Application Report SLAA454 – June 2010 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Hui Li and David K. Wilson .......................................................................................... Audio Converters ABSTRACT A common feature in most of today's electronic devices – including cell phone, PDAs, notebooks, handheld media players, game systems, etc. – is the provision for connecting to external accessories. The devices therefore include dedicated logic circuitry that can detect not only the presence of an accessory, but also its type. The TLV320AIC33 and TLV320AIC3101/4/5/6 family includes extensive capability to monitor a headphone, microphone (mic), or headset jack, determine if an audio plug has been inserted, and then detect what type of headset is wired to the plug. This application report mainly discusses the headset detection scheme for two different headset output configurations: pseudo-differential (capacitor-less) output, and ac-coupled output. The content of this document applies to the TLV320AIC33 and TLV320AIC3101/4/5/6 family. Contents Headset Plugs/Connection Diagrams .................................................................................... 2 1.1 Part I: Pseudo-Differential (Capacitor-less) Headset Output Configuration ................................ 2 1.2 Part II: AC-Coupled Stereo Headset Output Configuration – Capacitor Interface ......................... 7 2 References ................................................................................................................. 12 Appendix A Example for a Pseudo-Differential (Capacitor-less) Output Configuration ................................ 13 Appendix B Example for an AC-Coupled (Capacitor) Output Configuration ............................................ 14 Appendix C Flowchart for Pseudo-Differential (Capacitor-less) Output Configuration ................................. 15 Appendix D Flowchart for AC-Coupled (Capacitor) Output Configuration ............................................... 18 1 List of Figures ............................................................... ............................................................................ Device with a Pseudo-Differential (Capacitor-less) Headset Output Connection .................................. Circuit Diagram of Detection Scheme for Capacitor-less Interface .................................................. Detection Block for Pseudo-Differential (Capacitor-less) Interface ................................................... Device With an AC-Coupled Stereo Headset Output Connection ................................................... Circuit Diagram of Detection Scheme for Capacitor Interface ....................................................... Detection Block for AC-Coupled (Capacitor) Interface ................................................................ False Detection Due to Overdrawn Current Into Internal Mic ....................................................... Flowchart for Insertion Detection and Headset-Type Detection ..................................................... Flowchart for Hook Button Press Detection and Headset Removal Detection (With Mic) ....................... Flowchart for Headset Removal Detection (Without Mic) ............................................................ Flowchart for Insertion Detection and Headset-Type Detection ..................................................... Flowchart for Hook Button Press Detection and Headset Removal Detection (With Mic) ....................... Flowchart for Headset Removal Detection (Without Mic) ............................................................ Pulse Scheme.............................................................................................................. 