LM4673, LM4673SDBD, LM4673TMBD www.ti.com SNAS317D - DECEMBER 2005 - REVISED MAY 2013 LM4673 Filterless, 2.65W, Mono, Class D Audio Power Amplifier Check for Samples: LM4673, LM4673SDBD, LM4673TMBD FEATURES DESCRIPTION * * * * * * * * The LM4673 is a single supply, high efficiency, 2.65W, mono, Class D audio amplifier. A low noise, filterless PWM architecture eliminates the output filter, reducing external component count, board area consumption, system cost, and simplifying design. 1 2 Mono Class D Operation No Output Filter Required for Inductive Loads Externally Configurable Gain Very Fast Turn On Time: 17s (typ) Minimum External Components "Click and Pop" Suppression Circuitry Micro-Power Shutdown Mode Available in Space-Saving 0.4mm Pitch DSBGA and WSON Packages APPLICATIONS * * * Mobile Phones PDAs Portable Electronic Devices KEY SPECIFICATIONS * * * * * * * Efficiency at 3.6V, 400mW into 8 Speaker 88% (typ) Efficiency at 3.6V, 100mW into 8 Speaker 80% (typ) Efficiency at 5V, 1W into 8 Speaker 86% (typ) Quiescent Current, 3.6V Supply 2.1mA (typ) Total Shutdown Power Supply Current 0.01A (typ) Single Supply Range 2.4V to 5.5V PSRR, f = 217Hz 78dB The LM4673 is designed to meet the demands of mobile phones and other portable communication devices. Operating on a single 5V supply, it is capable of driving a 4 speaker load at a continuous average output of 2.1W with less than 1% THD+N. Its flexible power supply requirements allow operation from 2.4V to 5.5V. The LM4673 has high efficiency with speaker loads compared to a typical Class AB amplifier. With a 3.6V supply driving an 8 speaker, the IC's efficiency for a 100mW power level is 80%, reaching 88% at 400mW output power. The LM4673 features a low-power consumption shutdown mode. Shutdown may be enabled by driving the Shutdown pin to a logic low (GND). The gain of the LM4673 is externally configurable which allows independent gain control from multiple sources by summing the signals. Output short circuit and thermal overload protection prevent the device from damage during fault conditions. 1 2 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. All 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 (c) 2005-2013, Texas Instruments Incorporated LM4673, LM4673SDBD, LM4673TMBD SNAS317D - DECEMBER 2005 - REVISED MAY 2013 www.ti.com Typical Application Figure 1. Typical Audio Amplifier Application Circuit Connection Diagram GND IN+ A Vo1 VDD B PGND IN- C Vo2 1 3 2 SHUTDOWN PVDD Figure 2. 9-Bump DSBGA - Top View See YFQ0009 Package Figure 3. 8-Pin WSON - Top View See NGQ0008A 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 (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4673 LM4673SDBD LM4673TMBD LM4673, LM4673SDBD, LM4673TMBD www.ti.com SNAS317D - DECEMBER 2005 - REVISED MAY 2013 Absolute Maximum Ratings (1) (2) (3) Supply Voltage (1) 6.0V -65C to +150C Storage Temperature VDD + 0.3V V GND - 0.3V Voltage at Any Input Pin Power Dissipation (4) ESD Susceptibility, all other pins Internally Limited (5) 2.0kV ESD Susceptibility (6) 200V Junction Temperature (TJMAX) Thermal Resistance 150C JA (DSBGA) 99.1C/W JA (WSON) Soldering Information (1) (2) (3) (4) (5) (6) 73C/W See (SNVA009) "microSMD Wafers Level Chip Scale Package." 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 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. If Military/Aerospace specified devices are required, please contact the TI Sales Office/ Distributors for availability and specifications. The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, JA, and the ambient temperature TA. The maximum allowable power dissipation is PDMAX = (TJMAX-TA)/JA or the number given in Absolute Maximum Ratings, whichever is lower. For the LM4673, TJMAX = 150C. The typical JA is 99.1C/W for the DSBGA package. Human body model, 100pF discharged through a 1.5k resistor. Machine Model, 220pF - 240pF discharged through all pins. Operating Ratings (1) (2) Temperature Range TMIN TA TMAX -40C TA 85C 2.4V VDD 5.5V Supply Voltage (1) (2) 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 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. Copyright (c) 2005-2013, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: LM4673 LM4673SDBD LM4673TMBD 3 LM4673, LM4673SDBD, LM4673TMBD SNAS317D - DECEMBER 2005 - REVISED MAY 2013 www.ti.com Electrical Characteristics (1) (2) The following specifications apply for AV = 2V/V (RI = 150k), RL = 15H + 8 + 15H unless otherwise specified. Limits apply for TA = 25C. Symbol Parameter Conditions LM4673 Typical (3) Limit (4) (5) Units (Limits) |VOS| Differential Output Offset Voltage VI = 0V, AV = 2V/V, VDD = 2.4V to 5.0V |IIH| Logic High Input Current VDD = 5.0V, VI = 5.5V 17 100 A (max) |IIL| Logic Low Input Current VDD = 5.0V, VI = -0.3V 0.9 5 A (max) VIN = 0V, No Load, VDD = 5.0V 2.6 3.75 mA (max) VIN = 0V, No Load, VDD = 3.6V 2.1 2.9 mA VIN = 0V, No Load, VDD = 2.4V 1.7 2.3 mA (max) VIN = 0V, RL = 8, VDD = 5.0V 2.6 VIN = 0V, RL = 8, VDD = 3.6V 2.1 VIN = 0V, RL = 8, VDD = 2.4V 1.7 VSHUTDOWN = 0V VDD = 2.4V to 5.0V 0.01 1 A (max) IDD Quiescent Power Supply Current 5 mV (max) ISD Shutdown Current (6) VSDIH Shutdown voltage input high 1.4 V (min) VSDIL Shutdown voltage input low 0.4 V (max) ROSD Output Impedance 270k/RI 330k/RI V/V (min) V/V (max) VSHUTDOWN = 0.4V AV Gain RSD Resistance from Shutdown Pin to GND PO (1) (2) (3) (4) (5) (6) 4 100 300k/RI Output Power k 300 k RL = 15H + 4 + 15H THD = 10% (max) f = 1kHz, 22kHz BW VDD = 5V VDD = 3.6V VDD = 2.5V 2.65 1.3 550 W W mW RL = 15H + 4 + 15H THD = 1% (max) f = 1kHz, 22kHz BW VDD = 5V VDD = 3.6V VDD = 2.5V 2.15 1.06 450 W W mW 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 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. Typical specifications are specified at 25C and represent the parametric norm. Tested limits are guaranteed to TI's AOQL (Average Outgoing Quality Level). Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis. Shutdown current is measured in a normal room environment. Exposure to direct sunlight will increase ISD by a maximum of 2A. The Shutdown pin should be driven as close as possible to GND for minimal shutdown current and to VDD for the best THD performance in PLAY mode. See the Application Information section under SHUTDOWN FUNCTION for more information. Submit Documentation Feedback Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4673 LM4673SDBD LM4673TMBD LM4673, LM4673SDBD, LM4673TMBD www.ti.com SNAS317D - DECEMBER 2005 - REVISED MAY 2013 Electrical Characteristics(1)(2) (continued) The following specifications apply for AV = 2V/V (RI = 150k), RL = 15H + 8 + 15H unless otherwise specified. Limits apply for TA = 25C. Symbol Parameter Conditions LM4673 Typical (3) Limit (4) (5) Units (Limits) RL = 15H + 8 + 15H THD = 10% (max) f = 1kHz, 22kHz BW PO Output Power THD+N PSRR SNR OUT VDD = 5V 1.7 W VDD = 3.6V 870 mW VDD = 2.5V 350 mW RL = 15H + 8 + 15H THD = 1% (max) f = 1kHz, 22kHz BW Total Harmonic Distortion + Noise Power Supply Rejection Ratio (Input Referred) Signal to Noise Ratio Output Noise (Input Referred) VDD = 5V 1.24 VDD = 3.6V 650 300 mW VDD = 5V, PO = 0.1W, f = 1kHz 0.03 % VDD = 3.6V, PO = 0.1W, f = 1kHz 0.02 % VDD = 2.5V, PO = 0.1W, f = 1kHz 0.02 % VRipple = 200mVPP Sine, fRipple = 217Hz, VDD = 3.6, 5V Inputs to AC GND, CI = 2F 78 dB VRipple = 200mVPP Sine, fRipple = 1kHz, VDD = 3.6, 5V Inputs to AC GND, CI = 2F 72 dB VDD = 5V, PO = 1WRMS 97 dB VDD = 3.6V, f = 20Hz - 20kHz Inputs to AC GND, CI = 2F No Weighting 30 VRMS VDD = 3.6V, Inputs to AC GND CI = 2F, A Weighted 23 VRMS 70 dB Common Mode Rejection Ratio (Input Referred) VDD = 3.6V, VRipple = 1VPP Sine fRipple = 217Hz TWU Wake-up Time VDD = 3.6V TSD Shutdown Time Efficiency mW VDD = 2.5V CMRR W 600 17 s 140 s VDD = 3.6V, POUT = 400mW RL = 8 88 % VDD = 5V, POUT = 1W RL = 8 86 % External Components Description (Figure 1) Components Functional Description 1. 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. 