Different Packages of Transistors
At Regent Electronics, we’re committed to providing comprehensive insights into electronic components. Today, let’s explore the different packages of transistors, a continuation of our transistor series. This guide covers key package types like TO-92, TO-18, TO-220, TO-3, and Small Outline Transistor (SOT) formats, among others. Each package offers unique properties, applications, and benefits for various electronic projects.
Overview of Transistor Packages
Transistor packages are the protective housings that encase transistor components. They serve several critical purposes:
- Establish connections between the internal transistor and external circuits.
- Protect sensitive internal parts from environmental damage.
- Dissipate heat efficiently using heatsinks in high-power applications.
The most common package standards include the “TO” (Transistor Outline) and “SOT” (Small Outline Transistor) series, with variations designed to meet specific application requirements.
Low-Power vs. High-Power Transistor Packages
- Low-power transistors are often housed in plastic packages with a flat surface.
- High-power transistors may feature metal or hybrid plastic-metal construction. Metal tags in high-power packages often act as heat sinks, enabling efficient thermal dissipation during operation.
The “TO” Series Packages
TO-92 Package
The TO-92 is a compact, plastic-molded package commonly used for low-power applications. It features a flat front for labeling and a semi-circular back. Its small size makes it ideal for space-constrained designs, though it has limited heat dissipation capabilities.
Specifications:
- Body Dimensions: 4.58 mm x 4.58 mm
- Body Thickness: 3.86 mm
- Lead Length: 14.47 mm
Common Transistors in TO-92:
- BC547 (NPN general-purpose)
- BC558 (PNP general-purpose)
- 2N7000 (N-channel FET)
- PN2222A (plastic version of 2N2222)
TO-18 Package
The TO-18 package is a metal can design known for its hermetic seal, protecting components from moisture and contaminants. It’s slightly larger than the TO-46 and provides excellent reliability in demanding environments.
Specifications:
- Base Diameter: 5.5 mm
- Cap Height: 4.8 mm
- Lead Length: 12.7 mm
Common Transistors in TO-18:
- 2N2222A (NPN general-purpose)
- 2N2646 (UJT)
- 2N5114 (P-channel FET)
TO-220 Package
The TO-220 package is a popular choice for medium to high-power applications. Its metal tab serves as a built-in heat sink and can be mounted onto larger heat sinks for additional cooling. TO-220 is widely used in power transistors, MOSFETs, and voltage regulators.
Specifications:
- Body Dimensions (excl. tab): 9.2 mm x 9.9 mm
- Body Thickness: 4.5 mm
- Lead Length: 13.1 mm
Common Transistors in TO-220:
- TIP31C (NPN power transistor)
- IRFZ44N (N-channel power MOSFET)
- IRF5305 (P-channel power MOSFET)
TO-3 Package
The TO-3 is a robust, all-metal package designed for high-power applications. Its durable construction allows for excellent thermal dissipation, making it ideal for power transistors and SCRs.
Specifications:
- Base Dimensions: 39.3 mm x 26.6 mm
- Cap Diameter: 22.2 mm
- Lead Pitch: 10.9 mm
Common Transistors in TO-3:
- 2N3055 (NPN power transistor)
- 2N5686 (NPN high-power transistor)
- 2N2955 (PNP power transistor)
Small Outline Transistor (SOT) Packages
SOT-23 Package
The SOT-23 is a surface-mount package known for its compact size and suitability for small-signal transistors. It measures just 2.9 mm x 2.4 mm x 1.1 mm, making it ideal for densely packed circuit boards.
Common Transistors in SOT-23:
- BC857 (PNP general-purpose)
- BC847 (NPN general-purpose)
- SI2302 (N-channel MOSFET)
SOT89-3 Package
The SOT89-3 is a three-lead surface-mount package designed for moderate power applications. Its wide lead tab aids in heat dissipation.
Specifications:
- Body Dimensions: 4.5 mm x 2.5 mm x 1.5 mm
- Lead Pitch: 1.5 mm
Common Transistors in SOT89-3:
- BFQ540 (NPN general-purpose)
- ZX5T3Z (PNP power transistor)
Conclusion
Understanding the various transistor packages is crucial for selecting the right component for your application. Whether you’re designing low-power circuits or high-power systems, Regent Electronics offers a wide range of transistors in TO and SOT packages to meet your needs. Explore our catalog today for reliable and high-performance electronic components!