2.5 Watt Fully Differential Audio Power Amplifier

LM4927 2.5 Watt Fully Differential Audio Power Amplifier With Shutdown April 2006 LM4927 2.5 Watt Fully Differential Audio Power Amplifier With Shutdown General Description The LM4927 is a fully differential audio power amplifier primarily designed for demanding applications in mobile phones and other portable communication device applications. It is capable of delivering 2.5 watts of continuous average power to a 4Ω load with less than 10% distortion (THD+N) from a 5VDC power supply. Boomer audio power amplifiers were designed specifically to provide high quality output power with a minimal amount of external components. The LM4927 does not require output coupling capacitors or bootstrap capacitors, and therefore is ideally suited for mobile phone and other low voltage applications where minimal power consumption is a primary requirement. The LM4927 features a low-power consumption shutdown mode. To facilitate this, Shutdown may be enabled by logic low. Additionally, the LM4927 features an internal thermal shutdown protection mechanism. The LM4927 contains advanced pop & click circuitry which eliminates noises which would otherwise occur during turn-on and turn-off transitions. Key Specifications j Improved PSRR at 217Hz j Power Output at 5.0V @ 10% THD (4Ω) j Power Output at 3.3V @ 1% THD j Shutdown Current 85dB (typ) 2.5W (typ) 550mW (typ) 0.1µA (typ) Features Fully differential amplification Available in space-saving micro-array LLP package Ultra low current shutdown mode Can drive capacitive loads up to 100pF Improved pop & click circuitry eliminates noises during turn-on and turn-off transitions n 2.4 - 5.5V operation n No output coupling capacitors, snubber networks or bootstrap capacitors required n n n n n Applications n Mobile phones n PDAs n Portable electronic devices Typical Application 20152529 FIGURE 1. Typical Audio Amplifier Application Circuit Boomer ® is a registered trademark of National Semiconductor Corporation. © 2006 National Semiconductor Corporation DS201525 www.national.com LM4927 Connection Diagrams 8 Pin LLP Package 20152563 Top View Order Number LM4927SD See NS Package Number SDA08A 8 Pin LLP Marking 20152565 Top View Z = Assembly Plant XY = 2 Digit Date Code TT = Die Traceability L4927 = LM4927SD www.national.com 2 LM4927 Absolute Maximum Ratings (Note 2) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage Storage Temperature Input Voltage Power Dissipation (Note 3) ESD Susceptibility (Note 4) ESD Susceptibility (Note 5) Junction Temperature 6.0V −65˚C to +150˚C −0.3V to VDD +0.3V Internally Limited 2000V 200V 150˚C Thermal Resistance θJA (SD) Soldering Information See AN-1187 63˚C/W Operating Ratings Temperature Range TMIN ≤ TA ≤ TMAX Supply Voltage −40˚C ≤ TA ≤ 85˚C 2.4V ≤ VDD ≤ 5.5V Electrical Characteristics VDD = 5V (Notes 1, 2) The following specifications apply for VDD = 5V, AV = 1, and 8Ω load unless otherwise specified. Limits apply for TA = 25˚C. LM4927 Symbol IDD ISD Parameter Quiescent Power Supply Current Shutdown Current Conditions VIN = 0V, no load VIN = 0V, RL = 8Ω VSHUTDOWN = GND THD = 1% (max); f = 1 kHz RL = 4Ω RL = 8Ω THD = 10% (max); f = 1 kHz RL = 4Ω RL = 8Ω Po = 1 Wrms; f = 1kHz Vripple = 200mV sine p-p PSRR CMRR VOS VSDIH VSDIL SNR RF AV TWU Power Supply Rejection Ratio Common-Mode Rejection Ratio Output Offset Shutdown Voltage Input High Shutdown Voltage Input Low Signal-to-noise ratio Internal Feedback Resistance Gain Wake-up time from Shutdown PO = 1W, f = 1kHz Ri = 40kΩ Ri = 40kΩ Cbypass = 1µF 110 40 0 14 37 47 –0.68 1.4 f = 217Hz (Note 8) f = 1kHz (Note 8) f = 217Hz, VCM = 200mVpp VIN = 0V 90 85 60 4 1.4 0.4 71 dB (min) dB mV V (min) V (max) dB kΩ (min) kΩ (max) dB (min) dB (max) ms Typical (Note 6) 2.2 2.2 0.1 2.1 1.30 2.5 1.6 0.03 Limit (Note 7) 4.5 4.5 1 Units (Limits) mA (max) µA (max) Po Output Power 1.20 W (min) W % THD+N Total Harmonic Distortion+Noise Electrical Characteristics VDD = 3V (Notes 1, 2) The following specifications apply for VDD = 3V, AV = 1, and 8Ω load unless otherwise specified. Limits apply for TA = 25˚C. LM4927 Symbol IDD ISD Parameter Quiescent Power Supply Current Shutdown Current Conditions VIN = 0V, no load VIN = 0V, RL = 8Ω