2. CI Input AC coupling capacitor which blocks the DC voltage at the amplifier's input terminals. Copyright (c) 2005-2013, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: LM4673 LM4673SDBD LM4673TMBD 5 LM4673, LM4673SDBD, LM4673TMBD SNAS317D - DECEMBER 2005 - REVISED MAY 2013 www.ti.com Typical Performance Characteristics The performance graphs were taken using the Audio Precision AUX-0025 Switching Amplifier measurement Filter in series with the LC filter on the demo board. THD + N vs Output Power f = 1kHz, RL = 8 THD + N vs Output Power f = 1kHz, RL = 4 100 100 VDD = 5V VDD = 5V 10 10 VDD = 3.6V THD+N (%) THD+N (%) VDD = 3.6V VDD = 2.5V 1 VDD = 2.5V 1 0.1 0.1 0.01 0.001 0.01 0.1 1 0.01 0.001 10 1 10 OUTPUT POWER (W) Figure 5. THD + N vs Frequency VDD = 2.5V, POUT = 100mW, RL = 8 THD + N vs Frequency VDD = 3.6V, POUT = 150mW, RL = 8 100 100 10 10 1 0.1 0.01 0.001 10 6 0.1 Figure 4. THD+N (%) THD+N (%) OUTPUT POWER (W) 0.01 1 0.1 0.01 100 1000 10000 100000 0.001 10 100 1000 10000 FREQUENCY (Hz) FREQUENCY (Hz) Figure 6. Figure 7. Submit Documentation Feedback 100000 Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4673 LM4673SDBD LM4673TMBD LM4673, LM4673SDBD, LM4673TMBD www.ti.com SNAS317D - DECEMBER 2005 - REVISED MAY 2013 Typical Performance Characteristics (continued) The performance graphs were taken using the Audio Precision AUX-0025 Switching Amplifier measurement Filter in series with the LC filter on the demo board. THD + N vs Frequency VDD = 2.5V, POUT = 100mW, RL = 4 100 100 10 10 THD+N (%) THD+N (%) THD + N vs Frequency VDD = 5V, POUT = 200mW, RL = 8 1 0.1 0.01 0.1 0.01 0.001 10 100 1000 10000 100000 0.001 10 100 1000 10000 100000 FREQUENCY (Hz) FREQUENCY (Hz) Figure 8. Figure 9. THD + N vs Frequency VDD = 3.6V, POUT = 100mW, RL = 4 THD + N vs Frequency VDD = 5V, POUT = 150mW, RL = 4 100 100 10 10 THD+N (%) THD+N (%) 1 1 0.1 0.01 0.001 10 1 0.1 0.01 100 1000 10000 100000 0.001 10 100 1000 10000 FREQUENCY (Hz) FREQUENCY (Hz) Figure 10. Figure 11. Copyright (c) 2005-2013, Texas Instruments Incorporated 100000 Submit Documentation Feedback Product Folder Links: LM4673 LM4673SDBD LM4673TMBD 7 LM4673, LM4673SDBD, LM4673TMBD SNAS317D - DECEMBER 2005 - REVISED MAY 2013 www.ti.com Typical Performance Characteristics (continued) The performance graphs were taken using the Audio Precision AUX-0025 Switching Amplifier measurement Filter in series with the LC filter on the demo board. Efficiency vs. Output Power RL = 4, f = 1kHz Efficiency vs. Output Power RL = 8, f = 1kHz 100 100 90 90 V DD = 5V VDD = 5V 80 70 EFFICIENCY (%) EFFICIENCY (%) 80 V DD = 3.6V 60 V DD = 2.5V 50 40 30 70 60 40 30 20 10 10 0 500 1000 1500 2000 V DD = 2.5V 50 20 0 VDD = 3.6V 0 2500 0 250 500 750 1000 1250 1500 OUTPUT POWER (mW) OUTPUT POWER (mW) Figure 12. Figure 13. Power Dissipation vs. Output Power RL = 4, f = 1kHz Power Dissipation vs. Output Power RL = 8, f = 1kHz 200 600 VDD = 3.6V 400 V DD = 2.5V 300 200 VDD = 5V 100 POWER DISSIPATION (mW) POWER DISSIPATION (%) 180 500 VDD = 5V 160 140 120 VDD = 3.6V 100 80 60 40 20 0 V DD = 2.5V 0 0 200 400 600 800 1000 1200 OUTPUT POWER (mW) 0 250 500 Submit Documentation Feedback 1000 1250 1500 OUTPUT POWER (mW) Figure 14. 8 750 Figure 15. Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4673 LM4673SDBD LM4673TMBD LM4673, LM4673SDBD, LM4673TMBD www.ti.com SNAS317D - DECEMBER 2005 - REVISED MAY 2013 Typical Performance Characteristics (continued) The performance graphs were taken using the Audio Precision AUX-0025 Switching Amplifier measurement Filter in series with the LC filter on the demo board. Output Power vs. Supply Voltage RL = 8, f = 1kHz 4000 2000 3500 1750 OUTPUT POWER (mW) OUTPUT POWER (mW) Output Power vs. Supply Voltage RL = 4, f = 1kHz 3000 2500 THD+N = 10% 2000 1500 THD+N = 1% 1000 1250 THD+N = 10% 1000 750 THD+N = 1% 500 250 500 0 2.5 1500 0 3 3.5 4 4.5 5 5.5 2.5 3.5 4 4.5 5 5.5 SUPPLY VOLTAGE (V) Figure 16. Figure 17. PSRR vs. Frequency VDD = 3.6V ,VRIPPLE = 200mVP-P, RL = 8 CMRR vs. Frequency VDD = 3.6V, VCM = 1VP-P, RL = 8 0 0 -10 -10 -20 -20 -30 -30 CMRR(dB) PSRR (dB) SUPPLY VOLTAGE (V) 3 -40 -50 -40 -50 -60 -60 -70 -70 -80 -80 -90 10 100 1000 10000 100000 -90 10 100 1000 10000 FREQUENCY (Hz) FREQUENCY (Hz) Figure 18. Figure 19. Copyright (c) 2005-2013, Texas Instruments Incorporated 100000 Submit Documentation Feedback Product Folder Links: LM4673 LM4673SDBD LM4673TMBD 9 LM4673, LM4673SDBD, LM4673TMBD SNAS317D - DECEMBER 2005 - REVISED MAY 2013 www.ti.com Typical Performance Characteristics (continued) The performance graphs were taken using the Audio Precision AUX-0025 Switching Amplifier measurement Filter in series with the LC filter on the demo board. Supply Current vs. Supply Voltage No Load 4 SUPPLY CURRENT (mA) 3.5 3 2.5 2 1.5 1 0.5 0 2.5 3 3.5 4 4.5 5 5.5 SUPPLY VOLTAGE (V) Figure 20. 