The AO3401A (marked as A19T) is a high-density, low-threshold P-Channel enhancement mode field-effect transistor utilizing advanced trench MOSFET technology. Engineered to deliver ultra-low on-state resistance (R_DS(ON)), low gate charge, and fast switching speeds within an ultra-compact SOT-23 surface-mount package, it is ideally suited for high-side load switching, power distribution management, battery protection, and reverse polarity protection in compact, battery-powered electronic devices.

Specifications

• Brand / Manufacturer: Alpha & Omega Semiconductor (AOS)
• Part Number / Marking: AO3401A / A19T
• Transistor Type: P-Channel MOSFET
• Drain-Source Breakdown Voltage (V_DS): -30V
• Gate-Source Voltage (V_GS): ±12V
• Continuous Drain Current (I_D): -4.0A (at V_GS = -10V, T_A = 25°C) / -3.2A (at T_A = 70°C)
• Pulsed Drain Current (I_DM): -27A
• Low On-Resistance (R_DS(ON)): < 44m>GS = -10V (I_D = -4.0A)
• Low On-Resistance (R_DS(ON)): < 55m>GS = -4.5V (I_D = -3.5A)
• Low On-Resistance (R_DS(ON)): < 85m>GS = -2.5V (I_D = -2.0A)
• Gate Threshold Voltage (V_GS(th)): -0.5V to -1.3V (Typical -0.9V)
• Total Gate Charge (Q_g): Approx. 7nC (at V_GS = -4.5V) / 14nC (at V_GS = -10V)
• Maximum Power Dissipation (P_D): 1.4W (at T_A = 25°C)
• Operating Junction & Storage Temperature: -55°C to +150°C
• Package / Case: SOT-23 (TO-236) Surface Mount (Pin 1: Gate, Pin 2: Source, Pin 3: Drain)

Features

• Advanced Trench Power MOSFET Technology: Provides exceptionally low R_DS(ON) and gate charge to minimize conduction losses and thermal dissipation during high-current switching.
• Sub-Logic Level Gate Drive: Fully operational with gate voltages down to -2.5V, enabling direct high-side switching from 3.3V and 5V control circuits and microcontrollers.
• High-Side Switching Without Charge Pumps: As a P-Channel device, it simplifies high-side load switching without requiring an auxiliary bootstrap capacitor or charge pump circuit.
• High Current Handling in Miniature Footprint: Supports continuous load currents up to -4.0A in an industry-standard space-saving SOT-23 package.
• Fast Switching & Low Capacitance: Minimal gate capacitance facilitates rapid turn-on and turn-off transitions, reducing switching losses during PWM operation.

Common Applications

• High-Side Load Switching: Clean power rail gating for sub-circuits, peripheral sensors, and display modules in portable electronics.
• Reverse Battery / Polarity Protection: Efficient, ultra-low voltage drop alternative to standard series Schottky diodes in DC input stages.
• Power Management & Battery Disconnect: Regulating power distribution in smartphones, tablets, IoT boards, and wearable devices.
• DC-DC Converter & Inverter Circuits: Serving as the high-side pass transistor in step-down buck regulators and H-bridge drive networks.
• Relay & Solenoid Control: High-side drive switching for small actuators, valves, and indicators.

Usage Tips

• High-Side Gate Drive Configuration: Connect the Source (Pin 2) to the positive supply rail (V_IN) and the Drain (Pin 3) to the load. Pulling the Gate (Pin 1) to GND turns the MOSFET ON, while pulling it to V_IN turns it OFF.
• Pull-Up Resistor Recommendation: Always connect a 10kΩ to 100kΩ pull-up resistor between the Gate and Source pins to ensure the MOSFET remains securely in the OFF state during power-up or floating GPIO conditions.
• Level Shifting for Higher Supply Voltages: If switching supply voltages higher than your microcontroller GPIO voltage (e.g., 12V), use an external small-signal NPN transistor or N-Channel MOSFET (like the AO3400A) to pull the AO3401A Gate to GND.
• Gate Voltage Clamping: Ensure the Gate-to-Source differential voltage never exceeds the ±12V maximum limit; use a Zener diode across Gate and Source if operating near higher supply voltages.

Datasheet