The TO-220 is a common package type used for a variety of electronic components, including power transistors, voltage regulators, and fast recovery diodes. The TO in TO-220 stands for Transistor Outline, an industry standard for the session size and form originated by JEDEC (Joint Electron Device Engineering Council).
The TO-220 package is designed for through-hole mounting and is crafted with a metal tab and a hole for easy attachment to a heatsink. This design allows heat generated from the electronic component to be efficiently dissipated, making the TO-220 optimal for high-power applications.
The typical TO-220 package consists of a metal tab and three pins, though there are versions available with more pins for different needs. The metal tab is usually connected to the center pin. This setup leads to efficient electronics design because the thermal and electrical characteristics of the device are taken into consideration.
Various TO220 variants exist like TO-220AB, TO-220AC, TO-220F, etc., each designed to offer specific advantages for different applications. For example, the TO 220F variant has an insulated tab, making it a viable choice for applications requiring electrical isolation.
TO-220 packages are widely used in power and electronics industry thanks to their robustness, effective heat dissipation, and ease-of-use. These characteristics make them suitable for use in a wide range of devices and appliances, from audio equipment to automobile systems, and power supply equipment.
TO 220 Package Dimensions and Pinout
Dimension
TO220 Package Dimension Diagram
The TO-220 is a standard package for semiconductors and has specific physical dimensions. However, please note that dimensions might have slight variations based on manufacturers or specific versions of the TO220 package. The typical dimensions can be described as follows:
- Total length: Around 15 mm
- Total width: About 10 mm
- Thickness (excluding leads and heatsink tab): Roughly 4.5 mm
- Lead length: Around 14 mm
- Lead separation or pitch (centre to centre of lead at the point they emerge from the case): 2.54 mm (0.1 inches), matching the standard breadboard and perfboard pitch
- Diameter of hole in the heat tab: Roughly 3.2 mm
Pinout
TO220 Package Pinout Diagram
The TO-220's heatsink tab is usually connected to the center pin (or to some part of the semiconductor die). When incorporating a TO-220 package component in a circuit, it's crucial to account for these dimensions. This ensures adequate space is provided for both the component and any heatsink that it's attached to. It also ensures that the device fits on the printed circuit board (PCB) and doesn't interfere with neighbouring components.
Type of TO-220 Package
Different Types of TO220 Package
The TO-220 package is highly versatile and comes in many variants to cater to a range of electronic components and applications. Here are a few commonly used types:
Standard TO-220: This is the most common variant, with a basic structure that includes a tab for attaching a heatsink, and three leads.
TO-220F (Full Pack): This variant has a fully insulated tab, so no electrical contact is made when the device is mounted to a heatsink. This can be beneficial in applications where electrical isolation is important.
TO-220AB: This variant typically has the same three leads like a standard TO-220 but an extended metal tab area for better heat dissipation.
TO-220AC: This is another variant of TO-220 with a different lead bend than the regular TO-220.
TO-220D: This variant has a horizontal orientation with side-leads.
In addition to these, multiple pin configurations can be found for the TO-220 package, beyond the standard three leads. This includes variations with two, four, five, six, or even seven leads.
Recommended Reading: TO-220AB vs TO-220-3
Advantages of TO220 Package
The TO-220 package offers several key advantages, which have contributed to its widespread use in the electronics industry:
1. Efficient Heat Dissipation: One of the most significant advantages of the TO-220 package is its robust heat dissipation capabilities. The metal tab on the package can be bolted directly to a heatsink, efficiently transferring heat from the component and helping to prevent overheating. This makes the TO-220 package well-suited for components that are expected to handle substantial power loads and generate significant heat.
2. Versatility: The TO-220 package can be used with a wide variety of electronic components, including but not limited to transistors, voltage regulators, and fast recovery diodes. Moreover, while the standard TO-220 package includes three leads, variants with more or fewer leads are also available, increasing the range of applications where the package can be used.
3. Durability: The TO-220 package is robust and designed to withstand demanding conditions, aiding in the overall longevity of the component it houses.
4. Ease of Assembly: The TO-220 package is a through-hole component, meaning that it can be manually inserted and soldered to a PCB. This makes it relatively easy to handle during assembly and ideal for prototyping and small production runs.
5. Wide Range of Variants: Thanks to the popular TO-220F insulated packages, components can be directly attached to heatsinks without the need for electrical isolation. Other variants cater to different spacing or size needs, increasing design flexibility.