10 Submit Documentation Feedback Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4673 LM4673SDBD LM4673TMBD LM4673, LM4673SDBD, LM4673TMBD www.ti.com SNAS317D - DECEMBER 2005 - REVISED MAY 2013 APPLICATION INFORMATION GENERAL AMPLIFIER FUNCTION The LM4673 features a filterless modulation scheme. The differential outputs of the device switch at 300kHz from VDD to GND. When there is no input signal applied, the two outputs (VO1 and VO2) switch with a 50% duty cycle, with both outputs in phase. Because the outputs of the LM4673 are differential, the two signals cancel each other. This results in no net voltage across the speaker, thus there is no load current during an idle state, conserving power. With an input signal applied, the duty cycle (pulse width) of the LM4673 outputs changes. For increasing output voltages, the duty cycle of VO1 increases, while the duty cycle of VO2 decreases. For decreasing output voltages, the converse occurs, the duty cycle of VO2 increases while the duty cycle of VO1 decreases. The difference between the two pulse widths yields the differential output voltage. POWER DISSIPATION AND EFFICIENCY In general terms, efficiency is considered to be the ratio of useful work output divided by the total energy required to produce it with the difference being the power dissipated, typically, in the IC. The key here is "useful" work. For audio systems, the energy delivered in the audible bands is considered useful including the distortion products of the input signal. Sub-sonic (DC) and super-sonic components (>22kHz) are not useful. The difference between the power flowing from the power supply and the audio band power being transduced is dissipated in the LM4673 and in the transducer load. The amount of power dissipation in the LM4673 is very low. This is because the ON resistance of the switches used to form the output waveforms is typically less than 0.25. This leaves only the transducer load as a potential "sink" for the small excess of input power over audio band output power. The LM4673 dissipates only a fraction of the excess power requiring no additional PCB area or copper plane to act as a heat sink. DIFFERENTIAL AMPLIFIER EXPLANATION As logic supply voltages continue to shrink, designers are increasingly turning to differential analog signal handling to preserve signal to noise ratios with restricted voltage swing. The LM4673 is a fully differential amplifier that features differential input and output stages. A differential amplifier amplifies the difference between the two input signals. Traditional audio power amplifiers have typically offered only single-ended inputs resulting in a 6dB reduction in signal to noise ratio relative to differential inputs. The LM4673 also offers the possibility of DC input coupling which eliminates the two external AC coupling, DC blocking capacitors. The LM4673 can be used, however, as a single ended input amplifier while still retaining it's fully differential benefits. In fact, completely unrelated signals may be placed on the input pins. The LM4673 simply amplifies the difference between the signals. A major benefit of a differential amplifier is the improved common mode rejection ratio (CMRR) over single input amplifiers. The common-mode rejection characteristic of the differential amplifier reduces sensitivity to ground offset related noise injection, especially important in high noise applications. PCB LAYOUT CONSIDERATIONS As output power increases, interconnect resistance (PCB traces and wires) between the amplifier, load and power supply create a voltage drop. The voltage loss on the traces between the LM4673 and the load results is lower output power and decreased efficiency. Higher trace resistance between the supply and the LM4673 