The SI2301 (marked as A1SHB) is a high-density, sub-logic level P-Channel enhancement mode field-effect transistor utilizing advanced trench MOSFET technology. Designed to deliver low on-state resistance (R_DS(ON)), fast switching speeds, and low gate drive capability within an ultra-compact SOT-23 surface-mount package, it is ideally suited for high-side load switching, power distribution management, battery disconnect circuits, and reverse polarity protection in portable battery-powered electronics.

Specifications

• Brand / Manufacturer: Vishay Siliconix / Industry Standard
• Part Number / Marking: SI2301 / SI2301CDS / A1SHB
• Transistor Type: P-Channel MOSFET
• Drain-Source Breakdown Voltage (V_DS): -20V
• Gate-Source Voltage (V_GS): ±8V (Up to ±12V depending on manufacturer grade)
• Continuous Drain Current (I_D): -2.8A (at V_GS = -4.5V, T_A = 25°C) / -2.3A (at V_GS = -2.5V)
• Pulsed Drain Current (I_DM): -10A
• Low On-Resistance (R_DS(ON)): < 90m>GS = -4.5V (I_D = -2.8A)
• Low On-Resistance (R_DS(ON)): < 130m>GS = -2.5V (I_D = -2.0A)
• Gate Threshold Voltage (V_GS(th)): -0.45V to -1.0V (Typical -0.7V)
• Total Gate Charge (Q_g): Approx. 4.5nC (at V_GS = -4.5V)
• Maximum Power Dissipation (P_D): 1.25W (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 TrenchFET Technology: Delivers high cell density and low on-resistance to minimize power dissipation and heat generation during conduction.
• Sub-Logic Level Gate Drive: Operates efficiently with low gate voltages down to -2.5V, enabling direct high-side drive from 3.3V and 5V microcontrollers and low-voltage logic circuitry.
• Simplified High-Side Switching: As a P-Channel device, it enables direct load gating on the positive rail without requiring an external charge pump or bootstrap circuit.
• Compact SOT-23 Footprint: Provides high power handling and reliable thermal dissipation in a miniature surface-mount package, saving valuable PCB area.
• Fast Switching Speed: Low gate-to-drain charge ensures quick turn-on and turn-off transitions, minimizing switching losses in PWM power management circuits.

Common Applications

• High-Side Power Rail Switches: Gating sub-circuits, peripheral sensors, and wireless communication modules in portable electronics.
• Battery Disconnect & Charging Circuits: Regulating charge paths and battery isolation in lithium-ion and multi-cell battery packs.
• Reverse Polarity Protection: Low-forward-drop protection on DC input rails as an efficient alternative to traditional Schottky diodes.
• DC-DC Converters & Inverters: High-side switching stages in compact buck and boost power topologies.
• Small Actuator & Indicator Drivers: High-side switching for relays, indicator LEDs, solenoids, and buzzers.

Usage Tips

• High-Side Connection: Connect the Source (Pin 2) directly to the positive input voltage rail (V_IN) and the Drain (Pin 3) to the load. Pull the Gate (Pin 1) to GND to turn the MOSFET ON, and pull it high to V_IN to turn it OFF.
• Pull-Up Resistor Placement: Always install a 10kΩ to 100kΩ pull-up resistor between the Gate and Source pins to prevent floating gate states and unwanted turn-on during microcontroller startup.
• Gate Voltage Limit Compliance: Ensure that the Gate-to-Source differential voltage (V_GS) remains strictly within the rated ±8V limit. If switching supply voltages above 5V, use a resistor divider or Zener diode clamp on the Gate.
• Flyback Suppression: When driving inductive loads such as relays or DC motors, place a fast-recovery freewheeling diode (e.g., Schottky diode) across the load to protect the MOSFET against inductive kickback spikes exceeding V_DS.

Datasheet