1 Different Configurations of 4-Conductor Headset Plug 2 Connection Diagrams for Various Headsets 3 4 5 6 7 8 9 10 11 12 13 14 15 16 SLAA454 – June 2010 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Copyright © 2010, Texas Instruments Incorporated 2 2 3 3 4 7 7 8 11 15 16 17 18 19 19 20 1 Headset Plugs/Connection Diagrams 1 www.ti.com Headset Plugs/Connection Diagrams g Stereo s Cellular g m Stereo + Cellular g m s s Stereo Headphone s Mono Headphone With Mic s Stereo Headphone With Mic m = mic s = stereo g = ground/vgnd Figure 1. Different Configurations of 4-Conductor Headset Plug s s s g g g 16-64 W s >1 kW s ~100 W ~100 W m m Stereo + Cellular g m s s Cellular g m s Stereo g s s Figure 2. Connection Diagrams for Various Headsets 1.1 Part I: Pseudo-Differential (Capacitor-less) Headset Output Configuration Figure 3 shows one configuration of the device that enables detection and determination of headset type when a pseudo-differential (capacitor-less) stereo headphone output connection is used. Note that for best results, it is recommended to select a MICBIAS value as high as possible, and to program the output driver common-mode level at a 1.35-V or 1.5-V level. 2 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Copyright © 2010, Texas Instruments Incorporated SLAA454 – June 2010 Headset Plugs/Connection Diagrams www.ti.com MICBIAS g Stereo s s MICDET AVDD To Detection Block MIC3(L/R) Cellular g s m HPLOUT Stereo + Cellular g s m s HPROUT m = mic s = ear speaker g = ground/midbias To Detection Block HPCOM 1.35 V Figure 3. Device with a Pseudo-Differential (Capacitor-less) Headset Output Connection Figure 4 demonstrates the internal circuitry that implements the detection logic. The detection block circled in red consists of three main components – comparator A, B, and C. Various Headset Connections s s s Internal Circuitry HPLOUT Dspk1 g g g Dvgnd HPCOM s s HPROUT SW3 VSS Dspk2 Mono V1 SW4 Mic PGA MIC3(L/R) m m m V1 VDD Stereo/ Hook_det MICDET Headset Detect V2 MICBIAS SW1 Headset Detect SW2 MICBIAS (2.5/3.3 V) VDD DET_PULSE Figure 4. Circuit Diagram of Detection Scheme for Capacitor-less Interface SLAA454 – June 2010 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Copyright © 2010, Texas Instruments Incorporated 3 Headset Plugs/Connection Diagrams 1.1.1 www.ti.com Detection Block, Capacitor-less Interface HPLOUT Internal Circuitry ··· ··· HPCOM Comparator A HPROUT MIC3(L/R) Mono V1 SW4 VDD Comparator B V1 Stereo/ Hook_det MICDET Headset Detect V2 MICBIAS Comparator C ··· External Connections Figure 5. Detection Block for Pseudo-Differential (Capacitor-less) Interface 4 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Copyright © 2010, Texas Instruments Incorporated SLAA454 – June 2010 Headset Plugs/Connection Diagrams www.ti.com Comparator C is used to detect headset insertion and removal. Headset insertion and removal detection is always active inside device. MICDET < V2 Insertion detected MICDET > V2 No insertion Comparator B is used to detect the type of headset inserted. Headset type detection becomes active only when the headset is inserted and detected. MICDET > V1 Headset with mic MICDET < V1 Headset without mic Comparator B is also used to detect hook button press. However, button press detection becomes active only when headset with mic is detected. Given headset with mic is already detected: MICDET > V1 No button press MICDET < V1 Button press detected Comparator A is used to differentiate mono headset with mic from stereo headset with mic. 1.1.2 HPROUT > V1 Mono headset with mic HPROUT < V1 Stereo headset with mic How to Determine the Comparator Threshold V1 and V2 (Capacitor-less Interface) MICBIAS V2 V1 REF V1 = (MICBIAS - ref ) V2 = (MICBIAS - ref ) 3 ´ + ref 46 43 ´ + ref 46 ref = HPCOM MICBIAS varies with detection mode 1.1.3 How Does the Bias Voltage Vary With Detection Mode? If MICBIAS is turned off or if headset insertion is not detected, then MICBIAS = DVDD If MICBIAS is turned on and if headset insertion is detected, then