5\text{ A}$ in a tiny SOT-23 package requires adequate PCB copper pour attached to Pin 3 (DRAIN) to prevent overheating ( $R_{\theta JA} = 100^\circ\text{C/W}$ ).

Notes

Suffix Identification: The standard lead-free production part number is IRLML2502TRPBF (supplied on tape and reel).