has the same effect as a poorly regulated supply, increased ripple on the supply line also reducing the peak output power. The effects of residual trace resistance increases as output current increases due to higher output power, decreased load impedance or both. To maintain the highest output voltage swing and corresponding peak output power, the PCB traces that connect the output pins to the load and the supply pins to the power supply should be as wide as possible to minimize trace resistance. The use of power and ground planes will give the best THD+N performance. While reducing trace resistance, the use of power planes also creates parasite capacitors that help to filter the power supply line. Copyright (c) 2005-2013, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: LM4673 LM4673SDBD LM4673TMBD 11 LM4673, LM4673SDBD, LM4673TMBD SNAS317D - DECEMBER 2005 - REVISED MAY 2013 www.ti.com The inductive nature of the transducer load can also result in overshoot on one or both edges, clamped by the parasitic diodes to GND and VDD in each case. From an EMI standpoint, this is an aggressive waveform that can radiate or conduct to other components in the system and cause interference. It is essential to keep the power and output traces short and well shielded if possible. Use of ground planes, beads, and micro-strip layout techniques are all useful in preventing unwanted interference. As the distance from the LM4673 and the speaker increase, the amount of EMI radiation will increase since the output wires or traces acting as antenna become more efficient with length. What is acceptable EMI is highly application specific. Ferrite chip inductors placed close to the LM4673 may be needed to reduce EMI radiation. The value of the ferrite chip is very application specific. POWER SUPPLY BYPASSING As with any power amplifier, proper supply bypassing is critical for low noise performance and high power supply rejection ratio (PSRR). The capacitor (CS) location should be as close as possible to the LM4673. Typical applications employ a voltage regulator with a 10F and a 0.1F bypass capacitors that increase supply stability. These capacitors do not eliminate the need for bypassing on the supply pin of the LM4673. A 4.7F tantalum capacitor is recommended. SHUTDOWN FUNCTION In order to reduce power consumption while not in use, the LM4673 contains shutdown circuitry that reduces current draw to less than 0.01A. The trigger point for shutdown is shown as a typical value in the Electrical Characteristics Tables and in the Shutdown Hysteresis Voltage graphs found in the Typical Performance Characteristics section. It is best to switch between ground and supply for minimum current usage while in the shutdown state. While the LM4673 may be disabled with shutdown voltages in between ground and supply, the idle current will be greater than the typical 0.01A value. The LM4673 has an internal resistor connected between GND and Shutdown pins. The purpose of this resistor is to eliminate any unwanted state changes when the Shutdown pin is floating. The LM4673 will enter the shutdown state when the Shutdown pin is left floating or if not floating, when the shutdown voltage has crossed the threshold. To minimize the supply current while in the shutdown state, the Shutdown pin should be driven to GND or left floating. If the Shutdown pin is not driven to GND, the amount of additional resistor current due to the internal shutdown resistor can be found by Equation 1 below. (VSD - GND) / 300k (1) With only a 0.5V difference, an additional 1.7A of current will be drawn while in the shutdown state. PROPER SELECTION OF EXTERNAL COMPONENTS The gain of the LM4673 is set by the external resistors, Ri in Typical Application, The Gain is given by Equation 2 below. Best THD+N performance is achieved with a gain of 2V/V (6dB). AV = 2 * 150 k / Ri (V/V) (2) It is recommended that resistors with 1% tolerance or better be used to set the gain of the LM4673. The Ri resistors should be placed close to the input pins of the LM4673. Keeping the input traces close to each other and of the same length in a high noise