MICBIA= Mic_bias SLAA454 – June 2010 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Copyright © 2010, Texas Instruments Incorporated 5 Headset Plugs/Connection Diagrams 1.1.4 www.ti.com Detection Sequence – Capacitor-less Interface Enable headset detection scheme (Page 0, Reg 13, D7) and set Capacitor-less interface (Page 0, Reg 14, D7 = 0) • Detect insertion (with headset detection scheme enabled, headset insertion detection is always active inside device) Insertion detected: 43 43 MICDET < (MICBIAS - ref) ´ + ref = (DVDD - ref) ´ + ref 46 46 • No Insertion: MICDET > (MICBIAS - ref) ´ • 43 43 + ref = (DVDD - ref) ´ + ref 46 46 Headset type detection (ONLY active when headset is inserted and detected) Headset with mic: 3 3 MICDET > (MICBIAS - ref) ´ + ref = (Mic_bias - ref) ´ + ref 46 46 Headset without mic: MICDET < (MICBIAS - ref) ´ • 3 3 + ref = (Mic_bias - ref) ´ + ref 46 46 Button press detection (button press detection becomes active ONLY when headset with mic is detected) No button push: 3 3 MICDET > (MICBIAS - ref) ´ + ref = (Mic_bias - ref) ´ + ref 46 46 Button push detected: MICDET < (MICBIAS - ref) ´ • 3 3 + ref = (Mic_bias - ref) ´ + ref 46 46 Headset removal detection (With headset detection scheme enabled, removal detection is always active inside device.) Headset removed: 43 43 MICDET < (MICBIAS - ref) ´ + ref = (Mic_bias - ref) ´ + ref 46 46 Insertion detected: MICDET > (MICBIAS - ref) ´ 6 43 43 + ref = (Mic_bias - ref) ´ + ref 46 46 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Copyright © 2010, Texas Instruments Incorporated SLAA454 – June 2010 Headset Plugs/Connection Diagrams www.ti.com 1.2 Part II: AC-Coupled Stereo Headset Output Configuration – Capacitor Interface MICBIAS g Stereo s s MICDET AVDD To Detection Block MIC3(L/R) Cellular g s m HPLOUT Stereo + Cellular g s m s HPROUT m = mic s = ear speaker g = ground/midbias Figure 6. Device With an AC-Coupled Stereo Headset Output Connection Figure 7 shows the detection logic implemented by the detection block circled in red. The detection block consists of three main components – comparator A, B, and C. Various Headset Connections s s s HPLOUT Internal Circuitry Dspk1 g g VDD g GND s s SW4 HPROUT Dspk2 Mono V1 Mic PGA MIC3(L/R) m m V1 m Stereo/ Hook_det MICDET Headset Detect V2 MICBIAS SW1 Headset Detect SW2 MICBIAS (2.5/3.3 V) VDD DET_PULSE Figure 7. Circuit Diagram of Detection Scheme for Capacitor Interface SLAA454 – June 2010 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Copyright © 2010, Texas Instruments Incorporated 7 Headset Plugs/Connection Diagrams 1.2.1 www.ti.com Detection Block – Capacitor Interface HPLOUT Internal Circuitry ··· VDD GND SW4 Comparator A HPROUT ··· Mono V1 Comparator B MIC3(L/R) V1 Stereo/ Hook_det MICDET Headset Detect V2 MICBIAS Comparator C ··· External Connections Figure 8. Detection Block for AC-Coupled (Capacitor) Interface 8 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Copyright © 2010, Texas Instruments Incorporated SLAA454 – June 2010 Headset Plugs/Connection Diagrams www.ti.com Comparator C is used to detect headset insertion and removal. Headset insertion and removal detection is always active inside device. MICDET < V2 Insertion detected MICDET > V2 No insertion Comparator B is used to detect the type of headset inserted. Headset type detection becomes active only when the headset is inserted and detected. MICDET > V1 Headset with mic MICDET < V1 Headset without mic Comparator B is also used to detect hook button press. However button press detection becomes active only when headset with mic is detected. Given headset with mic is already detected: MICDET > V1 No button press MICDET < V1 Button press detected Comparator A is used to differentiate mono headset with mic from stereo headset with mic. 1.2.2 HPROUT > V1 Mono headset with mic HPROUT < V1 Stereo headset with mic How to Determine the Comparator Threshold