LM4941TMBD

LM4941, LM4941SDBD, LM4941TMBD www.ti.com SNAS347C – JUNE 2006 – REVISED MAY 2013 LM4941 1.25 Watt Fully Differential Audio Power Amplifier With RF Suppression and Shutdown Check for Samples: LM4941, LM4941SDBD, LM4941TMBD FEATURES DESCRIPTION • The LM4941 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 1.25 watts of continuous average power to a 8Ω load with less than 1% distortion (THD+N) from a 5VDC power supply. The LM4941 does not require output coupling capacitors or bootstrap capacitors, and therefore is ideally suited for mobile phone and other small form factor applications where minimal PCB space is a primary requirement. 1 2 • • • • • • • Improved RF Suppression, By Up to 20dB Over Previous Designs in Selected Applications Fully Differential Amplification Available in Space-Saving DSBGA 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 2.4 - 5.5V Operation No Output Coupling Capacitors, Snubber Networks or Bootstrap Capacitors Required APPLICATIONS • • • Mobile Phones PDAs Portable Electronic Devices KEY SPECIFICATIONS • • • • Improved PSRR at 217Hz 95dB (typ) Power Output, VDD = 5.0V, RL = 8Ω, 1% THD+N 1.25W (typ) Power Output, VDD = 3.0V, RL = 8Ω, 1% THD+N 430mW (typ) Shutdown Current 0.1µA (typ) The LM4941 also features proprietary internal circuitry that suppresses the coupling of RF signals into the chip. This is important because certain types of RF signals (such as GSM) can couple into audio amplifiers in such a way that part of the signal is heard through the speaker. The RF suppression circuitry in the LM4941 makes it well-suited for portable applications in which strong RF signals generated by an antenna from or a cellular phone or other portable electronic device may couple audibly into the amplifier. Other features include a low-power consumption shutdown mode, internal thermal shutdown protection, and advanced pop & click circuitry. 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 © 2006–2013, Texas Instruments Incorporated LM4941, LM4941SDBD, LM4941TMBD SNAS347C – JUNE 2006 – REVISED MAY 2013 www.ti.com Typical Application VDD CS 1 PF RF1 + 20 k: Ri1 20 k: -IN - Differential Input + Bias SHUTDOWN 1.0 PF + Differential Input CB RL Common Mode 8: - BYP VO- + +IN Ri2 VO+ 20 k: GND RF2 20 k: Figure 1. Typical Audio Amplifier Application Circuit Connection Diagram xxx xxx 3 2 1 OUT- +IN VDD OUT+ -IN 1 8 OUT+ BYP 2 7 VDD SHDN 3 6 GND +IN 4 5 OUT- -IN GND SHDN GND BYP A B C Figure 3. 8-Pin WSON - Top View See NGS0008C Package Figure 2. 9-Bump DSBGA - Top View See YFQ0009 Package 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 © 2006–2013, Texas Instruments Incorporated Product Folder Links: LM4941 LM4941SDBD LM4941TMBD LM4941, LM4941SDBD, LM4941TMBD www.ti.com SNAS347C – JUNE 2006 – REVISED MAY 2013 Absolute Maximum Ratings (1) (2) (3) Supply Voltage 6.0V −65°C to +150°C Storage Temperature −0.3V to VDD +0.3V Input Voltage Power Dissipation (4) (5) ESD Susceptibility Internally Limited (6) 2000V ESD Susceptibility (7) 200V Junction Temperature 150°C θJA (TM) Thermal Resistance 100°C/W θJA (WSON) 71°C/W Soldering Information (1) (2) (3) (4) (5) (6) (7) See AN-1187 (SNOA401) 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 TI 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 LM4941, see power derating curve for additional information. Maximum Power Dissipation (PDMAX) in the device occurs at an output power level significantly below full output power. PDMAX can be calculated using Equation 3 shown in the Application section. It may also be obtained from the Power Dissipation graphs. Human body model, 100pF discharged through a 1.5kΩ resistor. Machine Model, 220pF – 240pF discharged through all pins. Operating Ratings Temperature Range TMIN ≤ TA ≤ TMAX −40°C ≤ TA ≤ 85°C 2.4V ≤ VDD ≤ 5.5V Supply Voltage Electrical Characteristics VDD = 5V (1) (2) The following specifications apply for VDD = 5V, AV = 1V/V, and 8Ω load unless otherwise