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SCDA014–March 2016
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Detecting Selfie Sticks Using TI Audio Jack Switches TS3A227E and
TS3A225E
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Application Report
SCDA014–March 2016
Detecting Selfie Sticks Using TI Audio Jack Switches
TS3A227E and TS3A225E
Jamie Zhang, Adam Torma
ABSTRACT
Selfie sticks are becoming as common of a smart phone accessory as a pair of headphones. Because of
the selfie stick’s increasing popularity, smart phone manufacturers need to be able to accommodate the
accessory. This report describes the procedure required for a smart phone to detect when a selfie stick
accessory is inserted into a smart phone's audio jack receptacle using TI audio jack switches TS3A227E
and TS3A225E. It shows how these devices respond to common selfie-stick implementations and how to
adjust the audio jack switch’s register settings to accommodate both traditional audio accessories as well
as the new selfie stick accessory.
Contents
1 Selfie Stick Schematic Overview .......................................................................................... 2
2 TS3A227E and TS3A225E Selfie Stick and Accessory Detection Overview........................................ 3
3 How to Support a Selfie Stick Using TI’s Audio Jack Switches........................................................ 5
4 Conclusion .................................................................................................................. 10
Appendix A ....................................................................................................................... 11
List of Figures
1 Typical Selfie Stick Schematic............................................................................................. 2
2 TS3A227E Application Circuit With Closed Circuit From Ring2 To Tip Made With Headphone Accessory..... 3
3 TS3A227E Application Circuit With Open Circuit From Ring2 To Tip Schematic With Selfie Stick Inserted.... 3
4 TS3A227E Switch State After Manually Configuring Internal Switch Network to Support Selfie Stick........... 4
5 TS3A227E Switch State After Detecting a 4-Pole OMTP Headset ................................................... 4
6 Selfie Stick Usage Logic Flow ............................................................................................. 5
7 TS3A227E Switch State After Detecting a 3-Pole Headphone........................................................ 6
8 TS3A227E Switch State After Manually Configuring Internal Switch Network to Support Selfie Stick........... 7
9 Microphone Bias is High With Selfie Stick Inserted Into the Audio Jack Receptacle............................... 8
10 Microphone Bias is Low With 3-pole Headphones Inserted Into the Audio Jack Receptacle..................... 8
11 Typical Application Schematic With Headphone Accessory.......................................................... 12
12 TS3A227E Default Switch State With no Accessory Inserted ....................................................... 12
13 TS3A227E Switch State During Detection.............................................................................. 13
14 TS3A227E Switch State After Detecting a 3-Pole Headphone ...................................................... 13
15 TS3A227E Switch State After Detecting a 4-Pole OMTP Headset.................................................. 14
List of Tables
1 Audio Jack Plug Configurations .......................................................................................... 11
