Last Updated on October 22, 2023 by Kevin Chen
SOT stands for Small Outline Transistor, and both transistors are surface mount transistors used in many electronic applications.
There are different other transistor packages. One of them is SOT23 and the other one is SOT323. Both transistors are similar in size, but there are some differences between them that make all the difference.
So, should I choose SOT23 or go for SOT323?
We are here to help you make the right choice.
In this guide, we are going to discuss the differences between the two transistor packages.
At the end, we will even give you hints for choosing the best transistor packaging suppliers in China.
How does a SOT work
First things first, before we get into the differences between SOT23 and SOT323, let’s have the basic knowledge of how SOT works.
A small outline transistor (SOT) works by controlling the current in a circuit, and two transistors are used to control its operation. The first transistor is called the base, which is connected to an input voltage.
The second transistor is called the collector, which is connected to a load such as resistor or LED (Light Emitting Diode). The transistors act like switches by either conducting or blocking the current flow.
The fact that it is a small outline means that it provides a small footprint on whichever application that it will be used.
And how is this relevant to the end user? Small transistors are beneficial as they reduce the space needed for your design, which can help you save costs in production.
Why are the numbers important?
In this article, our focus is the SOT23 and SOT323. What is the relevance of the numbers?
The numbers are indicative of transistors with different dimensions. Generally speaking, SOT23 transistors have a maximum size of 2mm in width and 3 mm in length, while the maximum size for the SOT323 transistors is 3 mm in width and 3 mm in length.
It can be noted here that, although both transistor packages may have similar sizes, the transistors they use are not. SOT23 transistors have three channels and SOT323 transistors have five channels.
What does plastic and surface-mounted mean?
The transistors that come under the SOT package are made of plastic and they are surface-mounted transistors. This means that they are attached to a board or any other element, without having to be connected through soldering.
This makes the installation process much simpler and faster than it would be with soldered transistors. It also reduces the space needed for transistors.
Overview of SOT23
SOT is a surface-mounted package with small outlines and transistors. It is widely used in many electronic applications.
SOT23 transistors come with three leads, where the leads are mounted on one side of the transistor. The SOT23 package is very small and has a height of 2 mm or 0.08 inches.
The three pins are arranged in an inverted U shape, and the transistors are usually marked with a number that corresponds to the semiconductor material used in them.
Overview of SOT323
On the other hand, SOT323 transistors come with four leads instead of three and they are mounted on two sides of the package. The pins are arranged in a square shape and the transistors are usually marked with a number that corresponds to the semiconductor material used in them.
The SOT323 transistors have a slightly larger size than the SOT23 transistors, making it easier to connect and solder them to other components.
Key features of SOT23
Here are the most important features of SOT23 that you should know:
-Has three terminals: These terminals are used to control and regulate the current flow in a circuit.
-Smaller size: Due to its small size, SOT transistors can save space and costs in applications requiring a smaller footprint.
-Easy to connect: SOT transistors can be connected easily and quickly with other components, making them ideal for high volume production.
-Easily compatible with other packages: SOT transistors are compatible with other packages such as DIPs and TO-220.
-Affordable: SOT transistors are generally cheaper than other packages.
Key features of SOT323
Here are the most important features of SOT323 transistors:
-Has four pins: This allows for more control over the current flow in a circuit by providing more control points.
-Larger size: SOT transistors have a slightly larger size than the SOT23 transistors, making it easier to connect and solder them.
-High performance: The transistors used in the SOT323 package are typically of higher performance compared to transistors used in other packages.
-Greater power dissipation: Due to its larger size, the SOT323 transistors can dissipate more power than transistors used in small packages.
SOT23 vs SOT323: What’s The Difference Between Them?
Now let’s analyze various areas of differences that separate SOT23 and SOT 323 transistor packages.
Package height
Both packages have low heights. The height for the SOT323 is 1.1mm while that for the SOT323 is 1.2mm.
What does this mean?
