Fast Delivery DigiKey customers in the United States can select from a range of delivery options, including Ground shipping at $6.99 and 2-Day at $12.99 Payment Types Payment in Advance by Wire Transfer Marketplace Product More Products From Fully Authorized Partners Average Time to Ship 1-3 Days. Please see product page, cart, and checkout for actual ship speed. Extra Ship Charges May Apply Articles & Blogs > A Deep Dive into Audio Jack Switches and Configurations A Deep Dive into Audio Jack Switches and Configurations By Ryan Smoot, Technical Support Engineer, Same Sky 2019-05-07 The audio jack is an industry-standard connector that has many potential uses in addition to providing basic audio connectivity. Understanding the wide variety of configurations available, including conductor count and switch options, enables designers to make the most of this familiar, compact, and reliable interconnect solution. The 2.5 mm or 3.5 mm audio jack is a familiar sight in smartphones, media players, hi-fi equipment, and many other devices. For imaginative designers it can be more than simply a convenient connection for an external speaker or a set of headphones, and can be used to connect a variety of accessories that may control other features of the device; a smartphone selfie stick featuring a camera-shutter release button is one example. Understanding how to take full advantage of this simple, yet versatile port begins with a closer look at the internal signal connections and switching mechanisms. Audio jacks are available as simple switchless connectors or may contain one or more switches that are actuated by inserting the plug. A switched connector is needed for purposes such as disconnecting internal speakers when headphones are inserted, to detect the insertion of an accessory, or if using an audio mixing board. If a switchless connector is used, accessory detection can be implemented with a dedicated audio-jack switch IC. Although adding to bill of materials and development costs, these ICs can provide additional features such as switch debounce and button-press detection. The datasheet for a given audio jack describes the combinations of conductors and switches available and how to specify them. The Same Sky SJ2-2531X-SMT audio jack is one example of a low-profile surface-mount connector that is available with either two or three conductors and can be ordered in switchless, one-switch, or two-switch configurations. Basic audio jack connections Figure 1 illustrates a basic switchless jack with three conductors. Imagine the plug being inserted from left to right so that the tip, ring, and sleeve are aligned with the corresponding contacts in the jack when the plug is fully inserted. Figure 1: Basic switchless three-conductor audio jack. (Image source: Same Sky.) Figure 2 shows how a switch is added to the terminal 2 position, to be activated by the plug tip. The datasheet refers to this as a tip switch. A similar switch can also be arranged at the ring terminal. Later, we will see how multi-ring jacks can support complex arrays of switches. Figure 2: Three-conductor audio jack with tip switch. (Image source: Same Sky Referring to Figure 2, when no plug is inserted, terminal 2 and terminal 10 are in contact so the switch is classified as normally closed. When the plug is fully inserted and the tip engages with terminal 2, the spring connector is pushed back and the circuit between terminals 10 and 2 is opened. More complex configurations Figure 3 shows how extra conductors and switches can be arranged. Clearly, the number and positions of ring conductors on the plug must match the contacts in the socket to actuate the switches according to the expected sequence. Figure 3: Four-conductor plug and socket with one tip and two ring switches. (Image source: Same Sky) So far, the switches described have been simple normally-closed types. However, other configurations are available such as normally open, Single Pole Double Throw (SPDT), and Double Pole Double Throw (DPDT) (Figure 4). These switches can be isolated from the audio signals, enabling them to be used to control various other circuits. Figure 4: Alternative switch configurations. (Image source: Same Sky) Some practical examples The connector configurations offered give designers many choices to fulfill a wide variety of signal-switching, insertion-detection, and system-control functions. Major examples include switching audio between speakers and headphones, as shown in Figure 5, as well as plug insertion and controlling other portions of the circuit that are independent of the audio signals. Figure 5: Switching audio between speakers and headphones. (Image source: Same Sky) In the first diagram of Figure 5, audio is played back through the built-in speaker when no headphone plug is inserted. The connector contains tip and ring switches that open when the plug is inserted, as shown in the second diagram. This disconnects the audio source from the speaker, while at the same time connecting the headphones into the circuit. Figure 6 shows how a normally closed tip switch is used to detect plug insertion and illuminate a warning indicator. Figure 6: Using a tip switch to detect plug insertion. (Image source: Same Sky) The connector shown in Figure 7 contains an SPDT switch that is used to switch the device between two operating modes by inserting or removing the plug. The connector contains ordinary tip and ring contacts, although terminals 4-6 are isolated from the audio signals on terminals 1-3. When no plug is inserted, terminals 4 and 5 are connected. Inserting the plug opens terminals 4 and 5, and instead connects terminals 5 and 6. This changeover can be used to switch the main system from one operating mode to another. Figure 7: Using the audio jack to switch between device operating modes. (Image source: Same Sky) Conclusion Offering small size and great versatility, the industry-standard audio jack is practical, reliable, and easy for designers and equipment users to understand. With only a little knowledge of the various features available, designers can take advantage of the jack to support extra features in new products that would otherwise require further discrete switches or accessory ports to be added. In this way, clever use of the audio jack can save bill of materials costs, simplify hardware design, and accelerate time to market for updated products that offer new features. Disclaimer: The opinions, beliefs, and viewpoints expressed by the various authors and/or forum participants on this website do not necessarily reflect the opinions, beliefs, and viewpoints of DigiKey or official policies of DigiKey. Related Videos Connector Solutions Same Sky connectors feature a wide range of specifications to help meet requirements for many design options. Audio Connectors Same Sky audio connectors support a wide variety of mounting styles and offer internal switches from 0 to 4 as well as SPDT, DPDT, and normally open options. 6.35 mm Audio Connectors Featuring cable-mount, panel-mount, and through-hole mounting styles with two or three conductors, horizontal or vertical orientations, and zero to three internal switches. Related Articles and Blogs Understanding Printed Circuit Board (PCB) Pin Connectors Although small, printed circuit board connectors serve an important role with dependable electrical connections between components and circuit board assemblies. Connector Tutorial There are many different kinds of connectors, all serve the same purpose but in different ways. This article discusses connectors and their typical applications. About this author Ryan Smoot, Technical Support Engineer, Same Sky With an extensive knowledge of Same Sky products, Ryan Smoot provides customers with a wide range of technical and application support capabilities in the field. His management of the Same Sky robust CAD model library further offers engineers with an invaluable resource for streamlining their product designs. Co-Browse By using the Co-Browse feature, you are agreeing to allow a support representative from DigiKey to view your browser remotely. When the Co-Browse window opens, give the session ID that is located in the toolbar to the representative. DigiKey respects your right to privacy. For more information please see our Privacy Notice and Cookie Notice . Thank you! Keep an eye on your inbox for news and updates from DigiKey! 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