specified. Limits apply for TA = 25°C. Symbol Parameter Conditions LM4941 Typical (3) Limit (4) (5) Units (Limits) IDD Quiescent Power Supply Current VIN = 0V, no load VIN = 0V, RL = 8Ω 1.7 1.7 2.3 mA (max) mA ISD Shutdown Current VSHDN = GND 0.1 0.8 µA (max) THD+N = 1% (max); f = 1 kHz RL = 8Ω 1.25 1.15 W (min) THD+N = 10% (max); f = 1 kHz RL = 8Ω 1.54 W PO = 0.7 W; f = 1kHz 0.04 % PO Output Power THD+N Total Harmonic Distortion + Noise VRIPPLE = 200mVP-P Sine PSRR (1) (2) (3) (4) (5) (6) Power Supply Rejection Ratio f = 217Hz (6) 95 f = 1kHz (6) 90 80 dB (min) dB 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. Typicals are measured at 25°C and represent the parametric norm. Limits are specified to TI's AOQL (Average Outgoing Quality Level). Datasheet min/max specification limits are specified by design, test, or statistical analysis. 10Ω terminated input. Copyright © 2006–2013, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: LM4941 LM4941SDBD LM4941TMBD 3 LM4941, LM4941SDBD, LM4941TMBD SNAS347C – JUNE 2006 – REVISED MAY 2013 www.ti.com Electrical Characteristics VDD = 5V(1)(2) (continued) The following specifications apply for VDD = 5V, AV = 1V/V, and 8Ω load unless otherwise specified. Limits apply for TA = 25°C. Symbol Parameter Conditions LM4941 Typical (3) f = 217Hz, VCM = 200mVP-P Sine 70 f = 20Hz–20kHz , VCM = 200mVpp 70 VIN = 0V 2 Limit (4) (5) Units (Limits) dB CMRR Common-Mode Rejection Ratio VOS Output Offset Voltage VSDIH Shutdown Voltage Input High VSDIL Shutdown Voltage Input Low SNR Signal-to-Noise Ratio PO = 1W, f = 1kHz 108 dB TWU Wake-up Time from Shutdown CBYPASS = 1μF 12 ms dB 6 mV (max) 1.4 V (min) 0.4 V (max) Electrical Characteristics VDD = 3V (1) (2) The following specifications apply for VDD = 3V, AV = 1V/V, and 8Ω load unless otherwise specified. Limits apply for TA = 25°C. Symbol Parameter Conditions LM4941 Typical (3) Limit (4) (5) Units (Limits) IDD Quiescent Power Supply Current VIN = 0V, no load VIN = 0V, RL = 8Ω 1.6 1.6 2.2 mA (max) mA ISD Shutdown Current VSHDN = GND 0.1 0.8 µA (max) THD+N = 1% (max); f = 1 kHz RL = 8Ω 0.43 W THD+N = 10% (max); f = 1 kHz RL = 8Ω 0.54 W PO = 0.25W; f = 1kHz 0.05 % f = 217Hz (6) 95 dB f = 1kHz (6) 90 dB dB PO Output Power THD+N Total Harmonic Distortion + Noise PSRR Power Supply Rejection Ratio VRIPPLE = 200mVPP Sine CMRR Common-Mode Rejection Ratio f = 217Hz, VCM = 200mVPP Sine 70 VOS Output Offset Voltage VIN = 0V 2 VSDIH Shutdown Voltage Input High 1.4 V (min) VSDIL Shutdown Voltage Input Low 0.4 V (max) TWU Wake-up Time from Shutdown (1) (2) (3) (4) (5) (6) 4 CBYPASS = 1μF 8 6 mV (max) ms 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. Typicals are measured at 25°C and represent the parametric norm. Limits are specified to TI's AOQL (Average Outgoing Quality Level). Datasheet min/max specification limits are specified by design, test, or statistical analysis. 10Ω terminated input. Submit Documentation Feedback Copyright © 2006–2013, Texas Instruments Incorporated Product Folder Links: LM4941 LM4941SDBD LM4941TMBD LM4941, LM4941SDBD, LM4941TMBD www.ti.com SNAS347C – JUNE 2006 – REVISED MAY 2013 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. 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. 3. Ri Inverting input resistance which sets the closed-loop gain in conjunction with RF. 4. RF External feedback resistance which sets the closed-loop gain in conjunction with Ri. Copyright © 2006–2013, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: LM4941 LM4941SDBD LM4941TMBD 5 LM4941, LM4941SDBD, LM4941TMBD SNAS347C – JUNE 2006 – REVISED MAY 2013 www.ti.com Typical Performance Characteristics Data taken with Bandwidth = 80kHz, AV = 1V/V and inputs are AC-coupled except where specified. THD+N vs Output Power VDD = 5V, RL = 8Ω, f = 1kHz 10 10 1 THD+N (%) THD+N (%) 1 0.1 0.01 0.1 0.01 0.001 10m 100m 1 0.001 10m 2 OUTPUT POWER (W) 10 100m Figure 4. Figure 5. THD+N vs Frequency VDD = 5V, RL = 8Ω, PO = 700mW THD+N vs Frequency VDD = 3V, RL = 8Ω, PO = 250mW 10 THD+N (%) 0.01 0.1 0.01 0.001 20 100 1k 0.001 20 10k 20k 100 FREQUENCY (Hz) 10k 20k Figure 7. PSRR vs Frequency VDD = 5V, RL = 8Ω, Inputs terminated 0 -10 -10 -20 -20 -30 -30 -40 -40 PSRR (dB) PSRR (dB) 1k FREQUENCY (Hz) Figure 6. -50 -60 -70 PSRR vs Frequency VDD = 3V, RL = 8Ω, Inputs terminated -50 -60 -70 -80 -80 -90 -90 -100 -100 -110 -110 -120 20 -120 20 100 1k FREQUENCY (Hz) 10k 20k 100 1k Submit Documentation Feedback 10k 20k FREQUENCY (Hz) Figure 8. 