Products >> Discrete semiconductor product >> Power transistors (BJT, JFET, MOSFET, IGBT）

Power transistors are semiconductor devices for handling high - power signals.

Bipolar Junction Transistor (BJT) controls the collector - emitter current through the base current. It has a high current gain and is suitable for low - frequency and high - power scenarios like audio power amplification, but its switching speed is relatively slow.Junction Field - Effect Transistor (JFET) uses an electric field to control the channel current. It has a high - input impedance and low noise, applicable for signal amplification and switching circuits, though its power - handling ability is limited.Metal - Oxide - Semiconductor Field - Effect Transistor (MOSFET) controls the source - drain current via the gate voltage. It has an extremely high - input impedance and fast - switching speed, used in high - frequency power applications and power management such as in computer motherboard power supplies.Insulated - Gate Bipolar Transistor (IGBT) combines the advantages of BJT and MOSFET. It has a high - input impedance, low - on - state voltage drop, and high - voltage - withstanding ability, often used in high - power industrial applications like motor control and inverters.

main parameters of power transistors?

Voltage Parameters
- Breakdown Voltages: These include Collector - Emitter Breakdown Voltage,Collector - Base Breakdown Voltage , and Emitter - Base Breakdown Voltage . These voltage values determine the maximum voltage limit that the power transistor can withstand. Exceeding these voltages may damage the transistor. For example, in a high - voltage power supply circuit, a power transistor with a high breakdown voltage needs to be selected.
Current Parameters
- Maximum Collector Current : It refers to the maximum current value that the collector of the power transistor can allow to pass through. In practical use, a certain margin is usually reserved, and generally only 1/3 to 1/2 of this value is used. Exceeding this current will cause the transistor to overheat and even be damaged.
- Saturation Current: The current between the collector and the emitter in the saturation state. For the application of power transistors in switching circuits, the saturation current is an important parameter that affects the switching performance of the transistor.
Power Parameters
- Maximum Power Dissipation : It refers to the power dissipation allowed by the power transistor at the highest operating temperature. The power transistor generates heat during operation. If the power dissipation exceeds this value, the transistor temperature will be too high and damaged. When this parameter is given in the product manual, the case temperature is usually given at the same time to indirectly indicate the highest operating temperature.
Frequency Parameters
- Transition Frequency : The frequency corresponding to when the current amplification factor of the transistor drops to 1. It reflects the amplification ability of the power transistor under high - frequency signals. For power transistors working in high - frequency circuits, the transition frequency is an important parameter.
Amplification Factor Parameters
- Current Amplification Factor : For bipolar power transistors, it is defined as the ratio of the collector current to the base current, reflecting the control ability of the base current on the collector current.
- Transconductance: For field - effect power transistors, transconductance is a parameter that measures the control ability of the gate voltage on the drain current, that is, the ratio of the change in the drain current to the change in the gate voltage.
Switching Time Parameters
- Turn - on Time : The time required from the control signal that starts the power transistor to conduct until it is fully conducting.
- Turn - off Time: The time required from the control signal that starts the power transistor to turn off until it is fully turned off. Switching time parameters are very important for the application of power transistors in high - frequency switching circuits and affect the working efficiency and performance of the circuit.
Inter - electrode Capacitance Parameters: These include Gate - Source Capacitance, Gate - Drain Capacitance and Drain - Source Capacitance. The inter - electrode capacitances affect the switching speed and high - frequency performance of the power transistor, and their effects need to be considered in high - frequency circuit design.
Maximum Allowable Junction Temperature， When the junction temperature of the power transistor is too high, it will lead to thermal breakdown and burnout. This parameter is the highest allowable junction temperature at which the power transistor can work normally.