V1 and V2 – Capacitor Interface MICBIAS V2 V1 REF V1 = (MICBIAS - ref ) V2 = (MICBIAS - ref ) 3 ´ + ref 46 43 ´ + ref 46 ref = VSS = 0 V MICBIAS varies with detection mode 1.2.3 How Does the Bias Voltage Change With Detection Mode? If MICBIAS is turned off or if headset insertion is not detected, then MICBIAS = DVDD If MICBIAS is turned on and if headset insertion is detected, then MICBIAS = Mic_bias SLAA454 – June 2010 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Copyright © 2010, Texas Instruments Incorporated 9 Headset Plugs/Connection Diagrams 1.2.4 www.ti.com Detection Sequence – Capacitor Interface Enable headset detection scheme (Page 0, Reg 13, D7) and set AC-coupled interface (page 0, Reg 14, D7 = 1) • Detect insertion (With headset detection scheme enabled, headset insertion detection is always active inside device.) Insertion detected: • MICBIAS < (MICBIAS - ref) ´ 43 43 + ref = DVDD ´ 46 46 No insertion: MICBIAS > (MICBIAS - ref) ´ • 43 43 + ref = DVDD ´ 46 46 Headset type detection (only active when headset is inserted and detected) Headset with mic: 3 3 MICBIAS > (MICBIAS - ref)× + ref = Mic_bias ´ 46 46 Headset without mic: MICBIAS < (MICBIAS - ref) × • 3 3 + ref = Mic_bias ´ 46 46 Button press detection (button press detection becomes active only when headset with mic is detected) No button push: 3 3 MICBIAS > (MICBIAS - ref) × + ref = Mic_bias ´ 46 46 Button push detected: MICBIAS < (MICBIAS - ref) × • 3 3 + ref = Mic_bias ´ 46 46 Headset removal detection (with headset detection scheme enabled, removal detection is always active inside device.) Headset removed: 43 43 MICBIAS > (MICBIAS - ref) × + ref = Mic_bias ´ 46 46 Insertion detected: MICBIAS < (MICBIAS - ref) × 43 43 + ref = Mic_bias ´ 46 46 43 ö æ 3 or ç ÷ 46 46 è ø are determined by the on-chip resistance. A mismatch of Note: The ratio above on-chip resistance can cause a variation in the ratio by ±10%. 10 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Copyright © 2010, Texas Instruments Incorporated SLAA454 – June 2010 Headset Plugs/Connection Diagrams www.ti.com 1.2.5 Why Does False Detection Occur When no External Microphone is Inserted? VDD High Z when closed S1 Ix < 350uA V_bias Micbias(2.5/3.3 V) 2K 2K Internal Mic + Comparator for insertion detection V2 GND VJack for external Mic (simplified) GND Figure 9. False Detection Due to Overdrawn Current Into Internal Mic In both capacitor-less and capacitor interface, Reg 14/D6 = 0. Under this condition, bias voltage V_bias adjusts its value based on the detection status: With Reg14/D6 = 0 Before detection V_bias = VDD After detection V_bias = Micbias A portable device like a cell phone not only provides a jack for an external mic, but also has an internal mic embedded inside the device. The TLC320AIC33 and TLC320AIC3101/4/5/6 family device is designed in a way such that it can only accommodate a current flow of no more than 350 µA into the internal mic. A false detection occurs if the internal mic is drawing more than 350-µA current. The paragraph below gives a detailed explanation of the false detection. With Reg14/D6 =0, V_bias is set at VDD when no insertion is detected. That is, switch S1 is switched on when no insertion is detected. Current flow into the Internal mic Ix has to be less than 350 µA in order to keep V_bias on a level such that V≥V2. With V≥V2, the comparator outputs a logic 0 which indicates no insertion is detected. However, false detection occurs when the internal mic draws more than 350-µA current. The extra current drawn by the internal mic pulls V_bias down so that V≤V2. With V≤V2, comparator outputs a logic 1 which indicates insertion is detected. Once this false detection occurs, S1 is switched off and V_bias is set at Micbias instead of VDD. The new bias voltage sets V≥V2 again and comparator outputs a logic 0 which implies no detection again. The output of comparator therefore