Sunday, September 04, 2011

BD139 and BD140 Complementary transistor

BD139 and BD140 Complementary transistor

This pair is my favorite when driving small solenoids or motors. SOT-32 12 Watts..

BD139 - NPN, 80V and 1.5A, 40 beta min.
BD140 - PNP, 80V and 1.5A, 40 beta min.

This means any small solenoid, relay or DC motor can be controlled with this. I would use it upto 24V DC and max of 1A for applications of full on and full off.

In applications like a regulator or variable motor control, you have to keep in mind the current thru and voltage across the transistor which results in power dissipation. Let us say it is driving 0.5A thru a motor in speed control and the Voltage across is 30V then the dissipation could be 30 x 0.5 = 15 Watts.

That is the reason we use switched regulators or switched controllers. So if we chop the DC and do PWM you have only the Switching losses and also a bit of DC loss. Switched controllers are also green, they save power for the same work done, but generate EMI-RFI and care is required in sensitive uV circuits. The transistors for switching are also special as they have to be fast with less capacitance, hence the mosfets are preferred in those applications. - ananth (san)

Blocks

80C51 Analog Analog-Design Analytical-Instrumentation Android Application-Notes-2 ASIC-Design ASIC-SOC-FPGA Bipolar-Transistors Capacitors Circuit-Archive Circuit-Design Circuit-Design-2 Communications Communications-Chips Component-Testing Computer-IC-Module Computer-Interfacing Control-Systems Design-Service Design-Service-2 Design-Service-3 Digital Discrete-Semiconductors DSP EDA EDA-2 EDA-3 EDA-4 EDA-5 Educational Educational-2 Electrical Electromechanical Embedded Embedded-2 Embedded-Applications Embedded-Systems-Tools Energy-Power Engineering-Services Engineering-Services-2 Engineering-Services-3 ESD-EMI-RFI Firmware Home-Automation Industrial-Automation IoT-WSN-M2M LED-Lighting Magazines Manufacturing-Services Materials-Nanotech Mechanical-3D-CAD Mechatronics Medical-Electronics MEMS Microcontroller Microelectronics Mixed Mixed-Semiconductor Mixed-Signal-Design Opamps Open-Hardware Optoelectronics Organizations-Associations Passive-Components PCB-Layout Photonics-Optics PIC Power-Devices Power-Electronics Power-Electronics-Design Process-Control Process-Control-2 Product-Safety Product-System-Design Projects Quality Reference Research-Institutes RF-Components RF-Design RF-Engineering-Services RF-Microwave RF-Semiconductor RF-Wireless-Networking Robotics Scientific-Software Semiconductors Sensors SMPS-Power-Supply Software-Code Spice-Simulation Standards Standards-2 Tech-Docs Tech-Media Technical-Computing Test-Measurement TM-Applications Training-Consulting Virtual-Instrumentation