1page.title=3.5 mm Headset Jack: Device Specification
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19<div id="qv-wrapper">
20  <div id="qv">
21    <h2>In this document</h2>
22    <ol id="auto-toc">
23    </ol>
24  </div>
25</div>
26
27
28<p>To achieve compatibility with the <a href="plug-headset-spec.html">3.5 mm plug
29headset specification</a>, devices that include a 4 conductor 3.5 mm audio jack
30must meet the following specifications. For Android compatibility requirements,
31refer to the <em>Analog audio ports</em> section of the <a
32href="{@docRoot}compatibility/android-cdd.html#7_8_audio">Android CDD</a>.</p>
33
34<h2 id="headset_jack_functions">Functions</h2>
35
36<table>
37 <tr>
38    <th>Function</th>
39    <th>Device Support</th>
40 </tr>
41 <tr>
42    <td>Stereo Audio Out</td>
43    <td>Required</td>
44 </tr>
45 <tr>
46    <td>Audio in (Mic)</td>
47    <td>Required</td>
48 </tr>
49 <tr>
50    <td>Ground</td>
51    <td>Required</td>
52 </tr>
53</table>
54
55<h2 id="software_mapping">Software mapping</h2>
56
57<table>
58 <tr>
59    <th style="width:33%">Function</th>
60    <th style="width:33%">Device Support</th>
61    <th style="width:33%">Description</th>
62 </tr>
63 <tr>
64    <td>Function A control event</td>
65    <td>Required</td>
66    <td>Input event: <code>KEY_MEDIA</code>
67<p>Android key: <code>KEYCODE_HEADSETHOOK<code></p></td>
68 </tr>
69 <tr>
70    <td>Function D control event</td>
71    <td>Required</td>
72    <td>Input event: <code>KEY_VOICECOMMAND</code>
73<p>Android key: <code>KEYCODE_VOICE_ASSIST</code></p></td>
74 </tr>
75 <tr>
76    <td>Function B control event</td>
77    <td>Required</td>
78    <td>Input event: <code>KEY_VOLUMEUP</code>
79<p>Android key: <code>VOLUME_UP</code></p></td>
80 </tr>
81 <tr>
82    <td>Function C control event</td>
83    <td>Required</td>
84    <td>Input event: <code>KEY_VOLUMEDOWN</code>
85<p>Android key: <code>VOLUME_DOWN</code></p></td>
86 </tr>
87 <tr>
88    <td>Headset insertion detection</td>
89    <td>Required</td>
90    <td>Input event: <code>SW_JACK_PHYSICAL_INSERT 7</code></td>
91 </tr>
92 <tr>
93    <td rowspan="2">Headset type detection</td>
94    <td>Mic</td>
95    <td>Input event: <code>SW_MICROPHONE_INSERT 4</code></td>
96 </tr>
97 <tr>
98    <td>No Mic</td>
99    <td>Input event: <code>SW_HEADPHONE_INSERT 2</code></td>
100 </tr>
101 <tr>
102    <td rowspan="2">Headset speaker impedance</td>
103    <td>Required Headphone (low)</td>
104    <td>Failure mode is to indicate headphones so limitation would be on</td>
105 </tr>
106 <tr>
107    <td>Required Line In (high)</td>
108    <td>Input event: <code>SW_LINEOUT_INSERT 6</code></td>
109 </tr>
110</table>
111
112<h2 id="mechanical11">Mechanical</h2>
113
114<table>
115 <tr>
116    <th style="width:33%">Function</th>
117    <th style="width:33%">Device Support</th>
118    <th style="width:33%">Description</th>
119 </tr>
120 <tr>
121    <td>4 conductor 3.5 mm jack</td>
122    <td>Required</td>
123    <td></td>
124 </tr>
125 <tr>
126    <td>CTIA pinout order (LRGM)</td>
127    <td>Required</td>
128    <td>3 Pin & Mono Plug Compatible</td>
129 </tr>
130 <tr>
131    <td>OMTP pinout order (LRMG)</td>
132    <td>Optional but strongly recommended</td>
133    <td></td>
134 </tr>
135 <tr>
136    <td>Headset detect sequence</td>