switches between 0 and 1 due to the extra current drawn by the internal mic. To summarize, the current drawn by the internal mic has to be less than 350 µA in order to avoid false detection. When the current Ix is larger than 350 µA, the comparator generates a false detection even when nothing is actually inserted into the mic jack. A good check in a real application is to double-check the current drawn by the internal mic and make sure that it is under 350 µA. SLAA454 – June 2010 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Copyright © 2010, Texas Instruments Incorporated 11 References 2 www.ti.com References 1. http://www.india.ti.com/cgi-bin/mstc/twiki/bin/view/DAPIND/AIC33Apps 2. TLV320AIC3100, Low Power Stereo CODEC with integrated Mono Class-D Speaker Amplifier data sheet (SLOS545) 12 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Copyright © 2010, Texas Instruments Incorporated SLAA454 – June 2010 www.ti.com Appendix A Example for a Pseudo-Differential (Capacitor-less) Output Configuration DVDD = 2 V Mic_bias = 3.3 V Ref = HPRCOM = 1.3 V • Before insertion, set Bias = DVDD – HPCOM = 2.0 V – 1.3 V = 0.7 V 43 43 Insertion detected: Mic_detect < Bias × + Ref = 0.7 × + 1.3 = 1.95 V 46 46 43 43 No insertion: Mic_detect > Bias × + Ref = 0.7 × + 1.3 = 1.95 V 46 46 • Headset type detection, set Bias = Mic_bias – HPCOM = 3.3 – 1.3 = 2.0 V 3 3 Headset with Mic: Mic_detect > Bias × + Ref = 2.0 × + 1.3 = 1.43 V 46 46 3 3 Headset without Mic: Mic_detect < Bias × + Ref = 2.0 × + 1.3 = 1.43 V 46 46 • Hook button press detection, set Bias = Mic_bias – HPCOM =3.3 –1.3 = 2.0 Button press detection is active only when headset with mic has been detected. 3 3 No button push: Mic_detect > Bias × + Ref = 2.0 × + 1.3 = 1.43 V 46 46 3 3 Button push detected: Mic_detect < Bias × + Ref = 2.0 × + 1.3 = 1.43 V 46 46 • Headset removal detection, set Bias = Mic_bias – HPCOM = 3.3 – 1.3 = 2 V 43 43 Headset removed: Mic_detect > Bias × + Ref = 2.0 × + 1.3 = 3.17 V 46 46 43 43 Insertion detected: Mic_detect < Bias × + Ref = 2.0 × + 1.3 = 3.17 V 46 46 SLAA454 – June 2010 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Copyright © 2010, Texas Instruments Incorporated 13 www.ti.com Appendix B Example for an AC-Coupled (Capacitor) Output Configuration DVDD = 2 V Mic_bias = 3.3 V Ref = VSS = 0 V • Before insertion, set Bias = DVDD = 2 V 43 43 Insertion detected: Mic_detect < Bias × + Ref = 2.0 × + 0 = 1.87 V 46 46 43 43 No insertion: Mic_detect > Bias × + Ref = 2.0 × +0 = 1.87 V 46 46 14 • Headset type detection, set Bias = Mic_bias = 3.3 V 3 3 Headset with Mic: Mic_detect > Bias × + Ref = 3.3 × + 0 = 0.22 V 46 46 3 3 Headset without Mic: Mic_detect < Bias × + Ref = 3.3 × + 0 = 0.22 V 46 46 • Button press detection, set Bias = Mic_bias = 3.3 V Button press detection is active only when headset with mic has been detected. 3 3 No button push: Mic_detect > Bias × + Ref = 3.3 × + 0 = 0.22 V 46 46 3 3 Button push detected: Mic_detect < Bias × + Ref = 3.3 × + 0 = 0.22 V 46 46 • Headset removal detection, set Bias = Mic_bias = 3.3 V. 43 43 Headset removed: Mic_detect > Bias × + Ref = 3.3 × + 0 = 3.08 V 46 46 43 43 Insertion detected: Mic_detect < Bias × + Ref = 3.3 × + 0 = 3.08 V 46 46 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Copyright © 2010, Texas Instruments Incorporated SLAA454 – June 2010 www.ti.com Appendix C Flowchart for Pseudo-Differential (Capacitor-less) Output Configuration Reset (sw2 = open) Close sw3 Yes Is Micbias on? No Open sw1 Close sw1 Is Headset_Detect high? Open sw2 No Jack is taken out Yes Send and interrupt to processor and set bit in control Reg Is Stereo HS high? Headset insertion is detected Yes No Close sw4 No Is Cell HS high? Yes Set bit indicating Stereo Cell HS. Open sw1 Set bit indicating Cell HS. Open sw1, sw4 Set bit indicating Stereo HS. Open sw1 HS with Mic Stereo HS Jack taken out F0040-01 Figure 10. Flowchart for Insertion