LM4954TLBD

LM4954 www.ti.com SNAS292B – JUNE 2005 – REVISED APRIL 2013 LM4954 Boomer™ Audio Power Amplifier Series High Voltage 3 Watt Audio Power Amplifier Check for Samples: LM4954 FEATURES DESCRIPTION • The LM4954 is an audio power amplifier primarily designed for demanding applications in mobile phones and other portable communication device applications. It is capable of delivering 2.4 Watts of continuous average power to an 8Ω BTL load with less than 1% THD+N from a 7VDC power supply. 1 23 • • • • • • • No Output Coupling Capacitors, Snubber Networks or Bootstrap Capacitors Required Unity Gain Stable Externally Configurable Gain Ultra Low Current Active Low Shutdown Mode BTL Output can Drive Capacitive Loads Up to 100pF “Click and Pop” Suppression Circuitry 2.7V - 9.0V Operation Available in Space-Saving DSBGA Package APPLICATIONS • • Mobile Phones PDAs KEY SPECIFICATIONS • • • • • Wide Power Supply Voltage Range, 2.7 ≤ VDD ≤ 9V Output Power: VDD = 7V, 1% THD+N, 2.4W (Typ) Quiescent Power Supply Current, 3mA (Typ) PSRR: VDD = 5V and 3V at 217Hz, 80dB (Typ) Shutdown Power Supply Current, 0.01µA (Typ) Boomer audio power amplifiers are designed specifically to provide high quality output power with a minimal number of external components. The LM4954 does not require output coupling capacitors or bootstrap capacitors, and therefore is ideally suited for lower-power portable applications where minimal space and power consumption are primary requirements. The LM4954 features a low-power consumption global shutdown mode which is achieved by driving the shutdown pin with logic low. Additionally, the LM4954 features an internal thermal shutdown protection mechanism. The LM4954 contains advanced pop & click circuitry which eliminates noises that would otherwise occur during turn-on and turn-off transitions. The LM4954 is unity-gain stable and can be configured by external gain-setting resistors. 1 2 3 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. Boomer is a trademark of Texas Instruments. All other trademarks are the property of their respective owners. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2005–2013, Texas Instruments Incorporated LM4954 SNAS292B – JUNE 2005 – REVISED APRIL 2013 www.ti.com Typical Application Figure 1. Typical Audio Amplifier Application Circuit Connection Diagram Figure 2. 9 Bump DSBGA Top View See Package Number YZR0009 These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. 2 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4954 LM4954 www.ti.com SNAS292B – JUNE 2005 – REVISED APRIL 2013 Absolute Maximum Ratings (1) (2) (3) Supply Voltage (1) 9.5V −65°C to +150°C Storage Temperature −0.3V to VDD +0.3V Input Voltage Power Dissipation (4) Internally Limited (5) 2000V ESD Susceptibility ESD Susceptibility (6) 200V Junction Temperature 150°C Thermal Resistance θJA (DSBGA) (7) 180°C/W Soldering Information See AN-112 (SNAA002) “DSBGA Wafers Level Chip Scale Package.” (1) (2) (3) (4) (5) (6) (7) All voltages are measured with respect to the ground pin, unless otherwise specified. 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 ensure specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which ensure specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not ensured for parameters where no limit is given, however, the typical value is a good indication of device performance. If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/Distributors for availability and specifications. 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 LM4954, see power derating curves for additional information. Human body model, 100pF discharged through a 1.5kΩ resistor. Machine Model, 220pF – 240pF discharged through all pins. All bumps have the same thermal resistance and contribute equally when used to lower thermal resistance. The θJA given in the Absolute Maximum Ratings section under Thermal Resistance is for the ITL package without any heat spreading planes on the PCB. Operating Ratings (1) (2) Temperature Range TMIN ≤ TA ≤ TMAX (1) (2) −40°C ≤ TA ≤ 85°C 2.7V ≤ VDD ≤ 9V Supply Voltage All voltages are measured with respect to the ground pin, unless otherwise specified. 