LM4949 Stereo Class D Audio Subsystem with OCL Headphone Amplifier General Description Key Specifications The LM4949 is a fully integrated audio subsystem designed for stereo cell phone applications. The LM4949 combines a 2.5W stereo Class D amplifier plus a separate 190mW stereo headphone amplifier, volume control, and input mixer into a single device. The filterless class D amplifiers deliver 1.19W/channel into an 8Ω load with < 1% THD+N from a 5V supply. The headphone amplifier features National’s Output Capacitor-less (OCL) architecture that eliminates the output coupling capacitors required by traditional headphone amplifiers. Additionally, the headphone amplifiers can be configured with capacitively coupled (CC)loads, or used to drive an external headphone amplifier. When configured for an external amplifier, the VDD/2 output (VOC) controls the external amplifier’s shutdown input. For improved noise immunity, the LM4949 features fully differential left, right and mono inputs. The three inputs can be mixed/multiplexed to either the speaker or headphone amplifiers. The left and right inputs can be used as separate single-ended inputs, mixing multiple stereo audio sources. The mixer, volume control, and device mode select are controlled through an I2C compatible interface. Output short circuit and thermal shutdown protection prevent the device from being damaged during fault conditions. Superior click and pop suppression eliminates audible transients on power-up/down and during shutdown. j Efficiency VDD = 3.6V, 400mW into 8Ω j Efficiency VDD = 5V, 1W into 8Ω j Quiescent Power Supply Current @ 3.6V 86.5% 87.4% 9.36mA j Power Output at VDD = 5V Speaker: RL = 4Ω, THD+N ≤ 1% RL = 8Ω, THD+N ≤ 1% RL = 4Ω, THD+N ≤ 10% 2W 1.19W 2.5W Headphone: RL = 16Ω, THD+N ≤ 1% RL = 32Ω, THD+N ≤ 1% 153mW 89mW j Shutdown Current 0.1µA Features n n n n n n n n n n n n Output Short Circuit Protection Thermal Shutdown Stereo filterless Class D operation Selectable OCL/CC Headphone Drivers RF Suppression I2C Control Interface 32-step digital volume control Independent Speaker and Headphone Gain Settings Minimum external components Click and Pop suppression Micro-power shutdown Available in space-saving 25 bump µSMD package Applications n Mobile phones n PDAs n Laptops Boomer ® is a registered trademark of National Semiconductor Corporation. © 2006 National Semiconductor Corporation DS202001 www.national.com LM4949 Stereo Class D Audio Subsystem with OCL Headphone Amplifier September 2006 LM4949 Typical Application 202001C6 FIGURE 1. Typical Audio Amplifier Application Circuit www.national.com 2 LM4949 Connection Diagrams TL Package 2.68mm x 2.68mm x 0.6mm 202001C7 Top View Order Number LM4949TL See NS Package Number TLA25JJA LM4949TL Marking 202001C0 Top View XY — 2 digit datecode TT — Die traceability 3 www.national.com LM4949 Absolute Maximum Ratings (Note 2) Thermal Resistance θJA If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage (Note 1) Storage Temperature Operating Ratings 6.0V Temperature Range −65˚C to +150˚C TMIN ≤ TA ≤ TMAX −0.3V to VDD +0.3V Input Voltage Power Dissipation (Note 3) Internally Limited ESD Susceptibility (Note 4) 2000V ESD Susceptibility (Note 5) 200V Junction Temperature 35.1˚C/W −40˚C ≤ TA ≤ +85˚C 2.7V ≤ VDD≤ 5.5V Supply Voltage (VDD, VDDLS, VDDHP) 2.4V ≤ I2CVDD≤ 5.5V I2C Voltage (I2CVDD) 150˚C Electrical Characteristics VDD = 3.0V (Notes 1, 2) The following specifications apply for AV = 0dB, RL(SP) = 15µH + 8Ω + 15µH, RL(HP) = 32Ω, f = 1kHz unless otherwise specified. Limits apply for TA = 25˚C. LM4949 Symbol IDD Parameter Supply Current Conditions Shutdown Supply Current VOS Output Offset Voltage POUT Output Power www.national.com Limit Units (Limits) (Note 6) (Notes 7, 8) LS Mode Stereo Mono 6 4.5 8.75 mA (max) mA OCL HP Mode Stereo Mono 5.0 4.3 6.5 mA (max) mA CC HP Mode Stereo Mono 4.0 3.3 5.25 mA (max) mA 0.03 2 µA (max) Speaker (mode 1) OCL HP (mode 1) 8.9 5.6 48.9 24.5 mV (max) mV (max) LS Mode, f = 1 kHz RL = 4Ω, THD+N = 10% RL = 4Ω, THD+N = 1% RL = 8Ω, THD+N = 10% RL = 8Ω, THD+N = 1% 820 662 515 415 340 mW mW mW mW (min) OCP HP Mode, f = 1 kHz RL = 16Ω, THD+N = 10% RL = 16Ω, THD+N = 1% RL = 32Ω, THD+N = 10% RL = 32Ω, THD+N = 1% 62.5 50 37.5 30.3 mW mW mW mW CC HP Mode, f = 1 kHz RL = 16Ω, THD+N = 10% RL = 16Ω, THD+N = 1% RL = 32Ω, THD+N = 10% RL = 32Ω, THD+N = 1% 63 50 38 30 mW mW mW mW (min) Stereo LS + HP Mode ISD Typical 4 8.6 mA LM4949 Symbol Parameter Conditions Typical Limit (Note 6) (Notes 7, 8) Units (Limits) Differential Mode, f = 1kHz THD+N Total Harmonic Distortion + Noise HP Mode, RL = 16Ω, POUT = 35mW OCL CC 0.015 0.012 % % HP Mode, RL = 32Ω, POUT = 20mW OCL CC 0.017 0.018 % % LS Mode RL = 4Ω, POUT = 300mW RL = 8Ω, POUT = 150mW 0.023 0.02 % % HP Mode, RL = 16Ω, POUT = 35mW OCL CC 0.023 0.017 % % HP Mode, RL = 32Ω, POUT = 20mW OCL CC 0.019 0.013 % % LS Mode RL = 4Ω, POUT = 300mW RL = 8Ω, POUT = 150mW 0.05 0.03 % % Single-Ended Input Mode, f = 1kHz THD+N Total Harmonic Distortion + Noise Differential Input, A-weighted, Input Referred eN η Noise Efficiency Mono Input OCL CC LS 16.4 15.5 43 µV µV µV All Inputs ON OCL CC LS 29.8 29.2 46.6 µV µV µV Single-Ended Input, A-weighted, Input Referred Stereo Input OCL CC LA 12 11 45 µV µV µV All Inputs ON OCL CC LS 23.7 22.9 52 µV µV µV LS Mode, POUT = 400mW, RL = 8Ω 85.3 % 84.7 dB LS Mode, f = 1kHz, RL = 8Ω, VIN = 1VP-P Xtalk Crosstalk Differential Input Mode OCL HP Mode, f = 1kHz, RL = 32Ω, VIN = 1VP-P Differential Input Mode 68 dB TON Turn on Time CC Mode OCL Mode LS Mode 68 14 29 ms ms ms TOFF Turn off Time From any mode 683 ms 5 www.national.com LM4949 Electrical Characteristics VDD = 3.0V (Notes 1, 2) The following specifications apply for AV = 0dB, RL(SP) = 15µH + 8Ω + 15µH, RL(HP) = 32Ω, f = 1kHz unless otherwise specified. Limits apply for TA = 25˚C. (Continued) LM4949 Electrical Characteristics VDD = 3.0V (Notes 1, 