6 2 1 0.1 0 1 OUTPUT POWER (W) 1 THD+N (%) THD+N vs Output Power VDD = 3V, RL = 8Ω, f = 1kHz Figure 9. Copyright © 2006–2013, Texas Instruments Incorporated Product Folder Links: LM4941 LM4941SDBD LM4941TMBD LM4941, LM4941SDBD, LM4941TMBD www.ti.com SNAS347C – JUNE 2006 – REVISED MAY 2013 Typical Performance Characteristics (continued) Data taken with Bandwidth = 80kHz, AV = 1V/V and inputs are AC-coupled except where specified. CMRR vs Frequency VDD = 5V, RL = 8Ω -40 -50 -50 -60 -60 CMRR (dB) CMRR (dB) -40 -70 -70 -80 -80 -90 -90 -100 20 100 CMRR vs Frequency VDD = 3V, RL = 8Ω -100 20 10k 20k 1k 100 FREQUENCY (Hz) Figure 10. Figure 11. PSRR vs Common Mode Voltage VDD = 5V, RL = 8Ω, f = 217Hz PSRR vs Common Mode Voltage VDD = 3V, RL = 8Ω, f = 217Hz 0 -10 -10 -20 -20 -30 -30 PSRR (dB) PSRR (dB) 0 -40 -50 -60 -40 -50 -60 -70 -70 -80 -80 -90 -90 -100 -100 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 0 5 1.5 2 2.5 3 Figure 13. Power Dissipation vs Output Power VDD = 5V, RL = 8Ω Power Dissipation vs Output Power VDD = 3V, RL = 8Ω 300 POWER DISSIPATION (mW) POWER DISSIPATION (mW) 1 Figure 12. 600 500 400 300 200 100 0 0.5 DC COMMON MODE VOLTAGE (V) DC COMMON MODE VOLTAGE (V) 700 10k 20k 1k FREQUENCY (Hz) 0 200 400 600 800 1000 1200 1400 OUTPUT POWER (mW) 250 200 150 100 50 0 0 100 200 400 500 OUTPUT POWER (mW) Figure 14. Copyright © 2006–2013, Texas Instruments Incorporated 300 Figure 15. Submit Documentation Feedback Product Folder Links: LM4941 LM4941SDBD LM4941TMBD 7 LM4941, LM4941SDBD, LM4941TMBD SNAS347C – JUNE 2006 – REVISED MAY 2013 www.ti.com Typical Performance Characteristics (continued) Data taken with Bandwidth = 80kHz, AV = 1V/V and inputs are AC-coupled except where specified. Output Power vs Supply Voltage RL = 8Ω, Top-THD+N = 10%; Bot-THD+N = 1% Clipping Voltage vs Supply Voltage 0.5 2 1.8 0.4 DROPOUT VOLTAGE (V) OUTPUT POWER (W) 1.6 1.4 1.2 1 0.8 0.6 0.3 0.2 0.1 0.4 0.2 0 0 2 2 2.5 3 3.5 4 4.5 5 5.5 2.5 3 6 3.5 4 4.5 5 5.5 6 5 5.5 SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V) Figure 16. Figure 17. Output Power vs Load Resistance Top-VDD = 5V, 10% THD+N, Topmid-VDD = 5V, 1% THD+N Bot-VDD = 3V, 10% THD+N, Botmid-VDD = 3V, 1% THD+N IDDQ vs Supply Voltage 1.8 1.6 1.6 1.4 1.4 1.2 1.2 IDDQ (mA) OUTPUT POWER (W) 1.8 1 0.8 1 0.8 0.6 0.6 0.4 0.4 0.2 0.2 0 0 0 10 20 30 40 50 60 1 70 1.5 LOAD RESISTANCE (:) 2 1.5 3 3.5 4 4.5 SUPPLY VOLTAGE (V) Figure 18. Figure 19. Power Derating Curve fIN = 1kHz, RL = 8Ω TOTAL POWER DISSIPATION (W) 0.7 Note 11 0.6 0.5 LLP 0.4 TM 0.3 0.2 0.1 0 0 30 60 90 120 150 180 AMBIENT TEMPRATURE (oC) Figure 20. 8 Submit Documentation Feedback Copyright © 2006–2013, Texas Instruments Incorporated Product Folder Links: LM4941 LM4941SDBD LM4941TMBD LM4941, LM4941SDBD, LM4941TMBD www.ti.com SNAS347C – JUNE 2006 – REVISED MAY 2013 APPLICATION INFORMATION OPTIMIZING RF IMMUNITY The internal circuitry of the LM4941 suppresses the amount of RF signal that is coupled into the chip. However, certain external factors, such as output trace length, output trace orientation, distance between the chip and the antenna, antenna strength, speaker type, and type of RF signal, may affect the RF immunity of the LM4941. In general, the RF immunity of the LM4941 is application specific. Nevertheless, optimal RF immunity can be achieved by using short output traces and increasing the distance between the LM4941 and the antenna. DIFFERENTIAL AMPLIFIER