Table of Contents
Introduction
The BD140 is a popular PNP power transistor used in medium power amplification and switching applications. It is designed to handle relatively high currents and voltages, making it suitable for audio amplifiers, motor drivers, and linear circuits. The transistor is commonly used in complementary push-pull configurations with its NPN counterpart BD139. With a maximum collector current of 1.5A and a power dissipation capacity of up to 12.5W, BD140 is ideal for applications that demand moderate power control with reliable performance.
BD140 Pinout
| Pin No. | Pin Name | Description |
|---|---|---|
| 1 | Base (B) | Controls the transistor biasing. Small current here controls larger current between collector and emitter. |
| 2 | Collector (C) | The main current-carrying terminal, connected to load. |
| 3 | Emitter (E) | Connected to ground or the negative supply. Current flows out from this terminal in PNP type. |
Pin Configuration (Left to Right, facing flat side):
1 → Base, 2 → Collector, 3 → Emitter
Key Specifications
| Parameter | Value |
|---|---|
| Transistor Type | PNP |
| Collector–Emitter Voltage (Vce) | -80V |
| Collector–Base Voltage (Vcb) | -80V |
| Emitter–Base Voltage (Veb) | -5V |
| Collector Current (Ic) | -1.5A |
| DC Current Gain (hFE) | 40 – 250 |
| Power Dissipation (Ptot) | 12.5W |
| Transition Frequency (fT) | 190 MHz |
| Package Type | TO-126 |
Features
- Medium power PNP transistor
- High DC current gain
- Low saturation voltage
- Good frequency response
- Suitable for linear and switching circuits
- Complementary to BD139 (NPN)
Equivalent / Alternative Transistors
- BD136
- BD138
- BD182
- 2SB649
- MJE350
Applications
- Audio amplifier output stages
- Motor control circuits
- Power regulators
- Signal amplification
- Switching of medium loads
