The process of manufacturing consumer electronics is fraught with challenges. One of the best ways to tackle these issues at the onset is to prevent them from happening. Using the right packages for the devices or applications also helps.
For that purpose, the SOT23 was released to aid the packaging of consumer electronics, especially those using transistors. In this article, you are going to learn more about how the SOT23 package works.
The Family of SOTs
SOT23 package is one of the transistor packages belonging to the broader Small Outline Transistor (SOT) family. It is also one of the most used of all the other SOT packages and that is because of the excellent packaging options it provides to the targeted consumer electronics.
How does an SOT work?
A Small Outline Transistor (SOT) works by providing a wide range of small footprint or compact Surface Mountable transistors, which are used to protect specific consumer electronics.
The SOT23 Priority
The SOT23 variant of the Small Outline Transistors (SOTs) is prioritized because of the improved performance and the extended use cases to both voltage regulators and diodes.
The Essence of the Numbers
Worthy of mentioning is that the SOT23 package is just one of the several SOTs. Of what use is it to number the transistors?
The numbering is serial, meaning that the SOT23 is only the 23rd Small Outline Transistor (SOT) in the line of other SOTs.
It doesn’t end there. The SOT23 also has additional numbers attached to it and separated by the hyphen. For example, you may see a numbering like SOT23-5. It simply means that the attached number is for the pin count, thereby, implying that the SOT23-3 has a total of five (5) pins in the package.
Understanding the SOT23 Datasheet
Reading or interpreting the data in the datasheet may seem confusing, especially when you consider that there have been some mix-ups in the SOT23’s numbering. For example, it is wrong to say that the SOT26 is a 26-pin count Small Outline Transistor (SOT). The ideal numbering method is to enter the variant of the SOT first, which in this case, is the SOT23. Then, a hyphen would be added to separate the variant from the number of pins it has.
Therefore, the correct number structure for the above should be SOT23-26, assuming the SOT has up to 26 pins.
When it comes to the SOT23 datasheet, it is mostly up to the manufacturer of the transistors to determine how to structure it. Below are some of the likely structuring scenarios for the datasheet:
Using SOT23 Can Serve for all Pins
The SOT23 manufacturer may decide to stick to the original SOT23 designation. While it is feasible to use this if the transistors don’t cover additional parameters like multiple diodes, it is up to the manufacturer to make the final decision.
The manufacturer can either stick to the original SOT23 designation for the basic transistors without double or triple diodes. The manufacturer can also decide to use the hyphen to specify the number of diodes or pins the transistors cover. In that case, we will have something like:
- SOT23-6 for a 6-pin count Small Outline Transistor (SOT)
- SOT23-3 for a 3-pin count Small Outline Transistor (SOT).
SOT23 Variants
First, understand that the SOT23 is just a number and doesn’t have a definite meaning. It became popular following conventions and through the consistency of mentioning it in Small Outline Transistor (SOT) datasheets.
Before now, the JEDEC standard was used as the standard for naming these SOT23 variants were TO-236AB.
With that being said, here are some of the variants of the SOT23 package:
- SOT23-3
- TOB-236AB
- SMT3
- SC59A
- SOT346
- TO236AA
The Difference between SOT23 and SOT23-3
Although the popular opinion is that there is no difference between the SOT23 and the SOT23-3, there appears to be a tiny line of disparity between the two.
The major difference in the body sizes. For example, when comparing the devices made with the SOT23-3 and those made with the SOT23, a noticeable difference is seen in the mass. Despite being on the same footprint, the SOT23-2 package has a slightly larger body size than the SOT23 package does.
Another clear difference between the two is in the applications or use cases. For instance, the SOT23-3 has seen found its way into several simpler Integrated Circuits (ICs) like LDOs unlike the SOT23, which is commonly used for consumer electronics using both voltage regulators and diodes.
Features of the SOT23 Package
You need to understand that the SOT23 package has some features that do not only make it outstanding from the other Small Outline Transistor (SOT) packages, but also bolster the performance when used on the target devices.
These are some of the package’s features:
1. Application-Based Pin Counts
The number of pins used in the SOT23 package vary by the applications or use cases. The thermal performance or requirement of the target applications may also influence the number of pins used in the package.
To that end, a higher thermal application needs an SOT23 with several pins to balance the needed performance.
2. SOT23 Packages are Affordable
If you are looking for a cost-effective way of providing additional protection for consumer electronics, adding any of the SOT23 packages to the circuit board can make all the difference.
The integration of a Copper (Cu) wire interconnect is the major reason why the SOT23 packages are affordable.
3. SOT23 Packages are Ideal for Small Footprint Applications
Some applications require a smaller footprint, which is why SOT23 packages readily come in handy to provide flexible switching and amplifying of electrical signals and power on consumer electronics.
4. Compatibility with the other Packages
SOT23 is also compatible with other types of semiconductor and consumer electronics packages. Of particular mention is the handling of the smaller footprint Integrated Circuits (ICs) previously used in either the TSSOP or the SOIC packages.
Conclusion
SOT23 makes the job of regulating voltages and bolstering the performances of consumer electronics easier. Note that there is a smaller variant of the SOT23, called the Thin Small Outline Transistor (TSOP).
Generally, Small Outline Transistor 23 (SOT23) is your go-to for small footprint and higher surface mounted transistors optimized for consumer electronics.