EXPLANATION The LM4941 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 value remains VDD / 2. When setting the differential gain, the amplifier can be considered to have "halves". Each half uses an input and feedback resistor (Ri and RF) to set its respective closed-loop gain (see Figure 1). With Ri1 = Ri2 and RF1 = RF2, the gain is set at -RF / Ri for each half. This results in a differential gain of AVD = -RF/Ri (1) It is extremely important to match the input resistors to each other, as well as the feedback resistors to each other for best amplifier performance. See the Proper Selection of External Components section for more information. A differential amplifier works in a manner where the difference between the two input signals is amplified. In most applications, input signals will be 180° out of phase with each other. The LM4941 can be used, however, as a single-ended input amplifier while still retaining its fully differential benefits because it simply amplifies the difference between the inputs. All of these applications provide what is known as a "bridged mode" output (bridge-tied-load, BTL). This results in output signals that are 180° out of phase with respect to each other. Bridged mode operation is different from the single-ended amplifier configuration that connects the load between the amplifier output and ground. A bridged amplifier design has distinct advantages over the single-ended configuration: it provides differential drive to the load, thus doubling maximum possible output swing for a specific supply voltage. Four times the output power is possible compared with a single-ended amplifier under the same conditions. This increase in attainable output power assumes that the amplifier is not current limited or clipped. Choose an amplifier's closed-loop gain without causing excess clipping. A bridged configuration, such as the one used in the LM4941, also creates a second advantage over singleended amplifiers. Since the differential outputs are biased at half-supply, no net DC voltage exists across the load. This assumes that the input resistor pair and the feedback resistor pair are properly matched (see Proper Selection of External Components). BTL configuration eliminates the output coupling capacitor required in singlesupply, single-ended amplifier configurations. If an output coupling capacitor is not used in a single-ended output configuration, the half-supply bias across the load would result in both increased internal IC power dissipation as well as permanent loudspeaker damage. Further advantages of bridged mode operation specific to fully differential amplifiers like the LM4941 include increased power supply rejection ratio, common-mode noise reduction, and click and pop reduction. POWER DISSIPATION Power dissipation is a major concern when designing a successful amplifier, whether the amplifier is bridged or single-ended. Equation 2 states the maximum power dissipation point for a single-ended amplifier operating at a given supply voltage and driving a specified output load. PDMAX = (VDD)2 / (2π2RL) Single-Ended (2) However, a direct consequence of the increased power delivered to the load by a bridge amplifier is an increase in internal power dissipation versus a single-ended amplifier operating at the same conditions. PDMAX = 4 * (VDD)2 / (2π2RL) Bridge Mode Copyright © 2006–2013, Texas Instruments Incorporated (3) Submit Documentation Feedback Product Folder Links: LM4941 LM4941SDBD LM4941TMBD 9 LM4941, LM4941SDBD, LM4941TMBD SNAS347C – JUNE 2006 – REVISED MAY 2013 www.ti.com Since the LM4941 has bridged outputs, the maximum internal power dissipation is four times that of a singleended amplifier. Even with this substantial increase in power dissipation, the LM4941 does not require additional heatsinking under most operating conditions and output loading. From Equation 3, assuming a 5V power supply and an 8Ω load, the maximum power dissipation point is 