2) The following specifications apply for AV = 0dB, RL(SP) = 15µH + 8Ω + 15µH, RL(HP) = 32Ω, f = 1kHz unless otherwise specified. Limits apply for TA = 25˚C. (Continued) LM4949 Symbol ZIN Parameter Input Impedance Conditions Maximum Gain Minimum Gain Typical Limit (Note 6) (Notes 7, 8) Units (Limits) 24.8 222.7 kΩ kΩ –57 18 dB dB Step 0 Differential Input Single-Ended Input 6 12 dB dB Step 1 Differential Input Single-Ended Input 4 10 dB dB Step 2 Differential Input Single-Ended Input 2 8 dB dB Step 3 Differential Input Single-Ended Input 0 6 dB dB 0 -6 -12 dB dB dB Speaker Mode –103 dB Headphone Mode –123 dB Speaker Mode, f = 1kHz, VIN = 200mVP-P 66.1 dB 70 dB Volume Control Minimum Gain Maximum Gain LS Second Gain Stage AV Gain HP Second Gain Stage Step 0 Step 1 Step 2 Mute CMRR Mute Attenuation Common Mode Rejection Ratio OCL Headphone Mode, f = 1kHz, VIN = 200mVP-P Differential Input Mode, VRIPPLE = 200mVP-P PSRR Power Supply Rejection Ratio OCL HP Mode, f = 217Hz OCL HP Mode, f = 1kHz LS Mode, f = 217Hz LS Mode, f = 1kHz 78.1 75.4 74 72.9 dB dB dB dB Single-Ended Input Mode, VRIPPLE = 200mVP-P PSRR Power Supply Rejection Ratio OCL HP Mode, f = 217Hz OCL HP Mode, f = 1kHz LS Mode, f = 217Hz LS Mode, f = 70.31kHz72.8 77.5 81 69 81 dB dB dB dB All Inputs ON, Single-Ended Input Mode, VRIPPLE = 200mVP-P PSRR Power Supply Rejection Ratio www.national.com OCL HP Mode, f = 217Hz OCL HP Mode, f = 1kHz LS Mode, f = 217Hz LS Mode, f = 1kHz 6 66.1 70.5 65.4 72.2 dB dB dB dB LM4949 Symbol IDD Parameter Supply Current Conditions Shutdown Supply Current VOS Output Offset Voltage POUT Output Power Limit Units (Limits) (Note 6) (Notes 7, 8) LS Mode Stereo Mono 6.8 4.9 7.3 5.3 mA (max) mA (max) OCL HP Mode Stereo Mono 5.8 4.9 6.5 5.5 mA (max) mA (max) CC HP Mode Stereo Mono 4.7 4.1 5.2 4.6 mA (max) mA (max) 0.03 1 µA (max) 6.7 8.9 20 49 mV (max) mV (max) Stereo LS + HP Mode ISD Typical Headphone Speaker 9.36 mA LS Mode, f = 1 kHz RL = 4Ω, THD+N = 10% RL = 4Ω, THD+N = 1% RL = 8Ω, THD+N = 10% RL = 8Ω, THD+N = 1% 1.24 1 0.765 0.615 W W W W OCL HP Mode, f = 1 kHz RL = 16Ω, THD+N = 10% RL = 16Ω, THD+N = 1% RL = 32Ω, THD+N = 10% RL = 32Ω, THD+N = 1% 94 76 55 45 mW mW mW mW CC HP Mode, f = 1 kHz RL = 16Ω, THD+N = 10% RL = 16Ω, THD+N = 1% RL = 32Ω, THD+N = 10% RL = 32Ω, THD+N = 1% 93 75 56 45 mW mW mW mW HP Mode, RL = 16Ω, POUT = 50mW OCL CC 0.021 0.021 % % HP Mode, RL = 32Ω, POUT = 30mW OCL CC 0.01 0.01 % % LS Mode RL = 4Ω, POUT = 400mW RL = 8Ω, POUT = 300mW 0.023 0.02 % % HP Mode, RL = 16Ω, POUT = 50mW OCL CC 0.021 0.017 % % HP Mode, RL = 32Ω, POUT = 30mW OCL CC 0.02 0.015 % % LS Mode RL = 4Ω, POUT = 400mW RL = 8Ω, POUT = 300mW 0.05 0.034 % % Differential Mode, f = 1kHz THD+N Total Harmonic Distortion + Noise Single-Ended Input Mode, f = 1kHz THD+N Total Harmonic Distortion + Noise 7 www.national.com LM4949 Electrical Characteristics VDD = 3.6V (Notes 1, 2) The following specifications apply for AV = 0dB, RL(SP) = 15µH + 8Ω + 15µH, RL(HP) = 32Ω, f = 1kHz unless otherwise specified. Limits apply for TA = 25˚C. LM4949 Electrical Characteristics VDD = 3.6V (Notes 1, 2) The following specifications apply for AV = 0dB, RL(SP) = 15µH + 8Ω + 15µH, RL(HP) = 32Ω, f = 1kHz unless otherwise specified. Limits apply for TA = 25˚C. (Continued) LM4949 Symbol Parameter Conditions Typical Limit (Note 6) (Notes 7, 8) Units (Limits) Differential Mode, A-weighted, Input Referred eN η Noise Efficiency Mono Input OCL CC LS 16.4 15.5 43 µV µV µV All Inputs ON OCL CC LS 29.8 29.2 46.6 µV µV µV Single-Ended Input, A-weighted, Input Referred Stereo Input OCL CC LS 12 11 45 µV µV µV All Inputs ON OCL CC LS 23.7 22.9 52 µV µV µV LS Mode, POUT = 400mW, RL = 8Ω 86.5 % 86 dB LS Mode, f = 1kHz, RL = 8Ω, VIN = 1VP-P Xtalk Crosstalk Differential Input Mode OCL HP Mode, f = 1kHz, RL = 32Ω, VIN = 1VP-P Differential Input Mode 68 dB 75 14 31 ms ms TON Turn on Time CC Mode OCL Mode LS Mode TOFF Turn off Time From any mode 692 ms Input Impedance Maximum Gain Minimum Gain 24.8 222.7 kΩ kΩ ZIN www.national.com 8 LM4949 Symbol Parameter Conditions Volume Control Minimum Gain Maximum Gain Typical Limit (Note 6) (Notes 7, 8) Units (Limits) –57 18 dB dB Step 0 Differential Input Single-Ended Input 6 12 dB dB Step 2 Differential Input Single-Ended Input 4 10 dB dB Step 2 Differential Input Single-Ended Input 2 8 dB dB Step 3 Differential Input Single-Ended Input 0 6 dB dB 0 –6 –12 dB dB Speaker Mode –84 dB Headphone Mode –95 dB Speaker Mode, f = 1kHz, VIN = 200mVP-P 66 dB 68.6 dB LS Second Gain Stage AV Gain HP Second Gain Stage Step 0 Step 1 Step 2 Mute CMRR Mute Attenuation Common Mode Rejection Ratio OCL Headphone Mode, f = 1kHz, VIN = 200mVP-P Differential Input Mode, VRIPPLE = 200mVP-P PSRR Power Supply Rejection Ratio OCL HP Mode, f = 217Hz OCL HP Mode, f = 1kHz LS Mode, f = 217Hz LS Mode, f = 1kHz 75 75 73 73 dB dB dB dB Single-Ended Input Mode, VRIPPLE = 200mVP-P PSRR Power Supply Rejection Ratio OCL HP Mode, f = 217Hz OCL HP Mode, f = 1kHz LS Mode, f = 217Hz LS Mode, f = 1kHz 75 75 67 71 dB dB dB dB All Inputs ON, Single-Ended Input Mode, VRIPPLE = 200mVP-P PSRR Power Supply Rejection Ratio OCL HP Mode, f = 217Hz OCL HP Mode, f = 1kHz LS Mode, f = 217Hz LS Mode, f = 1kHz 9 72 70 60 65 dB dB dB dB www.national.com LM4949 Electrical Characteristics VDD = 3.6V (Notes 1, 2) The following specifications apply for AV = 0dB, RL(SP) = 15µH + 8Ω + 15µH, RL(HP) = 32Ω, f = 1kHz unless otherwise specified. Limits apply for TA = 25˚C. (Continued) LM4949 Electrical Characteristics VDD = 5.0V (Notes 1, 2) The following specifications apply for AV = 0dB, RL(SP) = 15µH + 8Ω + 15µH, RL(HP) = 32Ω, f = 1kHz unless otherwise specified. Limits apply for TA = 25˚C. LM4949 Symbol IDD Parameter Supply Current Conditions Shutdown Supply Current VOS Output Offset Voltage POUT Output Power Limit Units (Limits) (Note 6) (Notes 7, 8) LS Mode Stereo Mono 9.9 6.6 10.9 7.2 mA (max) mA (max) OCL HP Mode Stereo Mono 6.6 5.5 7.3 6.2 mA (max) mA (max) CC HP Mode Stereo Mono 5.4 4.3 5.9 4.8 mA (max) mA (max) 0.1 1 µA (max) Headphone Speaker 10 9.6 52 50 mV (max) mV (max) LS Mode, f = 1 kHz RL = 4Ω, THD+N = 10% RL = 4Ω, THD+N = 1% RL = 8Ω, THD+N = 10% RL = 8Ω, THD+N = 1% 2.5 2.01 1.48 1.19 W W W W OCL HP Mode, f = 1 kHz RL = 16Ω, THD+N = 10% RL = 16Ω, THD+N = 1% RL = 32Ω, THD+N = 10% RL = 32Ω, THD+N = 1% 190 154 109 89 mW mW mW mW CC HP Mode, f = 1 kHz RL = 16Ω, THD+N = 10% RL = 16Ω, THD+N = 1% RL = 32Ω, THD+N = 10% RL = 32Ω, THD+N = 1% 188 153 105 88 mW mW mW mW HP Mode, RL = 16Ω, POUT = 100mW OCL CC 0.02 0.027 % % HP Mode, RL = 32Ω, POUT = 50mW OCL CC 0.02 0.022 % % LS Mode RL = 4Ω, POUT = 1W RL = 8Ω, POUT = 600mW 0.022 0.02 % % Stereo LS + HP Mode ISD Typical 13 mA Differential Input Mode, f = 1kHz THD + N Total Harmonic Distortion + Noise www.national.com 10 LM4949 Symbol Parameter Conditions Typical Limit (Note 6) (Notes 7, 8) Units (Limits) Single-Ended Input Mode, f = 1kHz THD + N Total Harmonic Distortion + Noise HP Mode, RL = 16Ω, POUT = 100mW OCL CC 0.021 0.02 % % HP Mode, RL = 32Ω, POUT = 50mW OCL CC 0.02 0.017 % % LS Mode RL = 4Ω, POUT = 1W RL = 8Ω, POUT = 600mW 0.05 0.033 % % Differential Input, A-weighted, Input Referred eN η Noise Efficiency Mono Input OCL CC LS 16.4 15.5 43 µV µV µV All Inputs ON OCL CC LS 29.8 29.2 46.6 µV µV µV Single-Ended Input, A-weighted, Input Rrferred Stereo Input OCL CC LS 12 11 45 µV µV µV All Inputs ON OCL CC LS 23.7 22.9 52 µV µV µV LS Mode, POUT = 1W, RL = 8Ω 87.4 % 105.8 dB LS Mode, f = 1kHz, RL = 8Ω, VIN = 1VP-P Xtalk Crosstalk Differential Input Mode OCL HP Mode, f = 1kHz, RL = 32Ω, VIN = 1VP-P Differential Input Mode ZIN dB 89 14 35 ms ms ms Turn on Time CC Mode OCL Mode LS Mode Turn off Time From any mode 716 ms Input Impedance Maximum Gain Minimum Gain 24.8 222.7 kΩ kΩ TON TOFF 69.6 11 www.national.com LM4949 Electrical Characteristics VDD = 5.0V (Notes 1, 2) The following specifications apply for AV = 0dB, RL(SP) = 15µH + 8Ω + 15µH, RL(HP) = 32Ω, f = 1kHz unless otherwise specified. Limits apply for TA = 25˚C. (Continued) LM4949 Electrical Characteristics VDD = 5.0V (Notes 1, 2) The following specifications apply for AV = 0dB, RL(SP) = 15µH + 8Ω + 15µH, RL(HP) = 32Ω, f = 1kHz unless otherwise specified. Limits apply for TA = 25˚C. (Continued) LM4949 Symbol Parameter Conditions Typical Limit (Note 6) (Notes 7, 8) Volume Control Minimum Gain Maximum Gain Units (Limits) –57 18 dB dB Step 0 Differential Input Single-Ended Input 6 12 dB dB Step 1 Differential Input Single-Ended Input 4 10 dB dB Step 2 Differential Input Single-Ended Input 8 2 dB dB Step 3 Differential Input Single-Ended Input 0 6 dB dB 0 –6 –12 dB dB dB LS Second Gain Stage AV Gain HP Second Gain Stage Step 0 Step 1 Step 2 Mute CMRR Mute Attenuation Common Mode Rejection Ratio Speaker Mode –102.7 dB Headphone Mode –123 dB Speaker Mode, f = 1kHz, VIN = 200mVP-P 64.4 dB OCL Headphone Mode, f = 1kHz, VIN = 200mVP-P 74.3 dB Differential Input Mode, VRIPPLE = 200mVP-P OCL HP Mode, f = 217Hz PSRR Power Supply Rejection Ratio 68.3 dB OCL HP Mode, f = 1kHz 67.9 LS Mode, f = 217Hz 73.8 dB 72 dB LS Mode, f = 1kHz dB Single-Ended Input Mode, VRIPPLE = 200mVP-P PSRR Power Supply Rejection Ratio OCL HP Mode, f = 217Hz 70.55 dB OCL HP Mode, f = 1kHz 63.05 dB LS Mode, f = 217Hz 64.6 dB LS Mode, f = 1kHz 70.3 dB All Inputs ON, Single-Ended Input Mode, VRIPPLE = 200mVP-P PSRR Power Supply Rejection Ratio www.national.com OCL HP Mode, f = 217Hz 63.1 dB OCL HP Mode, f = 1kHz 66.4 dB LS Mode, f = 217Hz 59.1 dB LS Mode, f = 1kHz 69.3 dB 12 Note 1: All voltages are measured with respect to the ground pin, unless otherwise specified. Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which guarantee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit is given, however, the typical value is a good indication of device performance. Note 3: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, θJA, and the ambient temperature TA. The maximum allowable power dissipation is PDMAX = (TJMAX – TA) / θJA or the number given in Absolute Maximum Ratings, whichever is lower. For the LM4949, see power derating currents for additional information. Note 4: Human body model, 100pF discharged through a 1.5kΩ resistor. Note 5: Machine Model, 220pF – 240pF discharged through all pins. Note 6: Typicals are measured at 25˚C and represent the parametric norm. Note 7: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level). Note 8: Datasheet min/max specification limits are guaranteed by design, test or statistical analysis. 13 www.national.com LM4949 Electrical Characteristics VDD = 5.0V (Notes 1, 2) The following specifications apply for AV = 0dB, RL(SP) = 15µH + 8Ω + 15µH, RL(HP) = 32Ω, f = 1kHz unless otherwise specified. Limits apply for TA = 25˚C. (Continued) LM4949 TABLE 1. Bump Description BUMP NAME A1 LLS- Left Channel Loudspeaker Inverting Output A2 LLS+ Left Channel Loudspeaker Non-inverting Output A3 SDA Serial Data Input A4 HPGND A5 HPR B1 VDDLS B2 ADR Address Select Bit B3 RIN- Right Channel Inverting Input B4 HPL Left Channel Headphone Output Headphone Return Bias Output www.national.com DESCRIPTION Headphone Ground Right Channel Headphone Output Speaker Power Supply B5 VOC C1 GNDLS C2 VDD Power Supply C3 RIN+ Right Channel Non-Inverting Input C4 LIN+ Left Channel Non-inverting Input C5 VDDHP Headphone Power Supply D1 VDDLS Speaker Power Supply 2 Speaker Ground D2 I CVDD I2C Power Supply D3 SCL Serial Clock Input D4 MIN+ Mono Channel Non-inverting Input D5 LIN- Left Channel Inverting Input E1 RLS- Right Channel Loudspeaker Inverting Output E2 RLS+ Right Channel Loudspeaker Non-inverting Output E3 GND Ground E4 MIN- Mono Channel Inverting Input E5 BYPASS Mid-rail Bias Bypass 14 LM4949 Typical Performance Characteristics THD+N vs Frequency Speaker Mode, Differential Input VDD = 3.6V, POUT = 400mW, RL = 4Ω THD+N vs Frequency Speaker Mode, Differential Input VDD = 3.0V, POUT = 300mW, RL = 4Ω 202001F0 202001F1 THD+N vs Frequency Speaker Mode, Differential Input VDD = 3.0V, POUT = 150mW, RL = 8Ω THD+N vs Frequency Speaker Mode, Differential Input VDD = 5.0V, POUT = 1W, RL = 4Ω 202001F2 202001F3 THD+N vs Frequency Speaker Mode, Differential Input VDD = 5.0V, POUT = 600mW, RL = 8Ω THD+N vs Frequency Speaker Mode, Differential Input VDD = 3.6V, POUT = 300mW, RL = 8Ω 202001F4 202001F5 15 www.national.com LM4949 Typical Performance Characteristics (Continued) THD+N vs Frequency Speaker Mode, Single-Ended Input VDD = 3.6V, POUT = 400mW, RL = 4Ω THD+N vs Frequency Speaker Mode, Single-Ended Input VDD = 3.0V, POUT = 300mW, RL = 4Ω 202001F6 202001F7 THD+N vs Frequency Speaker Mode, Single-Ended Input VDD = 3.0V, POUT = 150mW, RL = 8Ω THD+N vs Frequency Speaker Mode, Single-Ended Input VDD = 5.0V, POUT = 1W, RL = 4Ω 202001F8 202001F9 THD+N vs Frequency Speaker Mode, Single-Ended Input VDD = 5.0V, POUT = 600mW, RL = 8Ω THD+N vs Frequency Speaker Mode, Single-Ended Input VDD = 3.6V, POUT = 300mW, RL = 8Ω 202001G1 202001G0 www.national.com 16 (Continued) THD+N vs Frequency OCL Headphone Mode, Differential Input VDD = 3.0V, POUT = 35mW, RL = 16Ω THD+N vs Frequency OCL Headphone Mode, Differential Input VDD = 3.6V, POUT = 50mW, RL = 16Ω 202001G2 202001G3 THD+N vs Frequency OCL Headphone Mode, Differential Input VDD = 5.0V, POUT = 100mW, RL = 16Ω THD+N vs Frequency OCL Headphone Mode, Differential Input VDD = 3.0V, POUT = 20mW, RL = 32Ω 202001G4 202001G5 THD+N vs Frequency OCL Headphone Mode, Differential Input VDD = 3.6V, POUT = 30mW, RL = 32Ω THD+N vs Frequency OCL Headphone Mode, Differential Input VDD = 5.0V, POUT = 50mW, RL = 32Ω 202001G6 202001G7 17 www.national.com LM4949 Typical Performance Characteristics LM4949 Typical Performance Characteristics (Continued) THD+N vs Frequency OCL Headphone Mode, Single-Ended Input VDD = 3.6V, POUT = 50mW, RL = 16Ω THD+N vs Frequency OCL Headphone Mode, Single-Ended Input VDD = 3.0V, POUT = 35mW, RL = 16Ω 202001G8 202001G9 THD+N vs Frequency OCL Headphone Mode, Single-Ended Input VDD = 3.0V, POUT = 20mW, RL = 32Ω THD+N vs Frequency OCL Headphone Mode, Single-Ended Input VDD = 5.0V, POUT = 100mW, RL = 16Ω 202001H0 202001H1 THD+N vs Frequency OCL Headphone Mode, Single-Ended Input VDD = 5.0V, POUT = 50mW, RL = 32Ω THD+N vs Frequency OCL Headphone Mode, Single-Ended Input VDD = 3.6V, POUT = 30mW, RL = 32Ω 202001H2 www.national.com 202001H3 18 (Continued) THD+N vs Frequency CC Headphone Mode, Differential Input VDD = 3.6V, POUT = 50mW, RL = 16Ω THD+N vs Frequency CC Headphone Mode, Differential Input VDD = 3.0V, POUT = 35mW, RL = 16Ω 202001H4 202001H5 THD+N vs Frequency CC Headphone Mode, Differential Input VDD = 3.0V, POUT = 20mW, RL = 32Ω THD+N vs Frequency CC Headphone Mode, Differential Input VDD = 5.0V, POUT = 100mW, RL = 16Ω 202001H6 202001H7 THD+N vs Frequency CC Headphone Mode, Differential Input VDD = 5.0V, POUT = 50mW, RL = 32Ω THD+N vs Frequency CC Headphone Mode, Differential Input VDD = 3.6V, POUT = 30mW, RL = 32Ω 202001H8 202001H9 19 www.national.com LM4949 Typical Performance Characteristics LM4949 Typical Performance Characteristics (Continued) THD+N vs Frequency CC Headphone Mode, Single-Ended Input VDD = 3.6V, POUT = 50mW, RL = 16Ω THD+N vs Frequency CC Headphone Mode, Single-Ended Input VDD = 3.0V, POUT = 35mW, RL = 16Ω 202001I3 202001I4 THD+N vs Frequency CC Headphone Mode, Single-Ended Input VDD = 3.0V, POUT = 20mW, RL = 32Ω THD+N vs Frequency CC Headphone Mode, Single-Ended Input VDD = 5.0V, POUT = 100mW, RL = 16Ω 202001I5 202001I6 THD+N vs Frequency CC Headphone Mode, Single-Ended Input VDD = 5.0V, POUT = 50mW, RL = 32Ω THD+N vs Frequency CC Headphone Mode, Single-Ended Input VDD = 3.6V, POUT = 30mW, RL = 32Ω 202001I7 www.national.com 202001I8 20 LM4949 Typical Performance Characteristics (Continued) THD+N vs Output Power Speaker Mode, Differential Input AV = 6dB, RL = 8Ω, f = 1kHz THD+N vs Output Power Speaker Mode, Differential Input AV = 6dB, RL = 4Ω, f = 1kHz 202001D1 202001D0 THD+N vs Output Power Speaker Mode, Single-Ended Input AV = 6dB, RL = 8Ω, f = 1kHz THD+N vs Output Power Speaker Mode, Single-Ended Input AV = 6dB, RL = 4Ω, f = 1kHz 202001D2 202001D3 THD+N vs Output Power OCL Headphone Mode, Differential Input AV = 0dB, RL = 32Ω, f = 1kHz THD+N vs Output Power OCL Headphone Mode, Differential Input AV = 0dB, RL = 16Ω, f = 1kHz 202001D5 202001D4 21 www.national.com LM4949 Typical Performance Characteristics (Continued) THD+N vs Output Power OCL Headphone Mode, Single-Ended Input AV = 0dB, RL = 32Ω, f = 1kHz THD+N vs Output Power OCL Headphone Mode, Single-Ended Input AV = 0dB, RL = 16Ω, f = 1kHz 202001D6 202001D7 THD+N vs Output Power CC Headphone Mode, Differential Input AV = 0dB, RL = 32Ω, f = 1kHz THD+N vs Output Power CC Headphone Mode, Differential Input AV = 0dB, RL = 16Ω, f = 1kHz 202001D8 202001D9 THD+N vs Output Power CC Headphone Mode, Single-Ended Input AV = 0dB, RL = 32Ω, f = 1kHz THD+N vs Output Power CC Headphone Mode, Single-Ended Input AV = 0dB, RL = 16Ω, f = 1kHz 202001E1 202001E0 www.national.com 22 (Continued) PSRR vs Frequency Speaker Mode, Differential Input VDD = 3.6V, VRIPPLE = 200mVP-P, RL = 8Ω PSRR vs Frequency Speaker Mode, Differential Input VDD = 3.6V, VRIPPLE = 200mVP-P, RL = 8Ω 202001J0 202001I9 PSRR vs Frequency Speaker Mode, Single-Ended Input Stereo and Mono Inputs Active VDD = 3.6V, VRIPPLE = 200mVP-P, RL = 8Ω PSRR vs Frequency OCL Headphone Mode, Differential Input VDD = 3.6V, VRIPPLE = 200mVP-P, RL = 32Ω 202001J1 202001J2 PSRR vs Frequency OCL Headphone Mode, Single-Ended Input Stereo and Mono Inputs Active VDD = 3.6V, VRIPPLE = 200mVP-P, RL = 32Ω PSRR vs Frequency OCL Headphone Mode, Single-Ended Input VDD = 3.6V, VRIPPLE = 200mVP-P, RL = 32Ω 202001J4 202001J3 23 www.national.com LM4949 Typical Performance