onsemi BD13910STU NPN Power Transistor: Datasheet, Pinout, and Application Circuits
The BD13910STU from onsemi is a robust and widely used NPN power transistor housed in the versatile SOT-32 (also known as TO-126) package. Designed for medium-power linear and switching applications, this component is a staple in the toolkits of electronics designers and hobbyists alike. Its excellent DC current gain characteristics and high collector current capability make it suitable for a broad range of circuits, from audio amplification to motor control and voltage regulation.
This article provides a detailed overview of the BD13910STU, covering its key specifications from the datasheet, pinout configuration, and practical application circuits.
BD13910STU: Datasheet Overview and Key Specifications
The BD13910STU is part of the BD13x family, with the "10" suffix indicating a specific DC current gain (hFE) classification. Understanding its absolute maximum ratings and electrical characteristics is crucial for reliable circuit design.
Absolute Maximum Ratings (Ta = 25°C):
Collector-Emitter Voltage (VCEO): 80 V
Collector-Base Voltage (VCBO): 80 V
Emitter-Base Voltage (VEBO): 5 V
Continuous Collector Current (IC): 1.5 A
Collector Power Dissipation (Ptot): 12.5 W (at case temperature Tc = 25°C)
Junction and Storage Temperature (Tj, Tstg): -65 to +150 °C
Key Electrical Characteristics (Ta = 25°C):
DC Current Gain (hFE): Classified as 'L' (40~100) at IC = 150 mA, VCE = 2 V. The BD139-10 offers a typical gain of 100 to 250 under common operating conditions, providing good amplification.
Collector-Emitter Saturation Voltage (VCE(sat)): Typically 0.5 V (max. 1.0 V) at IC = 500 mA, IB = 50 mA. This low saturation voltage is key for efficient switching.
Transition Frequency (fT): 50 MHz (min.), indicating its usefulness in audio and other medium-frequency applications.
Thermal Characteristics:
Thermal Resistance, Junction-to-Case (RthJC): 10 °C/W
Effective heat sinking is essential when operating near the maximum power dissipation limits. The metal tab on the package allows for easy mounting to a heatsink.
BD13910STU Pinout Configuration
The BD13910STU package (SOT-32/TO-126) has three pins. When viewing the component from the front (the side with the markings), with the metal tab facing down and facing you, the pinout is as follows:
Pin 1 (Left): Emitter (E)
Pin 2 (Middle): Collector (C)
Pin 3 (Right): Base (B)
Always double-check the pinout with a multimeter in diode mode or the official datasheet before connecting it to a circuit to prevent damage.
Application Circuits
The BD13910STU is highly versatile. Here are two classic circuit examples:
1. Linear Amplifier (Class A Audio Stage):
The BD139 is an excellent choice for pre-amplifier or small headphone amplifier stages. In a simple common-emitter configuration, a small audio signal applied to the base (through a coupling capacitor) is amplified and appears at the collector. Proper biasing resistors (R1 and R2) set the transistor's operating point (quiescent point) in the linear region of its characteristic curve. An emitter resistor (Re) provides negative feedback for thermal stability, and a collector resistor (Rc) defines the voltage gain.
2. Low-Side Switch for Motor or Relay Drive:
A very common use for the BD139 is as a low-side switch. In this configuration, the load (e.g., a DC motor, relay, or lamp) is connected between the positive supply rail and the collector pin. The emitter is connected to ground.
A control signal from a microcontroller, logic IC, or switch is fed to the base through a current-limiting resistor (typically 1kΩ to 10kΩ). When the control signal is HIGH (e.g., 5V), the transistor is driven into saturation, acting as a closed switch and allowing current to flow through the load to ground. A flyback diode is critical when driving inductive loads like motors or relays to protect the transistor from voltage spikes generated when the current is suddenly switched off.
ICGOOODFIND: The onsemi BD13910STU remains a fundamental and highly reliable component for power management and amplification tasks. Its well-balanced specifications for voltage, current, and gain, combined with its easy-to-manage package, make it an ideal choice for designers seeking a robust solution for driving loads, amplifying signals, or general purpose switching. Its enduring popularity is a testament to its utility and performance across countless projects.
Keywords: NPN Transistor, Power Amplifier, Low-Side Switch, Saturation Voltage, Current Gain