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 ensure specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which ensure specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not ensured for parameters where no limit is given, however, the typical value is a good indication of device performance. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4954 3 LM4954 SNAS292B – JUNE 2005 – REVISED APRIL 2013 www.ti.com Electrical Characteristics VDD = 7V (1) (2) The following specifications apply for VDD = 7V, AV-BTL = 6dB, and RL = 8Ω unless otherwise specified. Limits apply for TA = 25°C. Symbol Parameter Conditions IDD Quiescent Power Supply Current VIN = 0V, RL = 8Ω BTL ISD Shutdown Current VSD = GND (6) VOS Output Offset Voltage Po Output Power (7) THD+N PSRR Total Harmonic Distortion + Noise Power Supply Rejection Ratio VSDIH Shutdown High Input Voltage VSDIL Shutdown Low Input Voltage TWU Wake-up Time ∈OUT RPD (1) (2) (3) (4) (5) (6) (7) 4 Output Noise LM4954 Typical (3) Limit (4) (5) Units (Limits) mA (max) 3 5 0.01 1 µA (max) 10 25 mV (max) THD+N = 1% (max); f = 1kHz 2.4 2.2 W (min) THD+N = 10% (max); f = 1kHz 3.0 W PO = 1Wrms; f = 1kHz AV-BTL = 6dB 0.1 % PO = 1Wrms; f = 1kHz AV-BTL = 26dB 0.4 % VRipple = 200mVsine p-p, CB = 2.2µF, Input terminated with 10Ω to GND fRipple = 217Hz, Input Referred 71 54 dB (min) VRipple = 200mVsine p-p, CB = 2.2µF, Input terminated with 10Ω to ground fRipple = 1kHz, Input Referred 71 55 dB (min) 1.2 V (min) 0.4 V (max) CB = 2.2µF 130 ms A-Wtg, AV-BTL = 6dB Input terminated with 10Ω to GND, Output Referred 20 µVRMS A-Wtg, AV-BTL = 26dB Input terminated with 10Ω to GND, Output Referred 100 µVRMS 75 kΩ Pull Down Resistor on Shutdown All voltages are measured with respect to the ground pin, unless otherwise specified. 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 ensure specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which ensure specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not ensured for parameters where no limit is given, however, the typical value is a good indication of device performance. Typical specifications are specified at 25°C and represent the parametric norm. Tested limits are specified to Texas Instruments' AOQL (Average Outgoing Quality Level). Datasheet min/max specification limits are specified by design, test, or statistical analysis. Shutdown current is measured in a normal room environment. Exposure to direct sunlight in the TL package will increase ISD by a minimum of 2μA. The demo board shown has 1.1in2 (710mm2) heat spreading planes on the two internal layers and the bottom layer. The bottom internal layer is electrically VDD while the top internal and bottom layers are electrically GND. Thermal performance for the demo board is found on the Power Derating graph in the Typical Performance Characteristics section. 7V operation requires heat spreading planes for the thermal stability. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4954 LM4954 www.ti.com SNAS292B – JUNE 2005 – REVISED APRIL 2013 Electrical Characteristics VDD = 5V (1) (2) The following specifications apply for VDD = 5V, AV-BTL = 6dB, and RL = 8Ω unless otherwise specified. Limits apply for TA = 25°C. Symbol Parameter Conditions LM4954 Typical (3) Limit (4) (5) Units (Limits) mA (max) IDD Quiescent Power Supply Current VIN = 0V, RL = 8Ω BTL 2.7 5 ISD Shutdown Current VSD = GND (6) 0.01 1 µA (max) VOS Output Offset Voltage 8 25 mV (max) Po Output Power THD+N = 1% (max); f = 1kHz 1.2 1.1 W (min) THD+N Total Harmonic Distortion + Noise PO = 600mWrms; f = 1kHz 0.1 Vripple = 200mVsine p-p, CB = 2.2µF, Input terminated with 10Ω to GND fRipple = 217Hz, Input Referred 80 Vripple = 200mVsine p-p, CB = 2.2µF, Input terminated with 10Ω to GND fRipple = 1kHz, Input Referred 80 PSRR Power Supply Rejection Ratio % 63 dB (min) dB VSDIH Shutdown High Input Voltage 1.2 V (min) VSDIL Shutdown Low Input Voltage 0.4 V (max) TWU Wake-up Time CB = 2.2µF 130 ms ∈OUT Output Noise A-Wtg, Input terminated with 10Ω to GND, Output referred 20 µVRMS RPD Pul Down Resistor on Shutdown 75 kΩ (1) (2) (3) (4) (5) (6) All voltages are measured with respect to the ground pin, unless otherwise specified. 