Detection and Headset-Type Detection SLAA454 – June 2010 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Copyright © 2010, Texas Instruments Incorporated 15 Appendix C www.ti.com The insertion detection and the headset-type detection are evaluated in Figure 10 HS with Mic Is Dvgnd on? No Yes Switch on Micbias. Open sw3 Is Micbias on? Yes No Close sw2 Give DET_PULSE No Is Headset_DETECT low at the end of DET_PULSE? Is Hook_det high at the end of DET_PULSE? Is Hook_det high? Yes Yes Yes Jack taken out No Infer it as hook button press send an interrupt to processor No Is Headset_Detect low? No Yes Jack taken out F0041-01 Figure 11. Flowchart for Hook Button Press Detection and Headset Removal Detection (With Mic) If Dvgnd (VGND driver) is on, Micbias is switched on in order to do the hook button press detection and plug removal detection. Power due to Micbias is insignificant as compared to speaker power. If both Dvgnd and Micbias are off, pulse scheme which takes less than 50 µA is used to complete the detection. Detection is done at the end of high period of pulse. 16 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Copyright © 2010, Texas Instruments Incorporated SLAA454 – June 2010 Appendix C www.ti.com Stereo HS No Yes Is Dvgnd on? No Yes Close sw2 Give DET_PULSE Switch on Micbias. Open sw3 Is Headset_DETECT low at the end of DET_PULSE? Is Headset_Detect low? Jack taken out No Yes Jack taken out No F0042-01 Figure 12. Flowchart for Headset Removal Detection (Without Mic) If Dvgnd (VGND driver) is on, Micbias is switched on in order to do the plug removal detection. Power due to Micbias is insignificant as compared to speaker power. If Dvgnd is off, pulse scheme which takes less than 50 µA is used to complete the detection. Detection is done at the end of the high period of the pulse. SLAA454 – June 2010 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Copyright © 2010, Texas Instruments Incorporated 17 www.ti.com Appendix D Flowchart for AC-Coupled (Capacitor) Output Configuration Reset (sw2 = open) Is Micbias on? Yes No Open sw1 Close sw1 Is Headset_Detect high? Open sw2 No Jack is taken out Yes Send and interrupt to processor and set bit in control Reg Is Stereo HS high? Headset insertion is detected Yes No Close sw4 No Is Cell HS high? Yes Set bit indicating Stereo Cell HS. Open sw1 Set bit indicating Cell HS. Open sw1, sw4 Set bit indicating Stereo HS. Open sw1 HS with Mic Stereo HS Jack taken out F0043-01 Figure 13. Flowchart for Insertion Detection and Headset-Type Detection 18 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Copyright © 2010, Texas Instruments Incorporated SLAA454 – June 2010 Appendix D www.ti.com HS with Mic Is Micbias on? Yes No Close sw2 Give DET_PULSE No Is Headset_DETECT low at the end of DET_PULSE? Is Hook_det high at the end of DET_PULSE? Is Hook_det high? Yes Yes Yes Jack taken out Infer it as hook button press send an interrupt to processor No No Is Headset_Detect low? No Yes Jack taken out F0044-01 Figure 14. Flowchart for Hook Button Press Detection and Headset Removal Detection (With Mic) Stereo HS Close sw2 Give DET_PULSE Yes Is Headset_DETECT low at the end of DET_PULSE? Jack taken out No F0045-01 Figure 15. Flowchart for Headset Removal Detection (Without Mic) Pulse Scheme SLAA454 – June 2010 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Copyright © 2010, Texas Instruments Incorporated 19 Appendix D www.ti.com Detection Done at the End of Pulse 15 ms DET_PULSE 0.5 ms T0464-01 Figure 16. Pulse Scheme DET_PULSE, which is generated using an internal oscillator, is used for hook button detection. DET_PULSE period is 0.5 ms with high time of 15 µs. 20 Headset Detection for TLV320AIC33 and TLV320AIC3101/4/5/6 Family Copyright © 2010, Texas Instruments Incorporated SLAA454 – June 2010 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. 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