VSHUTDOWN = GND Typical (Note 6) 2 2 0.1 Limit (Note 7) 4.3 4.3 1 Units (Limits) mA (max) µA (max) 3 www.national.com LM4927 Electrical Characteristics VDD = 3V (Notes 1, 2) The following specifications apply for VDD = 3V, AV = 1, and 8Ω load unless otherwise specified. Limits apply for TA = 25˚C. (Continued) LM4927 Symbol Parameter Conditions THD = 1% (max); f = 1 kHz RL = 4Ω RL = 8Ω THD = 10% (max); f = 1 kHz RL = 4Ω RL = 8Ω Po = 0.25Wrms; f = 1kHz Vripple = 200mV sine p-p PSRR CMRR VOS VSDIH VSDIL TWU Power Supply Rejection Ratio Common-Mode Rejection Ratio Output Offset Shutdown Voltage Input High Shutdown Voltage Input Low Wake-up time from Shutdown Cbypass 8 f = 217Hz (Note 8) f = 1kHz (Note 8) f = 217Hz, VCM = 200mVpp VIN = 0V 85 80 60 4 1.4 0.4 dB dB mV (max) V (min) V (max) ms Typical (Note 6) 0.650 0.450 0.800 0.550 0.04 Limit (Note 7) Units (Limits) Po Output Power W W % THD+N Total Harmonic Distortion+Noise 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 LM4927, see power derating curve 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: 10Ω terminated input. Note 9: When driving 4Ω loads from a 5V power supply, the LM4927LD must be mounted to a circuit board with the exposed-DAP area soldered down to a 1in2 plane of 1oz, copper. Note 10: Data taken with BW = 80kHz and AV = 1/1 except where specified. External Components Description (Figure 1) Components 1. 2. 3. 4. CS CB Ri Rf Functional Description Supply bypass capacitor which provides power supply filtering. Refer to the Power Supply Bypassing section for information concerning proper placement and selection of the supply bypass capacitor. Bypass pin capacitor which provides half-supply filtering. Refer to the section, Proper Selection of External Components, for information concerning proper placement and selection of CB. Inverting input resistance which sets the closed-loop gain in conjunction with Rf. Internal feedback resistance which sets the closed-loop gain in conjunction with Ri. www.national.com 4 LM4927 Typical Performance Characteristics THD+N vs Frequency VDD = 2.6V, RL = 8Ω, PO = 150mW (Note 10) THD+N vs Frequency VDD = 2.6V, RL = 4Ω, PO = 150mW 20152534 20152533 THD+N vs Frequency VDD = 5V, RL = 8Ω, PO = 1W THD+N vs Frequency VDD = 5V, RL = 4Ω, PO = 1W 20152538 20152537 THD+N vs Frequency VDD = 3V, RL = 8Ω, PO = 275mW THD+N vs Frequency VDD = 3V, RL = 4Ω, PO = 225mW 20152536 20152535 5 www.national.com LM4927 Typical Performance Characteristics THD+N vs Output Power VDD = 2.6V, RL = 8Ω (Note 10) (Continued) THD+N vs Output Power VDD = 2.6V, RL = 4Ω 20152540 20152539 THD+N vs Output Power VDD = 5V, RL = 8Ω THD+N vs Output Power VDD = 5V, RL = 4Ω 20152544 20152543 THD+N vs Output Power VDD = 3V, RL = 8Ω THD+N vs Output Power VDD = 3V, RL = 4Ω 20152542 20152541 www.national.com 6 LM4927 Typical Performance Characteristics PSRR vs Frequency VDD = 5V, RL = 8Ω Inputs terminated to GND, BW = 500kHz (Note 10) (Continued) PSRR vs Frequency VDD = 3V, RL = 8Ω Inputs terminated to GND, BW = 500kHz 20152532 20152531 Output Power vs Supply Voltage RL = 8Ω Output Power vs Supply Voltage RL = 4Ω 20152555 20152554 CMRR vs Frequency VDD = 5V, RL = 8Ω CMRR vs Frequency VDD = 3V, RL = 8Ω 20152550 20152549 7 www.national.com LM4927 Typical Performance Characteristics PSRR vs Common Mode Voltage VDD = 3V, RL = 8Ω, f = 217Hz (Note 10) (Continued) PSRR vs Common Mode Voltage VDD = 5V, RL = 8Ω, f = 217Hz 20152560 20152561 Power Dissipation vs Output Power VDD = 2.6V, RL = 8Ω and 4Ω Power Dissipation vs Output Power VDD = 5V, RL = 8Ω 20152557 20152562 Power Dissipation vs Output Power VDD = 3V, RL = 8Ω Power Derating Curve 20152558 20152556 www.national.com 8 LM4927 Typical Performance Characteristics Noise Floor VDD = 5V (Note 10) (Continued) Noise Floor VDD = 3V 20152552 20152551 Clipping Voltage vs Supply Voltage Output Power vs Load Resistance 20152548 20152553 9 www.national.com LM4927 Application Information DIFFERENTIAL AMPLIFIER EXPLANATION The LM4927 is a fully differential audio amplifier that features differential input and output stages. Internally this is accomplished by two circuits: a differential amplifier and a common mode feedback amplifier that adjusts the output voltages so that the average