137    <td>Required</td>
138    <td>Plug insert notification must be triggered only after all contacts on
139    plug are touching their relevant segments (this prevents unreliable headset
140    detection due to slow insertion.</td>
141 </tr>
142</table>
143
144<h2 id="electrical12">Electrical</h2>
145
146<h3 id="general">General</h3>
147
148<table>
149 <tr>
150    <th style="width:33%">Function</th>
151    <th style="width:33%">Device Support</th>
152    <th style="width:33%">Notes</th>
153 </tr>
154 <tr>
155    <td>Maximum output voltage drive</td>
156    <td>150mV</td>
157    <td>&gt;= 150mV on 32 ohm
158<p>Test conditions: EN50332-2</p></td>
159 </tr>
160 <tr>
161    <td>Mic bias resistance</td>
162    <td>Required</td>
163    <td>Flexible on detection method used and microphone bias resistor
164    selection. Require that all button resistance value ranges specified below
165    be detected and related to their respective function</td>
166 </tr>
167 <tr>
168    <td>Mic bias voltage</td>
169    <td>1.8V - 2.9V</td>
170    <td>To guarantee compatibility to common microphone capsules.</td>
171 </tr>
172</table>
173
174<h3 id="function_impedance_and_threshold_detection">Function impedance and
175threshold detection</h3>
176
177<p>Devices must detect the following resistor ladder on the accessories. The
178accessories will be tested to the standardized circuit diagram in the diagram
179illustrated earlier (Reference Headset Test Circuit) where the total impedance
180is measured from MIC terminal to GND when a button is pressed with 2.2V mic
181bias applied through 2.2 kOhm resistor. This is the same effective resistance
182as the button detection circuit with the microphone in parallel with the button
183resistor.</p>
184
185<table>
186 <tr>
187    <th style="width:40%">Button Impedance Level</th>
188    <th style="width:20%">Device Support</th>
189    <th style="width:40%">Notes</th>
190 </tr>
191 <tr>
192    <td>70 ohm or less</td>
193    <td>Required</td>
194    <td>[Function A]</td>
195 </tr>
196 <tr>
197    <td>110 - 180 ohm</td>
198    <td>Required</td>
199    <td>[Function D]</td>
200 </tr>
201 <tr>
202    <td>210 - 290 ohm</td>
203    <td>Required</td>
204    <td>[Function B]</td>
205 </tr>
206 <tr>
207    <td>360 - 680 ohm</td>
208    <td>Required</td>
209    <td>[Function C]</td>
210 </tr>
211 </table>
212
213 <table>
214 <tr>
215    <th style="width:40%">Headset Speaker Impedance Level</th>
216    <th style="width:20%">Device Support</th>
217    <th style="width:40%">Notes</th>
218 </tr>
219 <tr>
220    <td>Low Threshold Detection</td>
221    <td>Required</td>
222    <td>Headphone (low) &lt; 1 Kohm</td>
223 </tr>
224 <tr>
225    <td>High Threshold Detection</td>
226    <td>Required</td>
227    <td>Line In (high) &gt; 5 Kohm</td>
228 </tr>
229</table>
230
231 <table>
232 <tr>
233    <th style="width:40%">4-Segment Plug Detection Resistance (between 3rd and 4th segment)</th>
234    <th style="width:20%">Device Support</th>
235    <th style="width:40%">Notes</th>
236 </tr>
237 <tr>
238    <td>4-Segment Plug Threshold</td>
239    <td>Required</td>
240    <td>Resistance &gt;= 100 ohms</td>
241 </tr>
242 <tr>
243    <td>3-Segment Plug Threshold</td>
244    <td>Required</td>
245    <td>Resistance &lt; 100 ohms</td>
246 </tr>
247</table>
248