Characteristics LM4949 Typical Performance Characteristics (Continued) PSRR vs Frequency CC Headphone Mode, Single-Ended Input VDD = 3.6V, VRIPPLE = 200mVP-P, RL = 32Ω PSRR vs Frequency CC Headphone Mode, Differential Input VDD = 3.6V, VRIPPLE = 200mVP-P, RL = 32Ω 202001J6 202001J5 PSRR vs Frequency CC Headphone Mode, Single-Ended Input Stereo and Mono Inputs Active VDD = 3.6V, VRIPPLE = 200mVP-P, RL = 32Ω Efficiency vs Output Power Speaker Mode RL = 32Ω, f = 1kHz 202001E2 202001J7 Power Dissipation vs Output Power Speaker Mode RL = 4Ω, f = 1kHz Efficiency vs Output Power Speaker Mode RL = 8Ω, f = 1kHz 202001E3 www.national.com 20200139 24 LM4949 Typical Performance Characteristics (Continued) Power Dissipation vs Output Power OCL Headphone Mode RL = 16Ω, f = 1kHz Power Dissipation vs Output Power Speaker Mode RL = 8Ω, f = 1kHz 20200140 20200168 Power Dissipation vs Output Power CC Headphone Mode RL = 16Ω, f = 1kHz Power Dissipation vs Output Power OCL Headphone Mode RL = 32Ω, f = 1kHz 20200169 20200195 Output Power vs Supply Voltage Speaker Mode RL = 4Ω, f = 1kHz Power Dissipation vs Output Power CC Headphone Mode RL = 32Ω, f = 1kHz 202001E4 20200196 25 www.national.com LM4949 Typical Performance Characteristics (Continued) Output Power vs Supply Voltage OCL Headphone Mode RL = 16Ω, f = 1kHz Output Power vs Supply Voltage Speaker Mode RL = 8Ω, f = 1kHz 202001E6 202001E5 Output Power vs Supply Voltage CC Headphone Mode RL = 16Ω, f = 1kHz Output Power vs Supply Voltage OCL Headphone Mode RL = 32Ω, f = 1kHz 202001E7 202001E8 Output Power vs Supply Voltage CC Headphone Mode RL = 32Ω, f = 1kHz VDD CMRR vs Frequency Speaker Mode, Differential Input = 3.6V, VCM = 1VP-P, RL = 8Ω, f = 1kHz 202001E9 202001J8 www.national.com 26 VDD LM4949 Typical Performance Characteristics (Continued) CMRR vs Frequency OCL Headphone Mode = 3.6V, VCM = 1VP-P, RL = 32Ω VDD 202001J9 CMRR vs Frequency CC Headphone Mode = 3.6V, VCM = 1VP-P, RL = 32Ω 202001K3 Output Noise vs Frequency OCL Headphone Mode, Single-Ended Input Stereo and Mono Inputs Active VDD = 3.6V, RL = 32Ω Output Noise vs Frequency Speaker Mode, Single-Ended Input Stereo and Mono Inputs Active VDD = 3.6V, RL = 8Ω 202001K0 202001K1 Output Noise vs Frequency CC Headphone Mode, Single-Ended Input Stereo and Mono Inputs Active VDD = 3.6V, RL = 32Ω VDD 202001K2 Crosstalk vs Frequency Speaker Mode = 3.6V, VRIPPLE = 1VP-P, RL = 8Ω 202001I0 27 www.national.com LM4949 Typical Performance Characteristics VDD (Continued) Crosstalk vs Frequency OCL Headphone Mode = 3.6V, VRIPPLE = 1VP-P, RL = 32Ω VDD 202001I1 202001I2 Supply Current vs Supply Voltage Speaker Mode, No Load Supply Current vs Supply Voltage OCL Headphone Mode, No Load 202001B1 202001B4 Supply Current vs Supply Voltage CC Headphone Mode, No Load Supply Current vs Supply Voltage Speaker and OCL Headphone Mode, No Load 202001B8 202001B7 www.national.com Crosstalk vs Frequency CC Headphone Mode = 3.6V, VRIPPLE = 1VP-P, RL = 32Ω 28 LM4949 Typical Performance Characteristics (Continued) Supply Current vs Supply Voltage Shutdown Mode, No Load Turn-On OCL Headphone Mode 20200113 202001B9 Turn-Off OCL Headphone Mode Turn-On CC Headphone Mode 20200114 20200115 Turn-Off CC Headphone Mode 20200116 29 www.national.com LM4949 write to the I2C bus. The maximum clock frequency specified by the I2C standard is 400kHz. To avoid an address conflict with another device on the I2C bus, the LM4949 address is determined by the ADR pin, the state of ADR determines address bit A1 (Table 2). When ADR = 0, the address is 1111 1000. When ADR = 1 the device address is 1111 1010. Application Information I2C COMPATIBLE INTERFACE The LM4949 is controlled through an I2C compatible serial interface that consists of two wires; clock (SCL) and data (SDA). The clock line is uni-directional. The data line is bi-directional (open-collector) although the LM4949 does not TABLE 2. Device Address ADR A7 A6 A5 A4 X 1 1 1 1 0 1 1 1 1 1 1 1 1 1 1 BUS FORMAT A3 A2 A1 A0 1 0 X 0 1 0 0 0 0 1 0 is generated. If the LM4949 receives the address correctly, then the LM4949 pulls the data line low, generating an acknowledge bit (ACK). The I2C bus format is shown in Figure 2. The “start” signal is generated by lowering the data signal while the clock is high. The start signal alerts all devices on the bus that a device address is being written to the bus. The 8-bit device address is written to the bus next, most significant bit first. The data is latched in on the rising edge of the clock. Each address bit must be stable while the clock is high. After the last address bit is sent, the master device releases the data line, during which time, an acknowledge clock pulse Once the master device has registered the ACK bit, the 8-bit register address/data word is sent. Each data bit should be stable while the clock level is high. After the 8–bit word is sent, the LM4949 sends another ACK bit. Following the acknowledgement of the data word, the master device issues a “stop” bit, allowing SDA to go high while the clock signal is high. 20200109 FIGURE 2. I2C Bus Format 20200110 FIGURE 3. I2C Timing Diagram www.national.com 30 LM4949 Application Information (Continued) TABLE 3. I2C Control Registers REGISTER REGISTER NAME D7 D6 D5 D4 D3 D2 D1 D0 0 0 0 0 0 OCL_LGC * OCL * PWR_ON 0.1 Stereo Input Mode Control 0 0 0 1 L1_INSEL L2_INSEL 1 Speaker Output Mux Control 0 0 1 LS_XSEL LSR_MSEL LSR_SSEL LSL_MSEL LSL_SSEL 2 Headphone Output Mux Control 0 1 0 HP_XSEL HPR_MSEL HPR_SSEL HPL_MSEL HPL_SSEL 3.0 Output On/Off Control 0 1 1 0 HPR_ON HPL_ON LSR_ON LSL_ON 3.1 Reserved 0 1 1 1 RESERVED RESERVED RESERVED RESERVED 4.0 Headphone Output Stage Gain Control 1 0 0 0 HPG1 HPG0 RESERVED RESERVED 4.1 Speaker Output Stage Gain Control 1 0 0 1 LSRG1 LSRG0 LSLG1 LSLG0 5 Mono Input Gain Control 1 0 1 MG4 MG3 MG2 MG1 MG0 6 Left Input Gain Control 1 1 0 LG4 LG3 LG2 LG1 LG0 7 Right Input Gain Control 1 1 1 RG4 RG3 RG2 RG1 RG0 0.0 Shutdown Control SDB_HPSEL SDB_MUXSEL * Note: OCL_LGC = 1 and OCL = 1 at the same time is not allowed. 