BD136 Transistor (PNP, 45V, 1.5A)

Description

BD136 Transistor (PNP, 45V, 1.5A)

The BD136 is a PNP bipolar junction transistor (BJT) designed for switching and amplification applications. It is part of the BD13x series of power transistors, which are commonly used in medium-power circuits. The BD136 specifically offers a 45V maximum collector-emitter voltage and 1.5A maximum collector current, making it suitable for controlling loads and amplifying signals in various electronic circuits.

Key Features:

1. Type:
   • The BD136 is a PNP transistor, meaning it has a positive (P) type material between two negative (N) type materials. In a PNP transistor, current flows from the emitter to the collector when it is switched on.
2. Collector-Emitter Voltage (Vceo):
   • The BD136 has a maximum collector-emitter voltage of 45V, making it suitable for low- to medium-voltage circuits where voltages do not exceed this rating.
3. Collector Current (Ic):
   • The BD136 can handle a maximum collector current of 1.5A, making it useful for driving moderate loads such as relays, small motors, and LEDs.
4. Power Dissipation:
   • The BD136 can dissipate up to 30W of power, allowing it to handle significant amounts of heat in medium-power applications.
5. DC Current Gain (hFE):
   • The BD136 has a DC current gain (hFE) typically between 40 and 320, depending on the operating conditions, which is a measure of the transistor’s ability to amplify current.
6. Package Type:
   • The BD136 is usually available in a TO-220 package, which is designed for through-hole mounting and provides efficient heat dissipation in higher power applications.
7. Transition Frequency (ft):
   • The BD136 has a transition frequency (ft) of 250 MHz, which makes it suitable for use in audio, signal processing, and low-frequency RF circuits.

Applications:

1. Switching Applications:
   • The BD136 is commonly used in switching circuits to control loads such as motors, relays, and LEDs. It can be used in low- and medium-power motor control circuits, as well as for driving high-power LEDs.
2. Amplifier Circuits:
   • The BD136 is frequently used in audio amplifier circuits to provide signal amplification. It can be employed in class AB amplifiers, where it is often used for driving the output stage.
3. Power Amplifiers:
   • The transistor can be used in audio power amplifiers to drive speakers or other output devices. It helps boost the signal to a higher power suitable for powering loudspeakers or other actuators.
4. Voltage Regulators:
   • The BD136 is useful in voltage regulator circuits for regulating the output voltage in power supplies. It is often part of linear voltage regulators, where it helps maintain a stable output voltage despite changes in input voltage or load.
5. Relay Drivers:
   • It is often used to drive relays in control systems, especially in circuits requiring moderate current handling capabilities for controlling high-power loads via low-power control signals.
6. LED Drivers:
   • The BD136 can drive high-power LEDs in lighting circuits, especially in cases where the voltage and current requirements are higher than what a logic-level output can supply.
7. Switch Mode Power Supplies (SMPS):
   • The BD136 can be used in SMPS designs, providing switching functionality within the power conversion stages.

Advantages:

1. Medium Power Handling:
   • The BD136 can handle moderate current and voltage (up to 1.5A and 45V), making it ideal for medium-power circuits such as relay drivers, motor controllers, and low-power amplifiers.
2. Good Amplification Characteristics:
   • With its DC current gain in the range of 40 to 320, the BD136 is useful for low-power signal amplification in audio and analog circuits.
3. Low Cost and Availability:
   • The BD136 is widely available, inexpensive, and commonly used in many electronic applications, making it a good choice for hobbyists and professional engineers alike.
4. Efficient Power Dissipation:
   • With a maximum power dissipation of 30W, the BD136 is capable of handling moderate heat in medium-power circuits, making it a reliable option for various applications.

Disadvantages:

1. Limited Current Handling:
   • The 1.5A collector current rating limits its use in high-current applications. For more demanding circuits that require higher current handling, you may need to choose a transistor with a higher current rating.
2. Limited Voltage Rating:
   • With a 45V collector-emitter voltage rating, the BD136 is not suitable for high-voltage applications. For circuits requiring higher voltage tolerance, you should look for a transistor with a higher voltage rating.
3. Switching Speed:
   • Although it has a transition frequency of 250 MHz, it may not be fast enough for high-frequency switching applications compared to more modern MOSFETs or other BJTs with faster switching characteristics.

Pinout (TO-220 Package):

1. Pin 1 (Emitter – E):
   • The emitter is connected to the positive side of the circuit in a PNP transistor. In this case, current flows out of the emitter.
2. Pin 2 (Collector – C):
   • The collector is where the load is connected. In a PNP transistor, the collector current flows in through the collector.
3. Pin 3 (Base – B):
   • The base controls the switching of the transistor. A small current applied to the base allows a larger current to flow between the collector and emitter.

How to Use the BD136:

1. Switching Circuit:
   • In a switching application, a small current is applied to the base of the transistor to allow a larger current to flow between the collector and emitter, thus turning on the load.
2. Amplification Circuit:
   • In an amplifier circuit, the BD136 amplifies the small input signal at the base. The current through the collector-emitter path varies with the input, providing a stronger output signal.
3. Heat Management:
   • Since the BD136 has a relatively high power dissipation rating (30W), it is important to ensure adequate heat sinking when used in high-power applications to prevent overheating.
4. Base Resistor:
   • A current-limiting resistor is typically placed between the base and the control signal to ensure that the current into the base does not exceed safe limits for the transistor.