COMPONENT PACKAGES

SOT-223 Component Package

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Overview

NameSOT-223 (Small-outline Transistor 223)
Synonyms
  • DCQ (SOT-223-5, Texas Instruments)
  • DCY (SOT-223, Texas Instruments)
  • MP04A (National Semiconductor)
  • PG-SOT-223-4 (Infineon Technologies)
  • R-PDSO-G6 (SOT-223-5, Texas Instruments)
  • ST Package (Analog Devices)
  • TO-261-4
Variants
  • SOT-223-3 (3 pin excl. tab)
  • SOT-223-4 (4 pin excl. tab)
  • SOT-223-5 (5 pin excl. tab)
Similar To
MountingSMD
Pin Count3, 4, 5 (excl. tab)
Pitchn/a
SolderabilityEasily solderable by hand
Thermal ResistanceSOT-223-3
  • \(T_{JA} = 174^{\circ}{\rm C}/W\) (standard footprint)
  • \(T_{JA} = 75^{\circ}{\rm C}/W\) (\(300mm^2\) heatsink area)
  • \(T_{JA} = 63^{\circ}{\rm C}/W\)(\(600mm^2\) heatsink area)
  • \(T_{JA} = 27^{\circ}{\rm C}/W\)(one square inch copper fill surrounding package)
SOT-223-5
  • \(55-165^{\circ}{\rm C}/W\) (see the SOT-223-5 section below)
Dimensionsn/a
3D Modelsn/a
Common Uses
  • MOSFETs
  • Load switches
  • High-power linear regulators
  • Current sources

Conflicting Naming Conventions

This page associates the x in SOT-223-x to stand for the number of pins excluding the tab. This is the most popular convention.

SOT-223-3

The SOT-223-3 (TO-261AA) component package is the most common variant within the SOT-223 family. It looks similar to the SOT-23 package, but with a tab on one side instead of legs.

A 3D render of the TO-261AA (SOT-223-3) component package.

A 3D render of the TO-261AA (SOT-223-3) component package.

It is commonly used for medium-power linear regulators and load switches.

Thermal Resistance

Texas Instruments gives the following thermal resistance data for the SOT-223-3 package (taken from http://www.ti.com/lit/ds/symlink/tps7b6933-q1.pdf, as of Dec 2017, URL is unavailable).

PropertySymbolValue
Junction-to-ambient thermal resistance\(R_{\theta JA}\)\(64.2^{\circ}C/W\)
Junction-to-case (top) thermal resistance\(R_{\theta JC(top)}\)\(46.8^{\circ}C/W\)
Junction-to-board thermal resistance\(R_{\theta JB}\)\(13.3^{\circ}C/W\)
Junction-to-top characterisation parameter\(R_{\psi JT}\)\(6.3^{\circ}C/W\)
Junction-to-board characterisation parameter\(R_{\psi JB}\)\(13.2^{\circ}C/W\)

All of the parameters in the above table were measured with the SOT-223-3 package soldered to a JEDEC standard high-K profile, JESD 51-7, 2s2p four layer board with 2-oz copper. The copper pad was soldered to the thermal land pattern.

The thermal resistance of the TO-261AA (SOT-223-3) component package for various PCB footprints.

The thermal resistance of the TO-261AA (SOT-223-3) component package for various PCB footprints.

Standard Linear Regulator Pinout

The SOT-223-3 package is commonly used for small, medium-power linear regulators. There is a de-facto standard pinout that many manufacturers use when incorporating a linear regulator into the SOT-223-3 package:

The de-facto standard pinout for a linear regulator inside a SOT-223-3 package. This image also shows the standard PCB footprint used to achieve a low thermal resistance. Image from http://www.ti.com/.

The de-facto standard pinout for a linear regulator inside a SOT-223-3 package. This image also shows the standard PCB footprint used to achieve a low thermal resistance. Image from http://www.ti.com/.

Standard Load Switch Pinout

The SOT-223-3 package is commonly used for smaller low and high-side load switches. As such, there is a de-facto standard pinout that many manufacturers use for load switches in the SOT-223-3 package:

The de-facto standard pinout for a load switch in a SOT-223-3 package. Image from http://www.infineon.com/.

The de-facto standard pinout for a load switch in a SOT-223-3 package. Image from http://www.infineon.com/.

SOT-223-4

This variant can be confused with the three pin and one pad variant (SOT-223-3) if you decide to count the pad as well as the pins in the number.

A 3D render of the SOT-223-4 component package. Image from http://www.datasheetdir.com/.

A 3D render of the SOT-223-4 component package. Image from http://www.datasheetdir.com/.

SOT-223-5

Dimensions

Below are the dimensions of the SOT-223-5 package as specified by Texas Instruments.

The dimensions of the SOT-223-5 component package. Image from http://www.ti.com/.

The dimensions of the SOT-223-5 component package. Image from http://www.ti.com/.

Footprint (Land Pattern)

Below is the recommended footprint (land pattern) for the SOT-223-5 component package as specified by Texas Instruments.

A recommended footprint (land pattern) for the SOT-223-5 component package. Image from http://www.ti.com/.

A recommended footprint (land pattern) for the SOT-223-5 component package. Image from http://www.ti.com/.

Thermal Resistance

Below is a graph showing the thermal resistance of the SOT-223-5 package with varying copper area.

Graph of thermal resistance vs. copper area for the SOT-223-5 component package. Image from http://www.ti.com/.

Graph of thermal resistance vs. copper area for the SOT-223-5 component package. Image from http://www.ti.com/.

As you can see, as the copper area increases, the thermal resistance decreases asymptotically to around \(55^{\circ}{\rm C}/W\).

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