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 ensure specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which ensure specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not ensured for parameters where no limit is given, however, the typical value is a good indication of device performance. Typical specifications are specified at 25°C and represent the parametric norm. Tested limits are specified to Texas Instruments' AOQL (Average Outgoing Quality Level). Datasheet min/max specification limits are specified by design, test, or statistical analysis. Shutdown current is measured in a normal room environment. Exposure to direct sunlight in the TL package will increase ISD by a minimum of 2μA. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4954 5 LM4954 SNAS292B – JUNE 2005 – REVISED APRIL 2013 www.ti.com Electrical Characteristics VDD = 3V (1) (2) The following specifications apply for VDD = 3V, AV-BTL = 6dB, and RL = 8Ω unless otherwise specified. Limits apply for TA = 25°C. Symbol Parameter LM4954 Conditions Typical (3) Limit (4) (5) Units (Limits) mA (max) IDD Quiescent Power Supply Current VIN = 0V, RL = 8Ω BTL 2.5 5 ISD Shutdown Current VSD = GND (6) 0.01 1 µA (max) VOS Output Offset Voltage 5 25 mV (max) Po Output Power THD+N = 1% (max); f = 1kHz 380 360 mW (min) THD+N Total Harmonic Distortion + Noise Po = 100mWrms; f = 1kHz 0.18 PSRR Power Supply Rejection Ratio Vripple = 200mVsine p-p, CB = 2.2µF, Input teiminated with 10Ω to GND, fRipple = 217Hz, Input referred 80 Vripple = 200mVsine p-p, CB = 2.2µF, Input teiminated with 10Ω to GND, fRipple = 1kHz, Input referred 80 % 63 dB (min) dB VSDIH Shutdown High Input Voltage 1.2 V (min) VSDIL Shutdown Low Input Voltage 0.4 V (max) TWU Wake-Up Time CB = 2.2μF 130 ms ∈OUT Output Noise A-Wtg, Input terminated with 10Ω to GND, Output referred 20 μVRMS RPD Pull Down Resistor on Shutdown 75 kΩ (1) (2) (3) (4) (5) (6) All voltages are measured with respect to the ground pin, unless otherwise specified. 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 ensure specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which ensure specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not ensured for parameters where no limit is given, however, the typical value is a good indication of device performance. Typical specifications are specified at 25°C and represent the parametric norm. Tested limits are specified to Texas Instruments' AOQL (Average Outgoing Quality Level). Datasheet min/max specification limits are specified by design, test, or statistical analysis. Shutdown current is measured in a normal room environment. Exposure to direct sunlight in the TL package will increase ISD by a minimum of 2μA. External Components Description (See Figure 1) Components 6 Functional Description 1. Ri Inverting input resistance which sets the closed-loop gain in conjunction with Rf. This resistor also forms a high pass filter with Ci at fC = 1/(2π RiCi). 2. Ci Input coupling capacitor which blocks the DC voltage at the amplifiers input terminals. Also creates a highpass filter with Ri at fc = 1/(2π RiCi). Refer to the section, PROPER SELECTION OF EXTERNAL COMPONENTS, for an explanation of how to determine the value of Ci. 3. Rf Feedback resistance which sets the closed-loop gain in conjunction with Ri. AVD = 2 * (Rf/Ri). 4. CS 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. 5. CB 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. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4954 LM4954 www.ti.com SNAS292B – JUNE 2005 – REVISED APRIL 2013 Typical Performance Characteristics THD+N vs Output Power VDD = 7V, RL = 8Ω, AV = 6dB, f = 1kHz, 80kHz BW THD+N vs Frequency VDD = 7V, RL = 8Ω, AV = 6dB, POUT = 600mW, 80kHz BW Figure 3. Figure 4. THD+N vs Output Power VDD = 7V, RL = 8Ω, AV = 26dB, f = 1kHz, 80kHz BW THD+N vs Frequency VDD = 7V, RL = 8Ω, AV = 26dB, POUT = 600mW, 80kHz BW Figure 5. Figure 6. THD+N vs Output Power VDD = 5V, RL = 4Ω, AV = 6dB, f = 1kHz, 80kHz BW THD+N vs Frequency VDD = 5V, RL = 4Ω, AV = 6dB, POUT = 100mW, 80kHz BW Figure 7. Figure 8. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4954 7 LM4954 SNAS292B – JUNE 2005 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (continued) 8 THD+N vs Output Power VDD = 5V, RL = 8Ω, AV = 6dB, f = 1kHz, 80kHz BW THD+N vs Frequency VDD = 5V, RL = 8Ω, AV = 6dB, POUT = 100mW, 80kHz BW Figure 9. Figure 10. THD+N vs Output Power VDD = 3V, RL = 4Ω, AV = 6dB, f = 1kHz, 80kHz BW THD+N vs Frequency VDD = 3V, RL = 4Ω, AV = 6dB, POUT = 100mW, 80kHz BW Figure 11. Figure 12. THD+N vs Output Power VDD = 3V, RL = 8Ω, AV = 6dB, f = 1kHz, 80kHz BW THD+N vs Frequency VDD = 3V, RL = 8Ω, AV = 6dB, POUT = 100mW, 80kHz BW Figure 13. Figure 14. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4954 LM4954 www.ti.com SNAS292B – JUNE 2005 – REVISED APRIL 2013 Typical Performance Characteristics (continued) THD+N vs Differential Gain VDD = 7V, RL = 8Ω, POUT = 600mW, 80kHz BW PSRR vs Frequency VDD = 7V, VRIPPLE = 200mVP-P Input Terminated, 80kHz BW Figure 15. Figure 16. PSRR vs Frequency VDD = 5V, VRIPPLE = 200mVP-P Input Terminated, 80kHz BW PSRR vs Frequency VDD = 3V, VRIPPLE = 200mVP-P Input Terminated, 80kHz BW Figure 17. Figure 18. Output Power vs Supply Voltage RL = 4Ω, AV = 6dB, 80kHz BW Output Power vs Supply Voltage RL = 8Ω, AV = 6dB, 80kHz BW Figure 19. Figure 20. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4954 9 LM4954 SNAS292B – JUNE 2005 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (continued) (1) (2) 10 Power Dissipation vs Output Power VDD = 7V, AV = 6dB, THD+N ≤ 1%, 80kHz BW Power Dissipation vs Output Power VDD = 5V, AV = 6dB, THD+N ≤ 1%, 80kHz BW Figure 21. Figure 22. Power Dissipation vs Output Power VDD = 3V, AV = 6dB, THD+N ≤ 1%, 80kHz BW Power Derating – 9 bump DSBGA PDMAX = 1.26W, VDD = 7V, RL = 8Ω (1) (2) Figure 23. Figure 24. All bumps have the same thermal resistance and contribute equally when used to lower thermal resistance. The θJA given in the Absolute Maximum Ratings section under Thermal Resistance is for the ITL package without any heat spreading planes on the PCB. The demo board shown has 1.1in2 (710mm2) heat spreading planes on the two internal layers and the bottom layer. The bottom internal layer is electrically VDD while the top internal and bottom layers are electrically GND. Thermal performance for the demo board is found on the Power Derating graph in the Typical Performance Characteristics section. 7V operation requires heat spreading planes for the thermal stability. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4954 LM4954 www.ti.com SNAS292B – JUNE 2005 – REVISED APRIL 2013 Typical Performance Characteristics (continued) Shutdown Threshold vs Supply Voltage RL = 8Ω, AV = 6dB, 80kHz BW Supply Current vs Supply Voltage RL = 8Ω Figure 25. Figure 26. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4954 11 LM4954 SNAS292B – JUNE 2005 – REVISED APRIL 2013 www.ti.com APPLICATION INFORMATION BRIDGE CONFIGURATION EXPLANATION As shown in Figure 1, the LM4954 has two operational amplifiers internally, allowing for a few different amplifier configurations. The first amplifier's gain is externally configurable, while the second amplifier is internally fixed in a unity-gain, inverting configuration. The closed-loop gain of the first amplifier is set by selecting the ratio of Rf to Ri while the second amplifier's gain is fixed by the two internal 20kΩ resistors. Figure 1 shows that the output of amplifier one serves as the input to amplifier two which results in both amplifiers producing signals identical in magnitude, but out of phase by 180°. Consequently, the differential gain for the IC is AVD = 2 *(Rf/Ri) (1) By driving the load differentially through outputs Vo1 and Vo2, an amplifier configuration commonly referred to as “bridged mode” is established. Bridged mode operation is different from the classical single-ended amplifier configuration where one side of the load is connected to ground. A bridge amplifier design has a few distinct advantages over the single-ended configuration, as it provides differential drive to the load, thus doubling output swing for a specified supply voltage. Four times the output power is possible as compared to a single-ended amplifier