environment will aid in noise rejection due to the good CMRR of the LM4673. Noise coupled onto input traces which are physically close to each other will be common mode and easily rejected by the LM4673. Input capacitors may be needed for some applications or when the source is single-ended (see Figure 22, Figure 24). Input capacitors are needed to block any DC voltage at the source so that the DC voltage seen between the input terminals of the LM4673 is 0V. Input capacitors create a high-pass filter with the input resistors, Ri. The -3dB point of the high-pass filter is found using Equation 3 below. fC = 1 / (2Ri Ci ) (Hz) (3) The input capacitors may also be used to remove low audio frequencies. Small speakers cannot reproduce low bass frequencies so filtering may be desired . When the LM4673 is using a single-ended source, power supply noise on the ground is seen as an input signal by the +IN input pin that is capacitor coupled to ground (See Figure 24 - Figure 26). Setting the high-pass filter point above the power supply noise frequencies, 217Hz in a GSM phone, for example, will filter out this noise so it is not amplified and heard on the output. Capacitors with a tolerance of 10% or better are recommended for impedance matching. 12 Submit Documentation Feedback Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4673 LM4673SDBD LM4673TMBD LM4673, LM4673SDBD, LM4673TMBD www.ti.com SNAS317D - DECEMBER 2005 - REVISED MAY 2013 DIFFERENTIAL CIRCUIT CONFIGURATIONS The LM4673 can be used in many different circuit configurations. The simplest and best performing is the DC coupled, differential input configuration shown in Figure 21. Equation 2 above is used to determine the value of the Ri resistors for a desired gain. Input capacitors can be used in a differential configuration as shown in Figure 22. Equation 3 above is used to determine the value of the Ci capacitors for a desired frequency response due to the high-pass filter created by Ci and Ri. Equation 2 above is used to determine the value of the Ri resistors for a desired gain. The LM4673 can be used to amplify more than one audio source. Figure 23 shows a dual differential input configuration. The gain for each input can be independently set for maximum design flexibility using the Ri resistors for each input and Equation 2. Input capacitors can be used with one or more sources as well to have different frequency responses depending on the source or if a DC voltage needs to be blocked from a source. SINGLE-ENDED CIRCUIT CONFIGURATIONS The LM4673 can also be used with single-ended sources but input capacitors will be needed to block any DC at the input terminals. Figure 24 shows the typical single-ended application configuration. The equations for Gain, Equation 2, and frequency response, Equation 3, hold for the single-ended configuration as shown in Figure 24. When using more than one single-ended source as shown in Figure 25, the impedance seen from each input terminal should be equal. To find the correct values for Ci3 and Ri3 connected to the +IN input pin the equivalent impedance of all the single-ended sources are calculated. The single-ended sources are in parallel to each other. The equivalent capacitor and resistor, Ci3 and Ri3, are found by calculating the parallel combination of all Civalues and then all Ri values. Equation 4 and Equation 5 below are for any number of single-ended sources. Ci3 = Ci1 + Ci2 + Cin ... (F) Ri3 = 1 / (1/Ri1 + 1/Ri2 + 1/Rin ...) () (4) (5) The LM4673 may also use a combination of single-ended and differential sources. A typical application with one single-ended source and one differential source is shown in Figure 26. Using the principle of superposition, the external component values can be determined with the above equations corresponding to the configuration. Figure 21. Differential Input Configuration Copyright (c) 2005-2013, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: LM4673 LM4673SDBD LM4673TMBD 13 LM4673, LM4673SDBD, LM4673TMBD SNAS317D - DECEMBER 2005 - REVISED MAY 2013 www.ti.com Figure 22. Differential Input Configuration with Input Capacitors Figure 