625mW. The maximum power dissipation point obtained from Equation 3 must not be greater than the power dissipation results from Equation 4: PDMAX = (TJMAX - TA) / θJA (4) The LM4941's θJA in a DSBGA package is 100°C/W. Depending on the ambient temperature, TA, of the system surroundings, Equation 4 can be used to find the maximum internal power dissipation supported by the IC packaging. If the result of Equation 3 is greater than that of Equation 4, then either the supply voltage must be decreased, the load impedance increased, the ambient temperature reduced, or the θJA reduced with heatsinking. In many cases, larger traces near the output, VDD, and GND pins can be used to lower the θJA. The larger areas of copper provide a form of heatsinking allowing higher power dissipation. For the typical application of a 5V power supply, with an 8Ω load, the maximum ambient temperature possible without violating the maximum junction temperature is approximately 87.5°C provided that device operation is around the maximum power dissipation point. Recall that internal power dissipation is a function of output power. If typical operation is not around the maximum power dissipation point, the LM4941 can operate at higher ambient temperatures. Refer to the Typical Performance Characteristics curves for power dissipation information. 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 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 and 0.1µF bypass capacitors that increase supply stability. This, however, does not eliminate the need for bypassing the supply nodes of the LM4941. The LM4941 will operate without the bypass capacitor CB, although the PSRR may decrease. A 1µF capacitor is recommended for CB. This value maximizes PSRR performance. Lesser values may be used, but PSRR decreases at frequencies below 1kHz. The issue of CB selection is thus dependant upon desired PSRR and click and pop performance as explained in the section Proper Selection of External Components. SHUTDOWN FUNCTION In order to reduce power consumption while not in use, the LM4941 contains shutdown circuitry that is used to turn off the amplifier's bias circuitry. The device may then be placed into shutdown mode by toggling the SHDN pin to logic low. It is best to switch between ground and supply for maximum performance. While the device may be disabled with shutdown voltages in between ground and supply, the idle current may be greater than the typical value of 0.1µA. In either case, the SHDN pin should be tied to a definite voltage to avoid unwanted state changes. In many applications, a microcontroller or microprocessor output is used to control the shutdown circuitry, which provides a quick, smooth transition to shutdown. Another solution is to use a single-throw switch in conjunction with an external pull-up resistor. This scheme ensures that the shutdown pin will not float, thus preventing unwanted state changes. PROPER SELECTION OF EXTERNAL COMPONENTS Proper selection of external components in applications using integrated power amplifiers is critical when optimizing device and system performance. Although the LM4941 is tolerant to a variety of external component combinations, consideration of component values must be made when maximizing overall system quality. The LM4941 is unity-gain stable, giving the designer maximum system flexibility. The LM4941 should be used in low closed-loop gain configurations to minimize THD+N values and maximize signal to noise ratio. Low gain configurations require large input signals to obtain a given output power. Input signals equal to or greater than 1VRMS are available from sources such as audio codecs. When used in its typical application as a fully differential power amplifier the LM4941 does not require input coupling capacitors for input sources with DC common-mode voltages of less than VDD. Exact allowable input common-mode voltage levels are actually a function of VDD, Ri, and