under the same conditions. This increase in attainable output power assumes that the amplifier is not current limited or clipped. In order to choose an amplifier's closedloop gain without causing excessive clipping, please refer to the AUDIO POWER AMPLIFIER DESIGN section. A bridge configuration, such as the one used in LM4954, also creates a second advantage over single-ended amplifiers. Since the differential outputs, Vo1 and Vo2, are biased at half-supply, no net DC voltage exists across the load. This eliminates the need for an output coupling capacitor which is required in a single supply, singleended amplifier configuration. Without an output coupling capacitor, the half-supply bias across the load would result in both increased internal IC power dissipation and also possible loudspeaker damage. POWER DISSIPATION Power dissipation is a major concern when designing a successful amplifier, whether the amplifier is bridged or single-ended. A direct consequence of the increased power delivered to the load by a bridge amplifier is an increase in internal power dissipation. Since the LM4954 has two operational amplifiers in one package, the maximum internal power dissipation is four times that of a single-ended amplifier. The maximum power dissipation for a given application can be derived from the power dissipation graphs or from Equation 2. PDMAX = 4*(VDD)2/(2π2RL) (2) It is critical that the maximum junction temperature (TJMAX) of 150°C is not exceeded. TJMAX can be determined from the power derating curves by using PDMAX and the PC board foil area. By adding additional copper foil, the thermal resistance of the application can be reduced from the free air value, resulting in higher PDMAX. Additional copper foil can be added to any of the leads connected to the LM4954. It is especially effective when connected to VDD, GND, and the output pins. Refer to the application information on the LM4954 reference design board for an example of good heat sinking. If TJMAX still exceeds 150°C, then additional changes must be made. These changes can include reduced supply voltage, higher load impedance, or reduced ambient temperature. Internal power dissipation is a function of output power. Refer to the Typical Performance Characteristics curves for power dissipation information for different output powers and output loading. POWER SUPPLY BYPASSING As with any amplifier, proper supply bypassing is critical for low noise performance and high power supply rejection. The capacitor location on both the bypass and power supply pins should be as close to the device as possible. Typical applications employ a 5V regulator with 10µF tantalum or electrolytic capacitor and a ceramic bypass capacitor which aid in supply stability. This does not eliminate the need for bypassing the supply nodes of the LM4954. The selection of a bypass capacitor, especially CB, is dependent upon PSRR requirements, click and pop performance (as explained in the section, PROPER SELECTION OF EXTERNAL COMPONENTS), system cost, and size constraints. 12 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4954 LM4954 www.ti.com SNAS292B – JUNE 2005 – REVISED APRIL 2013 SHUTDOWN FUNCTION In order to reduce power consumption while not in use, the LM4954 contains a shutdown pin to externally turn off the amplifier's bias circuitry. This shutdown feature turns the amplifier off when a logic low is placed on the shutdown pin. By switching the shutdown pin to ground, the LM4954 supply current draw will be minimized in idle mode. While the device will be disabled with shutdown pin voltages less than 0.4VDC, the idle current may be greater than the typical value of 0.01µA. (Idle current is measured with the shutdown pin tied to ground). The LM4954 has an internal 75kΩ pull-down resistor. If the shutdown pin is left floating the IC will automatically enter shutdown mode. PROPER SELECTION OF EXTERNAL COMPONENTS Proper selection of external components in applications using integrated power amplifiers is critical to optimize device and system performance. While the LM4954 is tolerant of external component combinations, consideration to component values