31 www.national.com LM4949 Application Information phone, eliminating the need for an output coupling capacitor. Removing the output coupling capacitors from the headphone signal path reduces component count, reducing system cost and board space consumption, as well as improving low frequency performance. In OCL mode, the headphone return sleeve is biased to VDD/2. When driving headphones, the voltage on the return sleeve is not an issue. However, if the headphone output is used as a line out, the VDD/2 can conflict with the GND potential that a line-in would expect on the return sleeve. When the return of the headphone jack is connected to GND, the VOC amplifier of the LM4949 detects an output short circuit condition and is disabled, preventing damage to the LM4949, and allowing the headphone return to be biased at GND. (Continued) GENERAL AMPLIFIER FUNCTION Class D Amplifier The LM4949 features a high-efficiency, filterless, Class D stereo amplifier. The LM4949 Class D amplifiers feature a filterless modulation scheme, the differential outputs of each channel switch at 300khz, from VDD to GND. When there is no input signal applied, the two outputs (_LS+ and _LS-) switch with a 50% duty cycle, with both outputs in phase. Because the outputs of the LM4949 are differential, the two signals cancel each other. This results in no net voltage across the speaker, thus no load current during the idle state, conserving power. When an input signal is applied, the duty cycle (pulse width) changes. For increasing output voltages, the duty cycle of _LS+ increases, while the duty cycle of _LS- decreases. For decreasing output voltages, the converse occurs, the duty cycle of _LS- increases while the duty cycle of _LS+ decreases. The difference between the two pulse widths yields the differential output voltage. Capacitor Coupled Headphone Mode In capacitor coupled (CC) mode, the VOC pin is disabled, and the headphone outputs are coupled to the jack through series capacitors, allowing the headphone return to be connected to GND (Figure 4). In CC mode, the LM4949 requires output coupling capacitors to block the DC component of the amplifier output, preventing DC current from flowing to the load. The output capacitor and speaker impedance form a high pass filter with a -3dB roll-off determined by: Headphone Amplifier The LM4949 headphone amplifier features three different operating modes, output capacitorless (OCL), capacitorcoupled (CC), and external amplifier mode. The OCL architecture eliminates the bulky, expensive output coupling capacitors required by traditional headphone amplifiers. The LM4949 headphone section uses three amplifiers. Two amplifiers drive the headphones while the third (VOC) is set to the internally generated bias voltage (typically VDD/2). The third amplifier is connected to the return terminal of the headphone jack. In this configuration, the signal side of the headphones are biased to VDD/2, the return is biased to VDD/2, thus there is no net DC voltage across the head- f-3dB = 1 / 2πRLCOUT Where RL is the headphone impedance, and COUT is the output coupling capacitor. Choose COUT such that f-3dB is well below the lowest frequency of interest. Setting f-3dB too high results in poor low frequency performance. Select capacitor dielectric types with low ESR to minimize signal loss due to capacitor series resistance and maximize power transfer to the load. 20200105 FIGURE 4. Capacitor Coupled Headphone Mode External Headphone Amplifier The LM4949 features the ability to drive and control a separate headphone amplifier for applications that require a True Ground headphone output (Figure 5). Configure the LM4949 into external headphone amplifier mode by setting bit D2 (OCL_LGC) in register 0.0 to 1 and bit D1 (OCL) to 0. In this mode the VOC output becomes a logic output used to drive www.national.com the shutdown input of the external amplifier. The output level of VOC is controlled by bits D1 (SDB_HPSEL) and D2 (SDB_MUXSEL) in register 0.1. SDB_MUXSEL determines the source of the VOC control signal. With SDB_MUXSEL = 0, the VOC signal comes from the internal start-up circuitry of the LM4949. This allows the external headphone amplifier to be turned on and off simultaneously with the LM4949. 32 I2C bus, bit D1. With SDB_HPSEL = 0, VOC is a logic low, with SDB_HPSEL = 1, VOC is a logic high. (Continued) When SDB_MUXSEL = 1, the VOC signal comes from the 202001C8 FIGURE 5. Driving an External Headphone Amplifier 33 www.national.com LM4949 Application Information LM4949 Application Information ended audio sources. Set bits L1_INSEL = 1 and L2_INSEL = 0 to use the RIN+ and LIN+ inputs. Set L1 _INSEL = 0 and L2_INSEL = 1 to use the RIN- and LIN- inputs. Set L1_INSEL = L2_INSEL = 1 to use both input pairs. Table 4 shows the single ended input combinations. (Continued) Single-Ended Input The left and right stereo inputs of the LM4949 can be configured for single-ended sources (Figure 6). In single-ended input mode, the LM4949 can accept up to 4 different single- 202001C9 FIGURE 6. Single-Ended Input Configuration TABLE 4. Single-Ended Stereo Input Modes INPUT MODE L1_INSEL L2_INSEL INPUT DESCRIPTION 0 0 0 Fully Differential Input Mode 1 0 1 Single-ended input. RIN- and LIN- selected 2 1 0 Single-ended input. RIN+ and LIN+ selected 3 1 1 Single-ended input. RIN+ mixed with RIN- and LIN+ mixed with LIN- www.national.com 34 the mono input on the right channel headphone. Control bits LS_XSEL (loudspeaker) and HP_XSEL (headphone) selects both stereo input channels and directs the signals to the opposite outputs, for example, LS_XSEL = 1 outputs the right channel stereo input on the left channel loudspeaker, while the left channel stereo input is output on the right