From Structure to Applications: A Comprehensive Overview of the Key Differences Between TO-220AC and TO-220F Packages

Although the TO-220AC and TO-220F both belong to the TO-220 package family and share a similar外形, they differ significantly in key aspects such as structural design, electrical and thermal characteristics, and mounting requirements. These differences also determine that each is suited to distinct application scenarios.

Let’s start with an introduction. TO-220AC

The TO‑220AC is a dual‑lead through-hole variant within the TO‑220 package family, commonly used to house power devices such as SiC Schottky diodes. It is specifically designed to meet the single‑phase conduction requirements of circuits. Below is a detailed description of its key features, distinctions from similar packages, and typical application scenarios.

Core Structure and Characteristics

Pins and Internal Structure: It conforms to the TO‑220‑2 package specification, featuring only two pins and integrating a single chip internally, with both positive and negative polarity, making it a single‑transistor device. By contrast, the TO‑220AB, also part of the TO‑220 series, employs a three‑pin configuration and houses two chips connected in common‑cathode fashion—this is the most fundamental distinction between the two.

Appearance and Common Attributes

It has the same package dimensions as the TO‑220AB, both being through-hole packages suitable for through-hole mounting. The bottom features a metal heat sink that can be secured to an external heatsink with screws, enhancing thermal conductivity; however, the metal pad is electrically connected to the leads, so an insulating washer must be added during installation to prevent short circuits.

Parameter compatibility

Within the same model series, devices packaged in TO‑220AC and TO‑220AB typically share identical electrical specifications. For example, ASEMI’s MBR10200 and MBR10200AC both have ratings of 10 A and 200 V; the only difference is the package type, which determines their suitability for different circuit applications.

TO-220AC is a package type and does not, by itself, determine the device’s maximum voltage rating. The voltage rating is dictated by the chip type and model housed within the package. Voltage ratings can vary significantly from one device to another; currently, this package type covers a range from 15 V to 1200 V.

The maximum current rating of the TO‑220C package is not determined by the package itself, but rather by the type and specific model of the device housed within. This package is commonly used to encapsulate devices such as bidirectional SCRs, Darlington transistors, and power bipolar transistors, with current ratings ranging from 4 A to 70 A.

Next, we will introduce TO - 220F

The TO‑220F is a fully plastic, fully isolated through-hole package within the TO‑220 family (the “F” stands for “Fully Isolated”). It is commonly used to house power devices such as power MOSFETs, SiC diodes, and fast-recovery diodes. Thanks to its high insulation performance, it is well suited for medium-power applications with stringent circuit‑safety requirements. Below are its key features, typical applications, and a comparison with similar packages:

Core Structure and Characteristics

All‑plastic insulation design: It closely resembles the TO‑220AC package, featuring a 3‑lead through‑hole configuration and a plastic enclosure with a heat sink. However, in the TO‑220F, the metal heat sink is entirely encapsulated by plastic and electrically isolated from both the internal die and the leads, achieving an insulation withstand voltage of up to 2500 VAC for 1 minute. During installation, no additional insulating washers are required; the device can be mounted directly onto a heatsink while effectively preventing leakage current or short circuits from the heat sink, thereby simplifying the assembly process.

Balancing heat dissipation and compatibility

The heat sink is tightly bonded to the internal components, enabling efficient thermal conduction and meeting the cooling requirements of medium‑power devices; when paired with a heatsink, it further reduces operating temperatures. Additionally, its leads conform to industry‑standard specifications, ensuring excellent compatibility, while soldering onto a PCB or using a plug‑in configuration is both convenient and straightforward. Its dimensions also match those of mainstream TO‑220‑style packages, facilitating optimized circuit‑board layout.

Typical application scenarios: Due to its outstanding insulation and reliability, this package is widely used in power control, rectification, and conversion circuits across multiple industries.

TO‑220F is merely a package type for power devices, similar to the earlier TO‑220AC package. It does not itself determine the maximum current; rather, the specific maximum current is dictated by the chip model and device type housed within the package—such as MOSFET, IGBT, or rectifier diode. Current ratings vary significantly across different models, spanning a broad range from 4.5 A to 300 A.

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