must be used to maximize overall system quality. The LM4954 is unity-gain stable which gives the designer maximum system flexibility. The LM4954 should be used in low gain configurations to minimize THD+N values, and maximize the signal to noise ratio. Low gain configurations require large input signals to obtain a given output power. Input signals equal to or greater than 1 Vrms are available from sources such as audio codecs. Please refer to the section, AUDIO POWER AMPLIFIER DESIGN, for a more complete explanation of proper gain selection. Besides gain, one of the major considerations is the closed-loop bandwidth of the amplifier. To a large extent, the bandwidth is dictated by the choice of external components shown in Figure 1. The input coupling capacitor, Ci, forms a first order high pass filter which limits low frequency response. This value should be chosen based on needed frequency response for a few distinct reasons. Selection Of Input Capacitor Size Large input capacitors are both expensive and space hungry for portable designs. Clearly, a certain sized capacitor is needed to couple in low frequencies without severe attenuation. But in many cases the speakers used in portable systems, whether internal or external, have little ability to reproduce signals below 100Hz to 150Hz. Thus, using a large input capacitor may not increase actual system performance. In addition to system cost and size, click and pop performance is affected by the size of the input coupling capacitor, Ci. A larger input coupling capacitor requires more charge to reach its quiescent DC voltage (nominally 1/2VDD). This charge comes from the output via the feedback and is apt to create pops upon device enable. Thus, by minimizing the capacitor size based on necessary low frequency response, turn-on pops can be minimized. Besides minimizing the input capacitor size, careful consideration should be paid to the bypass capacitor value. Choosing CB equal to 2.2µF along with a small value of Ci (in the range of 0.1µF to 0.39µF), should produce a virtually clickless and popless shutdown function. While the device will function properly, (no oscillations or motorboating), with CB equal to 0.1µF. AUDIO POWER AMPLIFIER DESIGN A designer must first determine the minimum supply rail to obtain the specified output power. By extrapolating from the Output Power vs Supply Voltage graphs in the Typical Performance Characteristics section, the supply rail can be easily found. At this time, the designer must make sure that the power supply choice along with the output impedance does not violate the conditions explained in the POWER DISSIPATION section. Once the power dissipation equations have been addressed, the required differential gain can be determined from Equation 3 and Equation 4. (3) (4) AVD = (Rf/Ri) 2 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4954 13 LM4954 SNAS292B – JUNE 2005 – REVISED APRIL 2013 www.ti.com Figure 27. HIGHER GAIN AUDIO AMPLIFIER The LM4954 is unity-gain stable and requires no external components besides gain-setting resistors, an input coupling capacitor, and proper supply bypassing in the typical application. However, if a closed-loop differential gain of greater than 10 is required, a feedback capacitor (CF) may be needed as shown in Figure 27 to bandwidth limit the amplifier. This feedback capacitor creates a low pass filter that eliminates possible high frequency oscillations. Care should be taken when calculating the -3dB frequency in that an incorrect combination of RF and CF will cause rolloff before 20kHz. A typical combination of feedback resistor and capacitor that will not produce audio band high frequency rolloff is RF = 20kΩ and CF = 25pf. These components result in a -3dB point of approximately 320 kHz. To calculate the value of the capacitor for a given -3dB point, use Equation 5 below: CF = 1/(2πf3dBRF) (F) (5) Figure 28. DIFFERENTIAL AMPLIFIER CONFIGURATION FOR LM4954 14 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4954 LM4954 www.ti.com SNAS292B – JUNE 2005 – REVISED APRIL 2013 Figure 29. REFERENCE DESIGN BOARD SCHEMATIC Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4954 15 LM4954 SNAS292B – JUNE 2005 – REVISED APRIL 2013 www.ti.com LM4954 DSBGA BOARD ARTWORK (3) (3) 16 Figure 30. Composite View Figure 31. Silk Screen Figure 32. Top Layer Figure 33. Internal Layer 1, GND Figure 34. Internal Layer 2, VDD Figure 35. Bottom Layer All bumps have the same thermal resistance and contribute equally when used to lower thermal resistance. The θJA given in the Absolute Maximum Ratings section under Thermal Resistance is for the ITL package without any heat spreading planes on the PCB. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4954 LM4954 www.ti.com SNAS292B – JUNE 2005 – REVISED APRIL 2013 Table 1. Mono LM4954 Reference Design Boards Bill of Materials Designator Value Tolerance Part Description Ri 20kΩ 1% 1/10W, 1% 0805 Resistor Comment RF 20kΩ 1% 1/10W, 1% 0805 Resistor Ci 0.39μF 10% Ceramic 1206 Capacitor, 10% CS 2.2μF 10% 16V Tantalum 1210 Capacitor CB 2.2μF 10% CF Part not used 16V Tantalum 1210 Capacitor J1, J3, J4 0.100” 1x2 header, vertical mount Input, Output, Vdd/GND J2 0.100” 1x3 header, vertical mount Shutdown control PCB LAYOUT GUIDELINES This section provides practical guidelines for mixed signal PCB layout that involves various digital/analog power and ground traces. Designers should note that these are only "rule-of-thumb" recommendations and the actual results will depend heavily on the final layout. GENERAL MIXED SIGNAL LAYOUT RECOMMENDATIONS Power and Ground Circuits For a two layer mixed signal design, it is important to isolate the digital power and ground trace paths from the analog power and ground trace paths. Star trace routing techniques (bringing individual traces back to a central point rather than daisy chaining traces together in a serial manner) can have a major impact on low level signal performance. Star trace routing refers to using individual traces to feed power and ground to each circuit or even device. This technique requires a greater amount of design time but will not increase the final price of the board. The only extra parts required may be some jumpers. Single-Point Power / Ground Connections The analog power traces should be connected to the digital traces through a single point (link). A "Pi-filter" can be helpful in minimizing high frequency noise coupling between the analog and digital sections. It is further recommended to put digital and analog power traces over the corresponding digital and analog ground traces to minimize noise coupling. Placement of Digital and Analog Components All digital components and high-speed digital signals traces should be located as far away as possible from analog components and circuit traces. Avoiding Typical Design / Layout Problems Avoid ground loops or running digital and analog traces parallel to each other (side-by-side) on the same PCB layer. When traces must cross over each other do it at 90 degrees. Running digital and analog traces at 90 degrees to each other from the top to the bottom side as much as possible will minimize capacitive noise coupling and cross talk. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4954 17 LM4954 SNAS292B – JUNE 2005 – REVISED APRIL 2013 www.ti.com REVISION HISTORY Rev Date Description 1.1 4/29/05 Added curves 71 and 72. Edited Note 10. Changed Av = 26dB to 6dB under 7V EC table. Edited SHUTDOWN FUNCTION under the Application section. 1.2 6/08/05 Removed all the LLP pkg references. Changed TLA09XXX into YZR0009. Changed X1 and X2 measurements. 1.3 6/15/05 Fixed some typos. Initial WEB release. 1.4 6/20/05 Replaced curve 20129170 with 20129192. 1.5 6/22/05 Split Note 10 and added Note 11. Re-released to the WEB. Changes from Revision A (April 2013) to Revision B • 18 Page Changed layout of National Data Sheet to TI format .......................................................................................................... 17 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4954 PACKAGE OPTION ADDENDUM www.ti.com 10-Dec-2020 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) (4/5) (6) LM4954TL/NOPB ACTIVE DSBGA YZR 9 250 RoHS & Green SNAGCU Level-1-260C-UNLIM G F2 (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of