channel loudspeaker. Setting __XSEL = selects both stereo inputs simultaneously, unlike the __SSEL controls which select the stereo input channels individually. (Continued) Input Mixer / Multiplexer The LM4949 includes a comprehensive mixer/multiplexer controlled through the I2C interface. The mixer/multiplexer allows any input combination to appear on any output of the LM4949. Control bits LSR_SSEL and LSL_SSEL (loudspeakers), and HPR_SSEL and HPL_SSEL (headphones) select the individual stereo input channels; for example, LSR_SSEL = 1 outputs the right channel stereo input on the right channel loudspeaker, while LSL_SSEL = 1 outputs the left channel stereo input on the left channel loudspeaker. Control bits LSR_MSEL and LSL_MSEL (loudspeaker), and HPR_MSEL and HPR_LSEL (headphones) direct the mono input to the selected output. Setting HPR_MSEL = 1 outputs Multiple input paths can be selected simultaneously. Under these conditions, the selected inputs are mixed together and output on the selected channel. Tables 5 and 6 show how the input signals are mixed together for each possible input selection combination. TABLE 5. Loudspeaker Multiplexer Control LS MODE LS_XSEL 0 LSR_MSEL/ LSL_MSEL LSR_SSEL/ LSL_SSEL LEFT CHANNEL OUTPUT RIGHT CHANNEL OUTPUT 0 0 MUTE MUTE 1 0 1 0 MONO MONO 2 0 0 1 LEFT (DIFF)/ /LIN+/LIN-/ (LIN+ - LIN-) RIGHT (DIFF)/ /RIN+/RIN-/ (RIN+ - RIN-) 3 0 1 1 MONO + LEFT (DIFF)/ /LIN+/LIN-/ (LIN+ - LIN-) MONO + RIGHT (DIFF)/ /RIN+/RIN-/ (RIN+ - RIN-) 4 1 0 1 5 1 1 1 LEFT (DIFF)/ /LIN+/LIN-/ (LIN+ LEFT (DIFF)/ /LIN+/LIN-/ (LIN+ - LIN-) + RIGHT (DIFF)/ - LIN-) + RIGHT (DIFF)/ /RIN+/RIN-/ (RIN+ - RIN-) /RIN+/RIN-/ (RIN+ - RIN-) MONO + LEFT (DIFF)/ /LIN+/LIN-/ (LIN+ - LIN-) + RIGHT (DIFF)/ /RIN+/RIN-/ (RIN+ - RIN-) MONO + LEFT (DIFF)/ /LIN+/LIN-/ (LIN+ - LIN-) + RIGHT (DIFF)/ /RIN+/RIN-/ (RIN+ - RIN-) TABLE 6. Headphone Multiplexer Control HP MODE HP_XSEL 0 HPR_MSEL/ HPL_MSEL HPR_SSEL/ LSL_SSEL LEFT CHANNEL OUTPUT RIGHT CHANNEL OUTPUT 0 0 MUTE MUTE 1 0 1 0 MONO MONO 2 0 0 1 LEFT (DIFF)/ /LIN+/LIN-/ (LIN+ - LIN-) RIGHT (DIFF)/ /RIN+/RIN-/ (RIN+ - RIN-) 3 0 1 1 MONO + LEFT (DIFF)/ /LIN+/LIN-/ (LIN+ - LIN-) MONO + RIGHT (DIFF)/ /RIN+/RIN-/ (RIN+ - RIN-) 4 1 0 1 LEFT (DIFF)/ /LIN+/LIN-/ (LIN+ - LIN-) + RIGHT (DIFF)/ /RIN+/RIN-/ (RIN+ RIN-) LEFT (DIFF)/ /LIN+/LIN-/ (LIN+ - LIN-) + RIGHT (DIFF)/ /RIN+/RIN-/ (RIN+ RIN-) 5 1 1 1 MONO + LEFT (DIFF)/ /LIN+/LIN-/ (LIN+ - LIN-) + RIGHT (DIFF)/ /RIN+/RIN-/ (RIN+ - RIN-) MONO + LEFT (DIFF)/ /LIN+/LIN-/ (LIN+ - LIN-) + RIGHT (DIFF)/ /RIN+/RIN-/ (RIN+ - RIN-) Power Supplies The LM4949 uses different supplies for each portion of the device, allowing for the optimum combination of headroom, power dissipation and noise immunity. The speaker amplifier gain stage is powered from VDD, while the output stage is powered from VDDLS. The headphone amplifiers, input amplifiers and volume control stages are powered from VDDHP. The separate power supplies allow the speakers to operate from a higher voltage for maximum headroom, while the headphones operate from a lower voltage, improving power dissipation. VDDHP may be driven by a linear regulator to further improve performance in noisy environments. The I2C portion if powered from I2CVDD, allowing the I2C portion of the LM4949 to interface with lower voltage digital controllers. 35 www.national.com LM4949 Application Information LM4949 Application Information with a range of -57dB to +18dB (Table 7). Each speaker output stage has 4 gain settings (Table 8); 0dB, 2dB, 4dB, and 6dB when either a fully differential signal or two single ended signals are applied on the _IN+ and _IN- pins; and 6dB, 8dB, 10dB and 12dB in single-ended input mode with only one signal applied. The headphone gain is not affected by the input mode. Each headphone output stage has 3 gain settings (Table 9), 0dB, -6dB, and -12dB. This allows for a maximum separation of 24dB between the speaker and headphone outputs when both are active. (Continued) Shutdown Function The LM4949 features five shutdown modes, configured through the I2C interface. Bit D0 (PWR_ON) in the Shutdown Control register shuts down/turns on the entire device. Set PWR_ON = 1 to enable the LM4949, set PWR_ON 0 to disable the device. Bits D0 – D3 in the Output On/Off Control shutdown/turn on the individual channels. HPR_ON (D3) controls the right channel headphone output, HPL_ON (D2) controls the left channel headphone output, LSR_ON (D1) controls the right channel loudspeaker output, and LRL_ON (D0) controls the left channel loudspeaker output. The PWR_ON bit takes precedence over the individual channel controls. Calculate the total gain of a given signal path as follows: AVOL + AOS = ATOTAL Where AVOL is the volume control level, AOS is the gain setting of the output stage, and ATOTAL is the total gain for the signal path. Audio Amplifier Gain Setting The each channel of the LM4949 has two separate gain stages. Each input stage features a 32 step volume control www.national.com 36 LM4949 Application Information (Continued) TABLE 7. 