This means that the SOT23 transistors have a slightly lower profile than the SOT323 transistors, making them more suitable for applications which require transistors to fit into limited space.
Number of leads
The number of pins is different in both packages. The SOT23 transistors are equipped with three pins while the SOT323 transistors have four pins.
What does this mean?
This means that SOT23 transistors can be used for simple tasks while the SOT323 transistors are better suited for more complex operations as they provide more control and flexibility due to their additional pin.
Overall size
The overall size of both transistors is different with the SOT23 transistors having a smaller size than the SOT323 transistors.
How is this relevant?
This means that the SOT23 transistors are more suitable for applications which require transistors to fit into limited space, while the larger size of the SOT323 transistors makes them ideal for applications requiring higher power dissipation.
Working voltage range
Working voltage of an SOT refers to the maximum voltage at which transistors can be safely operated.
The working voltage range for SOT23 transistors is 5V – 20V while the working voltage range for SOT323 transistors is 6V – 30V.
What does this mean?
This means that SOT323 transistors can handle higher voltages, making them more suitable for applications requiring transistors to withstand higher voltages.
Load capacitance
Load capacitance is the amount of charge that transistors can handle. The load capacitance for SOT23 transistors is 6 pF while the load capacitance for SOT323 transistors is 3.2 pF.
What does this mean?
This means that SOT323 transistors can handle more current than SOT23 transistors, making them suitable for higher power applications.
Leakage current
We can define the leakage current of a transistor as the current that flows through the transistors when it is not in active mode. The leakage current for SOT23 transistors is typically higher than that of SOT323 transistors. This is mainly because transistors of SOT323 packages have better insulation and tighter construction than transistors of SOT23 packages.
What does this mean?
This means that transistors in the SOT323 package are more suitable for applications requiring transistors to operate at lower leakage currents.
Price
The cost of both transistors varies depending on their manufacturer and the transistors used in their construction. Generally, SOT323 transistors tend to be more expensive than SOT23 transistors as transistors of this package require greater power dissipation and are made from higher-quality materials.
But again, the price will depend on the supplier that you choose. Some are quite affordable while others are expensive.
So, it will be good to contact the transistor packaging supplier directly to find out their prices.
Heat dissipation
This refers to the rate at which transistors dissipate heat. This is a key feature to look out for when buying transistor packaging.
If not carefully considered, it can lead to the overheating issues in a device.
The SOT323 transistors are usually better in this regard as they can handle higher power dissipation than the transistors used in SOT23 packages.
What does this mean?
This means that transistors used in the SOT323 package are more suitable for applications requiring transistors to operate in higher temperatures or dissipate more heat.
Compatibility with other packaging outlines
Compatibility in this context refers to transistors’ ability to fit into other transistors’ outlines.
SOT23 transistors are compatible with numerous transistors packaging including TO-92, SC-70 and SOD-323 while the compatibility of transistors in the SOT323 package is limited to only a few packages such as SC-89 and TO-263.
What does this mean?
This means that transistors of the SOT23 package are more suitable for applications that require transistors to be compatible with other transistors’ outlines.
Which one should I choose?
So, now you know the differences between SOT23 and SOT323 transistors. Now the question is: which one should you choose?
The answer to this depends on two factors: your goals and available resources.
If you are looking for transistors that can handle higher voltages and dissipate more heat, transistors of the SOT323 package are a better choice.
However, if you have limited resources and require transistors to be compatible with other transistors’ outlines, transistors of the SOT23 package would be more suitable for your needs.
Ultimately, it is up to you to decide which transistors package will best meet the needs of your application.
And once you have made up your mind, let ICRFQ be your trading partner. We are a trusted supplier of transistors in China.
If you want to find more Electronic Components Distributors, please check out the following articles:
Electronic Components Distributors In the USA
Electronic Components Distributors In UK
Electronic Components Distributors In China
Electronic Components Distributors In India
Electronic Components Distributors In Singapore
Electronic Components Distributors In Malaysia
Electronic Components Distributors In Vietnam
Electronic Components Distributors In South Korea
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