6. Cost-Effective: Last but not least, TO-220 packages are cost-effective which makes it a suitable choice for a variety of applications where cost is also a factor.
Disadvantage of TO 220 Package
While the TO-220 package has many advantages and is quite popular within electronics design, it does have a few drawbacks that engineers must keep in mind:
Size and Space: The TO-220, being a through-hole component, requires more space on a printed circuit board (PCB) than equivalent surface mount components. For compact electronics, especially consumer electronics where size limitations are crucial, the TO-220 package might not be the most practical solution.
Not Suitable for High-Speed Circuits: The lead inductance and the relatively long length of the leads can be a disadvantage in high-frequency applications. The longer leads may cause unwanted parasitic inductance and resistance, which can affect the performance of the circuit at high speeds.
Heat Management: Despite the TO-220 package's effective heat dissipation capability through the metal tab, additional heat management is often required for high power applications, such as the use of thermal paste or a heatsink. These add-ons can increase manufacturing complexity and costs.
Mounting Necessity: In order to benefit from its thermal dissipation feature, the TO-220 package must be correctly mounted to a heatsink. Not mounting it correctly or failing to use thermal paste can lead to overheating and potential failure of the component.
No Isolation in Standard Package: In the standard TO-220 package, the heat sink tab is typically electrically active (usually connected to the middle lead). If a circuit designer does not want the heatsink to be electrically active, they must choose an isolated version of the TO-220, such as the TO-220F, or take the necessary steps to ensure isolation when mounting the package.
These disadvantages don't negate its value, but they are considerations to keep in mind when choosing the type of package for electronic components in any particular application.
What is the difference between TO-220 and to 220F?
TO-220(Left) and TO-220F(Right) Package
The primary difference between the TO-220 and TO-220F packages is related to the design and functionality of the metal tab that's typically used for heat dissipation.
TO-220
In the standard TO-220 package, the metal tab is typically connected electrically to the middle lead (often the collector of a transistor or the drain of a FET), or some part of the semiconductor die. This means that when the component is mounted to a heatsink, an insulating layer is often necessary to prevent electrical short circuits, depending on the design of the system.
TO-220F (Full Pack) Package
The "F" in TO-220F stands for "Fullpack", indicating that the package has a fully insulated tab. This means the tab is electrically neutral and not connected to any of the internal semiconductor structures. This design allows the TO-220F to be mounted directly to a heatsink without the need for additional insulation to prevent electrical shorts. This can simplify assembly, but it might come with a minor loss in thermal conductivity due to the insulating layer.
Both package types have the same basic form and pin configuration, so the choice between the two typically depends on the specific requirements of the system being designed. In a situation where electrical isolation is crucial, a TO-220F might be preferred, whereas a standard TO-220 might be perfectly suitable in other instances. Always consult the relevant datasheets for exact specifications and guidelines.
FAQ
1.Why upgrade TO-220?
Upgrading to a T0-220 package is often done in pursuit of improved thermal handling and greater power capabilities.
2. What is the difference between TO-220 and TO-220AB?
The TO-220-3 (also known as TO-220AB) is the most common variant within the TO-220 package range. TO-220AB is a specific JEDEC designation. The 'AB' signifies that the component conforms to specific measurement specifications and has a straight lead three-pin configuration. TO-220-3 is a generic name used for devices with a TO-220 body and three pins. This has become increasingly common as the same package offers options with 2, 3, 5, or even 7 pins to choose from.
3. Does the TO-220 package require a heatsink?
As a high-power package, a TO-220 often requires a heatsink for applications with high thermal demand. The metal tab is designed to facilitate heat dissipation and can connect to a heatsink. However, the need for a heatsink depends on the power being dissipated, the ambient conditions, and the maximum allowable junction temperature of the device.
4. Can the metallic tab on a TO-220 package create an electrical short circuit?
Yes, in many TO-220 devices the metal tab is internally connected to one of the leads (often the middle one). If this tab makes an unintended contact with other conductive material, it could potentially create an electrical short circuit. So, it's important to insulate it in designs where it may come into contact with other conductive elements.
5. What is the TO-220F package?
TO-220F, where "F" stands for "Full Pack", is another variant of the TO-220. In this version, the metal tab is electrically insulated from the internals of the device, thus reducing the risk of short circuits when mounting to a heatsink.
6. Why is the TO-220 package widely used?
The TO-220 package is commonly used because it offers good heat dissipation qualities due to its metallic tab. This feature makes it quite suitable for high-power components such as power transistors and voltage regulators.