32 Step Volume Control Volume Step MG4/LG4/RG4 MG3/LG3/RG3 MG2/LG2/RG2 MG1/LG1/RG1 MG0/LG0/RG0 Gain (dB) 1 0 0 0 0 0 –57 2 0 0 0 0 1 –49 3 0 0 0 1 0 –42 4 0 0 0 1 1 –34.5 5 0 0 1 0 0 –30.5 6 0 0 1 0 1 –27 7 0 0 1 1 0 –24 8 0 0 1 1 1 –21 9 0 1 0 0 0 –18 10 0 1 0 0 1 –15 11 0 1 0 1 0 –13.5 12 0 1 0 1 1 –12 13 0 1 1 0 0 –10.5 14 0 1 1 0 1 –9 15 0 1 1 1 0 –7.5 16 0 1 1 1 1 –6 17 1 0 0 0 0 –4.5 18 1 0 0 0 1 –3 19 1 0 0 1 0 –1.5 20 1 0 0 1 1 0 21 1 0 1 0 0 1.5 22 1 0 1 0 1 3 23 1 0 1 1 0 4.5 24 1 0 1 1 1 6 25 1 1 0 0 0 7.5 26 1 1 0 0 1 9 27 1 1 0 1 0 10.5 28 1 1 0 1 1 12 29 1 1 1 0 0 13.5 30 1 1 1 0 1 15 31 1 1 1 1 0 16.5 32 1 1 1 1 1 18 TABLE 8. Loudspeaker Gain Setting Gain (dB) LSRG1/LSLG1 LSRG0/LSLG0 _IN+ ≠ _IN- _IN+ =_IN- 0 0 12 6 0 1 10 4 1 0 8 2 1 1 6 0 TABLE 9. Headphone Gain Setting HPG1 HPG0 0 0 0 0 1 –6 1 0 –12 37 Gain (dB) www.national.com LM4949 Application Information tors as close to the device as possible. Typical applications employ a voltage regulator with 10µF and 0.1µF bypass capacitors that increase supply stability. These capacitors do not eliminate the need for bypassing of the LM4949 supply pins. A 1µF ceramic capacitor placed close to each supply pin is recommended. (Continued) Differential Audio Amplifier Configuration As logic supply voltages continue to shrink, system designers increasingly turn to differential signal handling to preserve signal to noise ratio with decreasing voltage swing. The LM4949 can be configured as a fully differential amplifier, amplifying the difference between the two inputs. The advantage of the differential architecture is any signal component that is common to both inputs is rejected, improving common-mode rejection (CMRR) and increasing the SNR of the amplifier by 6dB over a single-ended architecture. The improved CMRR and SNR of a differential amplifier reduce sensitivity to ground offset related noise injection, especially important in noisy applications such as cellular phones. Driving the LM4949 differentially also allows the inputs to be DC coupled, eliminating two external capacitors per channel. Set bits L1_INSEL and L2_INSEL = 0 for differential input mode. The left and right stereo inputs have selectable differential or single-ended input modes, while the mono input is always differential. Bypass Capacitor Selection The LM4949 generates a VDD/2 common-mode bias voltage internally. The BYPASS capacitor, CB, improves PSRR and THD+N by reducing noise at the BYPASS node. Use a 1µF capacitor, placed as close to the device as possible for CB. Audio Amplifier Input Capacitor Selection Input capacitors, CIN, in conjunction with the input impedance of the LM4949 forms a high pass filter that removes the DC bias from an incoming signal. The AC-coupling capacitor allows the amplifier to bias the signal to an optimal DC level. Assuming zero source impedance, the -3dB point of the high pass filter is given by: f-3dB = 1 / 2πRINCIN Single-Ended Audio Amplifier Configuration In single-ended input mode, the audio sources must be capacitively coupled to the LM4949. With LIN+ ≠ LIN- and RIN+ ≠ RIN-, the loud speaker gain is 6dB more than in differential input mode, or when LIN+ = LIN- and RIN+ = RIN-. The headphone gain does not change. The mono input channel is not affected by L1_INSEL and L2_INSEL, and is always configured as a differential input. Choose CIN such that f-3dB is well below the lowest frequency of interest. Setting f-3dB too high affects the lowfrequency response of the amplifier. Use capacitors with low voltage coefficient dielectrics, such as tantalum or aluminum electrolytic. Capacitors with high-voltage coefficients, such as ceramics, may result in increased distortion at low frequencies. Other factors to consider when designing the input filter include the constraints of the overall system. Although high fidelity audio requires a flat frequency response between 20Hz and 20kHz, portable devices such as cell phones may only concentrate on the frequency range of the spoken human voice (typically 300Hz to 4kHz). In addition, the physical size of the speakers used in such portable devices limits the low frequency response; in this case, frequencies below 150Hz may be filtered out. Power Dissipation and Efficiency The major benefit of Class D amplifiers is increased efficiency versus Class AB. The efficiency of the LM4949 speaker amplifiers is attributed to the output transistors’ region of operation. The Class D output stage acts as current steering switches, consuming negligible amounts of power compared to their Class AB counterparts. Most of the power loss associated with the output stage is due to the IR loss of the MOSFET on-resistance, along with the switching losses due to gate charge. The maximum power dissipation per headphone channel in Capacitor-Coupled mode is given by: PCB LAYOUT GUIDELINES Minimize trace impedance of the power, ground and all output traces for optimum performance. Voltage loss due to trace resistance between the LM4949 and the load results in decreased output power and efficiency. Trace resistance between the power supply and GND of the LM4949 has the same effect as a poorly regulated supply, increased ripple and reduced peak output power. Use wide traces for powersupply inputs and amplifier outputs to minimize losses due to trace resistance, as well as route heat away from the device. Proper grounding improves audio performance, minimizes crosstalk between channels and prevents switching noise from interfering with the audio signal. Use of power and ground planes is recommended. Place all digital components and digital signal traces as far as possible from analog components and traces. Do not run digital and analog traces in parallel on the same PCB layer. PDMAX = VDD2 / 2π2RL In OCL mode, the maximum power dissipation per headphone channel increases due to the use of a third amplifier as a buffer. The power dissipation is given by: PDMAX = VDD2 / π2RL PROPER SELECTION OF EXTERNAL COMPONENTS Audio Amplifier Power Supply Bypassing / Filtering Proper power supply bypassing is critical for low noise performance and high PSRR. Place the supply bypass capaci- www.national.com 38 LM4949 Revision History Rev Date Description 1.0 09/06/06 Initial release. 1.1 09/27/06 Fixed some of the Typical Performance Curves. 39 www.national.com LM4949 Stereo Class D Audio Subsystem with OCL Headphone Amplifier Physical Dimensions inches (millimeters) unless otherwise noted micro SMD Package Order Number LM4949TL NS Package Number TLA25JJA National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. For the most current product information visit us at www.national.com. LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. 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