DMG2305UX — -20V -4.2A Ultra-Low On-Resistance P-Channel MOSFET (SOT-23)

Overview

The DMG2305UX (DMG2305UX-7) is a -20V -4.2A ultra-low on-resistance P-channel logic-level power MOSFET manufactured by Diodes Incorporated. Housed in a compact SOT-23 surface-mount package, it is specifically engineered for ultra-low-voltage gate drive applications.

Featuring guaranteed on-resistance specifications down to $V_{GS} = -1.5\text{V}$ ( $125\text{ m}\Omega$ ), $V_{GS} = -1.8\text{V}$ ( $82\text{ m}\Omega$ ), and just $41\text{ m}\Omega$ at $V_{GS} = -4.5\text{V}$ , the DMG2305UX delivers high current conduction even when driven by low-voltage $1.8\text{V}$ microcontroller GPIOs or single-cell lithium chemistry nearing complete depletion ( $3.0\text{V}$ ). It is standard equipment in wearable electronics, IoT sensor nodes, smartphone power management, USB Type-C load switches, and battery reverse-polarity protection circuits.

Quick reference


Transistor Type	P-Channel Sub-1.8V Logic-Level MOSFET
Package	SOT-23 (3-pin SMD)
Drain-Source Breakdown Voltage ( $V_{DSS}$ )	$-20\text{ V}$ max
Gate-Source Voltage ( $V_{GSS}$ )	$\pm 8\text{ V}$ max
Continuous Drain Current ( $I_D$ )	$-4.2\text{ A}$ ( $T_A = 25^\circ\text{C}$ ) / $-3.3\text{ A}$ ( $T_A = 70^\circ\text{C}$ )
Pulsed Drain Current ( $I_{DM}$ )	$-25\text{ A}$
On-Resistance ( $R_{DS(on)}$ at $-4.5\text{V}$ )	$41\text{ m}\Omega$ max ( $32\text{ m}\Omega$ typ)
On-Resistance ( $R_{DS(on)}$ at $-2.5\text{V}$ )	$55\text{ m}\Omega$ max ( $41\text{ m}\Omega$ typ)
On-Resistance ( $R_{DS(on)}$ at $-1.8\text{V}$ )	$82\text{ m}\Omega$ max ( $55\text{ m}\Omega$ typ)
On-Resistance ( $R_{DS(on)}$ at $-1.5\text{V}$ )	$125\text{ m}\Omega$ max ( $70\text{ m}\Omega$ typ)
Gate Threshold Voltage ( $V_{GS(th)}$ )	$-0.4\text{ V}$ to $-1.0\text{ V}$ (Sub-1.8V Logic Compatible)
Power Dissipation ( $P_D$ )	$0.9\text{ W} \dots 1.4\text{ W}$

Pinout (SOT-23 Package)

Looking at the top of the SOT-23 package:

text

           ┌───┴───┐
           │   3   │ ── Pin 3: DRAIN (D)
           │       │
           │ 2305  │
           └──┬─┬──┘
              1 2
       Pin 1: GATE (G)
       Pin 2: SOURCE (S)

Pin	Name	Type	Description
1	`GATE (G)`	Control Input	Gate terminal (Driven LOW relative to Source to turn ON)
2	`SOURCE (S)`	Power Terminal	Source terminal (Connected to positive supply rail / Li-ion battery)
3	`DRAIN (D)`	Power Terminal	Drain terminal (Connected to switched DC load)

Specifications

Parameter	Symbol	Min	Typ	Max	Unit	Conditions
Drain-Source Breakdown	$V_{(BR)DSS}$	-20	—	—	V	$I_D = -250\ \mu\text{A}, V_{GS} = 0\text{V}$
Gate Threshold Voltage	$V_{GS(th)}$	-0.4	-0.65	-1.0	V	$V_{DS} = V_{GS}, I_D = -250\ \mu\text{A}$
Zero Gate Voltage Drain Current	$I_{DSS}$	—	—	-1.0	µA	$V_{DS} = -16\text{V}, V_{GS} = 0\text{V}$
Gate-Body Leakage Current	$I_{GSS}$	—	—	$\pm 100$	nA	$V_{GS} = \pm 8\text{V}, V_{DS} = 0\text{V}$
Static Drain-Source On-Resistance	$R_{DS(on)}$	—	32	41	mΩ	$V_{GS} = -4.5\text{V}, I_D = -4.2\text{A}$
Static Drain-Source On-Resistance	$R_{DS(on)}$	—	41	55	mΩ	$V_{GS} = -2.5\text{V}, I_D = -3.3\text{A}$
Static Drain-Source On-Resistance	$R_{DS(on)}$	—	55	82	mΩ	$V_{GS} = -1.8\text{V}, I_D = -2.0\text{A}$
Static Drain-Source On-Resistance	$R_{DS(on)}$	—	70	125	mΩ	$V_{GS} = -1.5\text{V}, I_D = -1.0\text{A}$
Total Gate Charge	$Q_g$	—	6.0	9.0	nC	$V_{GS} = -4.5\text{V}, V_{DS} = -10\text{V}, I_D = -4.2\text{A}$

Typical Application Circuit: 1.8V/3.3V High-Side Load Switch with N-Channel Driver

text

  +3.3V / +1.8V Power Rail ───────────────────────┬─────────► [Pin 2: SOURCE]
                                                  │              DMG2305UX
                                          [ 100kΩ Pull-Up ]      [Pin 3: DRAIN] ──► Switched Power to Sensor
                                                  │                 │
                                                  ├─────────► [Pin 1: GATE]
                                                  │
                                            [ DRAIN (D) ]
  MCU GPIO (1.8V / 3.3V) ───[ 1kΩ ]───► Gate of 2N7002 / AO3400 (N-Channel)
                                            [ SOURCE (S) ]
                                                  │
  System Ground (0V) ─────────────────────────────┴───────────────────────────────► Ground

Comparison: DMG2305UX vs AO3401A

Parameter	DMG2305UX	AO3401A
$V_{DSS}$ Breakdown	$-20\text{ V}$	$-30\text{ V}$
Max $V_{GS}$ Rating	$\pm 8\text{ V}$	$\pm 12\text{ V}$
$R_{DS(on)}$ at $-4.5\text{V}$	$41\text{ m}\Omega$	$55\text{ m}\Omega$
$R_{DS(on)}$ at $-1.8\text{V}$	$82\text{ m}\Omega$ (Guaranteed)	Unspecified
Ideal Application	$1.8\text{V}$ wearable / IoT power	$5\text{V}/12\text{V}$ general load switch

Common mistakes

Exceeding the $\pm 8\text{V}$ gate voltage limit: The ultra-thin gate oxide that allows $1.5\text{V}$ operation has a strict maximum breakdown rating of $\pm 8\text{V}$ . Connecting the gate to a $12\text{V}$ supply will permanently puncture the gate dielectric.
Operating without a gate pull-up resistor: In high-side switching circuits, an open microcontroller GPIO pin during boot-up or deep sleep will leave the gate floating, causing the MOSFET to partially conduct and overheat. Always include a $10\text{k}\Omega \dots 100\text{k}\Omega$ pull-up resistor between Gate (Pin 1) and Source (Pin 2).

Notes

Top Marking Code: The DMG2305UX package is marked with top marking code 25U or 25D.

Interface	Sub-1.5V to 8V Gate Drive Compatible
Package	SOT-23 (3-pin SMD)