23. Dual Differential Input Configuration Figure 24. Single-Ended Input Configuration 14 Submit Documentation Feedback Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4673 LM4673SDBD LM4673TMBD LM4673, LM4673SDBD, LM4673TMBD www.ti.com SNAS317D - DECEMBER 2005 - REVISED MAY 2013 Figure 25. Dual Single-Ended Input Configuration Figure 26. Dual Input with a Single-Ended Input and a Differential Input Copyright (c) 2005-2013, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: LM4673 LM4673SDBD LM4673TMBD 15 LM4673, LM4673SDBD, LM4673TMBD SNAS317D - DECEMBER 2005 - REVISED MAY 2013 www.ti.com REFERENCE DESIGN BOARD SCHEMATIC In addition to the minimal parts required for the application circuit, a measurement filter is provided on the evaluation circuit board so that conventional audio measurements can be conveniently made without additional equipment. This is a balanced input, grounded differential output low pass filter with a 3dB frequency of approximately 35kHz and an on board termination resistor of 300 (see schematic). Note that the capacitive load elements are returned to ground. This is not optimal for common mode rejection purposes, but due to the independent pulse format at each output there is a significant amount of high frequency common mode component on the outputs. The grounded capacitive filter elements attenuate this component at the board to reduce the high frequency CMRR requirement placed on the analysis instruments. Even with the grounded filter the audio signal is still differential, necessitating a differential input on any analysis instrument connected to it. Most lab instruments that feature BNC connectors on their inputs are NOT differential responding because the ring of the BNC is usually grounded. The commonly used Audio Precision analyzer is differential, but its ability to accurately reject high frequency signals is questionable necessitating the on board measurement filter. When in doubt or when the signal needs to be single-ended, use an audio signal transformer to convert the differential output to a single ended output. Depending on the audio transformer's characteristics, there may be some attenuation of the audio signal which needs to be taken into account for correct measurement of performance. Measurements made at the output of the measurement filter suffer attenuation relative to the primary, unfiltered outputs even at audio frequencies. This is due to the resistance of the inductors interacting with the termination resistor (300) and is typically about -0.25dB (3%). In other words, the voltage levels (and corresponding power levels) indicated through the measurement filter are slightly lower than those that actually occur at the load placed on the unfiltered outputs. This small loss in the filter for measurement gives a lower output power reading than what is really occurring on the unfiltered outputs and its load. 16 Submit Documentation Feedback Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4673 LM4673SDBD LM4673TMBD LM4673, LM4673SDBD, LM4673TMBD www.ti.com SNAS317D - DECEMBER 2005 - REVISED MAY 2013 LM4673SD Demo Board Artwork Top Silkscreen Top Layer Composite View Internal Layer 1 Internal Layer 2 Bottom Silkscreen Copyright (c) 2005-2013, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: LM4673 LM4673SDBD LM4673TMBD 17 LM4673, LM4673SDBD, LM4673TMBD SNAS317D - DECEMBER 2005 - REVISED MAY 2013 www.ti.com Bottom Layer LM4673TM Demo Board Artwork Top Silkscreen 18 Submit Documentation Feedback Top Layer Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4673 LM4673SDBD LM4673TMBD LM4673, LM4673SDBD, LM4673TMBD www.ti.com SNAS317D - DECEMBER 2005 - REVISED MAY 2013 Composite View Internal Layer 1 Internal Layer 2 Bottom Silkscreen Copyright (c) 2005-2013, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: LM4673 LM4673SDBD LM4673TMBD 19 LM4673, LM4673SDBD, LM4673TMBD SNAS317D - DECEMBER 2005 - REVISED MAY 2013 www.ti.com Bottom Layer 20 Submit Documentation Feedback Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4673 LM4673SDBD LM4673TMBD LM4673, LM4673SDBD, LM4673TMBD www.ti.com SNAS317D - DECEMBER 2005 - REVISED MAY 2013 REVISION HISTORY Rev Date Description 1.0 12/16/05 Initial WEB released. 