Reference design for a headphone switch application which can automatically detect if a headphone has a mic or not.
Have you ever wondered how phones or computers can detect if a wired headset has a microphone or not? To learn how devices can detect headphones and how you can include this feature in your device Texas Instruments (TI) has released a reference design which can detect headphones with mic and without mics.
The TIDA-00006 is a headset detection switch to detect 3-pole or 4-pole 3.5mm accessories. A 3-pole headphone jack, also known as a TRS (Tip Ring Sleeve) jack, has three separate conductive elements or metal bands on the plug. The tip carries the left audio signal, the middle ring carries the right audio signal, and the sleeve is the ground connection. A 4-pole headphone jack, also known as a TRRS (Tip Ring Ring Sleeve) jack, has an additional metal band on the plug. In addition to carrying the left and right audio signals and ground, the fourth pole carries a microphone or a control signal. This is commonly used in smartphones and other devices that support both headphones and a microphone. The difference between these two types of jacks is mainly in the number of conductive elements or metal bands on the plug. It’s important to note that not all devices support both types of jacks, so it’s important to check the specifications of your device before purchasing headphones or other accessories.
This reference design is for autonomous audio headset switch applications. Some audio headsets have integrated analog microphones. The GND and MIC connections on the audio jack connector may be swapped depending on the manufacturer. This reference design can detect the presence of an analog microphone on the audio headset, detect the pin configuration of the MIC and Ground pins, and switch the system MIC pin to the correct audio jack connector. This allows the audio solution to work seamlessly with headsets from all manufacturers.
The reference design is based on TS3A226AE which is an audio headset switch that detects 3- or 4-pole 3.5mm accessories. For a 4-pole accessory with a microphone, the TS3A226AE also detects the MIC location and routes the microphone and ground signals automatically. The ground signal is routed through a pair of low-impedance ground FETs (60mΩ typical), resulting in minimal impact on audio cross-talk performance.
o VDD range = 2.6V to 4.7V with Ground FET switches (60mΩ typ RON)
o Detection initiated by external trigger pin
o Supports FM signal transmission through the ground FETs
o Reduction of click/pop noise
o THD (Mic): 0.002% Typical
o 8-kV Contact Discharge (IEC 61000-4-2) ESD rating for Sleeve, Ring2 and Tip
This reference design has been tested by TI. The company has also provided additional resources. You can find additional data about the reference design on the company’s website. To read more about this specific reference design click here.