RF and may be determined by Equation 5: VCMi < (VDD-1.2)(Ri+RF)/RF-VDD/2(Ri/ RF) -RF / Ri = AVD 10 Submit Documentation Feedback (5) (6) Copyright © 2006–2013, Texas Instruments Incorporated Product Folder Links: LM4941 LM4941SDBD LM4941TMBD LM4941, LM4941SDBD, LM4941TMBD www.ti.com SNAS347C – JUNE 2006 – REVISED MAY 2013 When using DC coupled inputs, special care must be taken to match the values of the input resistors (Ri1 and Ri2) to each other. Because of the balanced nature of differential amplifiers, resistor matching differences can result in net DC currents across the load. This DC current can increase power consumption, internal IC power dissipation, reduce PSRR, and possibly damaging the loudspeaker. The chart below demonstrates this problem by showing the effects of differing values between the feedback resistors while assuming that the input resistors are perfectly matched. The results below apply to the application circuit shown in Figure 1, and assumes that VDD = 5V, RL = 8Ω, and the system has DC coupled inputs tied to ground. Tolerance Ri1 Ri2 V01–V02 ILOAD 20% 0.8R 1.2R –0.500V 62.5mA 10% 0.9R 1.1R –0.250V 31.25mA 5% 0.95R 1.05R –0.125V 15.63mA 1% 0.99R 1.01R –0.025V 3.125mA 0% R R 0 0 Since the same variations can have a significant effect on PSRR and CMRR performance, it is highly recommended that the input resistors be matched to 1% tolerance or better for best performance. Recommended TM Board Layout Figure 21. Recommended TM Board Layout: Top Layer Copyright © 2006–2013, Texas Instruments Incorporated Figure 22. Recommended TM Board Layout: Top Overlay Submit Documentation Feedback Product Folder Links: LM4941 LM4941SDBD LM4941TMBD 11 LM4941, LM4941SDBD, LM4941TMBD SNAS347C – JUNE 2006 – REVISED MAY 2013 www.ti.com Figure 23. Recommended TM Board Layout: Bottom Layer Recommended WSON Board Layout Figure 24. Recommended WSON Board Layout: Top Layer 12 Submit Documentation Feedback Figure 25. Recommended WSON Board Layout: Top Overlay Copyright © 2006–2013, Texas Instruments Incorporated Product Folder Links: LM4941 LM4941SDBD LM4941TMBD LM4941, LM4941SDBD, LM4941TMBD www.ti.com SNAS347C – JUNE 2006 – REVISED MAY 2013 Figure 26. Recommended WSON Board Layout: Bottom Layer LM4941 Reference Design Boards Bill Of Materials Designator Value Tolerance Part Description Ri1, Ri2 20kΩ 0.10% 1/10W, 0.1% 0805 Resistor Rf1, Rf2 20kΩ 0.10% 1/10W, 0.1% 0805 Resistor Ci1, Ci2 0Ω Cb, Cs 1μF Comments 1/10W, 0.1% 0805 Resistor 10% In, Out, VDD, J1 16V Tantalum 1210 Capacitor 0.100” 1x2 header, Vertical mount Copyright © 2006–2013, Texas Instruments Incorporated Input, Output, VDD/GND, Shutdown Control Submit Documentation Feedback Product Folder Links: LM4941 LM4941SDBD LM4941TMBD 13 LM4941, LM4941SDBD, LM4941TMBD SNAS347C – JUNE 2006 – REVISED MAY 2013 www.ti.com REVISION HISTORY 14 Rev Date Description 1.0 06/28/06 Initial release. 1.1 07/10/06 Added the WSON pkg mktg outline (per Kashif J.) 1.2 08/04/06 Added the WSON package and marking diagrams. 1.3 10/12/06 Edited some of the Typical Performance curves' labels and some text edits. 1.4 10/25/06 Added the WSON boards. 1.5 11/07/06 Text edits. 1.6 11/15/06 Replaced curve 20170381 with 20170382 and input text edits. 1.7 03/09/07 Changed the Limit value from 70 to 80 on the PSRR in the EC 5V EC table. C 05/03/13 Changed layout of National Data Sheet to TI format. Submit Documentation Feedback Copyright © 2006–2013, Texas Instruments Incorporated Product Folder Links: LM4941 LM4941SDBD LM4941TMBD 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) LM4941SD/NOPB ACTIVE WSON NGS 8 1000 RoHS & Green SN Level-1-260C-UNLIM 4941 LM4941SDX/NOPB ACTIVE WSON NGS 8 4500 RoHS & Green SN Level-1-260C-UNLIM 4941 LM4941TM/NOPB ACTIVE DSBGA YFQ 9 250 RoHS & Green SNAGCU Level-1-260C-UNLIM -40 to 85 G H6 LM4941TMX/NOPB ACTIVE DSBGA YFQ 9 3000 RoHS & Green SNAGCU Level-1-260C-UNLIM -40 to 85 G H6 (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