1.1 02/28/06 Taken out "Future Product", then re-WEBd the datasheet. 1.2 04/06/06 Added the TM and SD demo boards, then released to the WEB (per Royce). 1.3 11/01/07 Deleted a sentence under the SHUTDOWN FUNCTION section. Changes from Revision C (May 2013) to Revision D * Page Changed layout of National Data Sheet to TI format .......................................................................................................... 19 Copyright (c) 2005-2013, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: LM4673 LM4673SDBD LM4673TMBD 21 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) LM4673SD/NOPB ACTIVE WSON NGQ 8 1000 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 L4673 LM4673TM/NOPB ACTIVE DSBGA YFQ 9 250 RoHS & Green SNAGCU Level-1-260C-UNLIM -40 to 85 G G4 LM4673TMX/NOPB ACTIVE DSBGA YFQ 9 3000 RoHS & Green SNAGCU Level-1-260C-UNLIM -40 to 85 G G4 (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 <=1000ppm threshold. Antimony trioxide based flame retardants must also meet the <=1000ppm threshold requirement. (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com 10-Dec-2020 In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. Addendum-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 12-Aug-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing LM4673SD/NOPB WSON NGQ 8 LM4673TM/NOPB DSBGA YFQ LM4673TMX/NOPB DSBGA YFQ SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 1000 178.0 12.4 3.3 3.3 1.0 8.0 12.0 Q1 9 250 178.0 8.4 1.5 1.5 0.76 4.0 8.0 Q1 9 3000 178.0 8.4 1.5 1.5 0.76 4.0 8.0 Q1 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 12-Aug-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM4673SD/NOPB WSON NGQ 8 1000 210.0 185.0 35.0 LM4673TM/NOPB DSBGA YFQ 9 250 210.0 185.0 35.0 LM4673TMX/NOPB DSBGA YFQ 9 3000 210.0 185.0 35.0 Pack Materials-Page 2 MECHANICAL DATA YFQ0009xxx D 0.6000.075 E TMD09XXX (Rev A) D: Max = 1.397 mm, Min =1.336 mm E: Max = 1.397 mm, Min =1.336 mm 4215077/A NOTES: A. All linear dimensions are in millimeters. Dimensioning and tolerancing per ASME Y14.5M-1994. B. This drawing is subject to change without notice. www.ti.com 12/12 PACKAGE OUTLINE NGQ0008A WSON - 0.8 mm max height SCALE 4.000 PLASTIC SMALL OUTLINE - NO LEAD 3.1 2.9 B A PIN 1 INDEX AREA 3.1 2.9 C 0.8 0.7 SEATING PLANE 0.08 C 1.6 0.1 (0.1) TYP SYMM EXPOSED THERMAL PAD 0.05 0.00 4 5 SYMM 9 2X 1.5 2 0.1 8 1 6X 0.5 8X PIN 1 ID 8X 0.5 0.3 0.3 0.2 0.1 0.05 C A B C 4214922/A 03/2018 NOTES: 1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing per ASME Y14.5M. 2. This drawing is subject to change without notice. 3. The package thermal pad must be soldered to the printed circuit board for thermal and mechanical performance. www.ti.com EXAMPLE BOARD LAYOUT NGQ0008A WSON - 0.8 mm max height PLASTIC SMALL OUTLINE - NO LEAD (1.6) SYMM 8X (0.6) 1 8 (0.75) 8X (0.25) 9 SYMM (2) 6X (0.5) 5 4 (R0.05) TYP ( 0.2) VIA TYP (2.8) LAND PATTERN EXAMPLE EXPOSED METAL SHOWN SCALE:20X 0.07 MIN ALL AROUND 0.07 MAX ALL AROUND EXPOSED METAL EXPOSED METAL SOLDER MASK OPENING METAL METAL UNDER SOLDER MASK NON SOLDER MASK DEFINED (PREFERRED) SOLDER MASK OPENING SOLDER MASK DEFINED SOLDER MASK DETAILS 4214922/A 03/2018 NOTES: (continued) 4. This package is designed to be soldered to a thermal pad on the board. For more information, see Texas Instruments literature number SLUA271 (www.ti.com/lit/slua271). 5. Vias are optional depending on application, refer to device data sheet. If any vias are implemented, refer to their locations shown on this view. It is recommended that vias under paste be filled, plugged or tented. www.ti.com EXAMPLE STENCIL DESIGN NGQ0008A WSON - 0.8 mm max height PLASTIC SMALL OUTLINE - NO LEAD 8X (0.6) SYMM 9 METAL TYP 8 1 8X (0.25) SYMM (1.79) 6X (0.5) 5 4 (R0.05) TYP (1.47) (2.8) SOLDER PASTE EXAMPLE BASED ON 0.1 mm THICK STENCIL EXPOSED PAD 9: 82% PRINTED SOLDER COVERAGE BY AREA UNDER PACKAGE SCALE:20X 4214922/A 03/2018 NOTES: (continued) 6. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. 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