LM4861MX

LM4861 www.ti.com SNAS095C – MAY 1997 – REVISED MAY 2013 LM4861 1.1W Audio Power Amplifier with Shutdown Mode Check for Samples: LM4861 FEATURES DESCRIPTION • The LM4861 is a bridge-connected audio power amplifier capable of delivering 1.1W of continuous average power to an 8Ω load with 1% THD+N using a 5V power supply. 1 2 • • • • • No output coupling capacitors, bootstrap capacitors, or snubber circuits are necessary Small Outline (SOIC) packaging Compatible with PC power supplies Thermal shutdown protection circuitry Unity-gain stable External gain configuration capability APPLICATIONS • • • • Personal computers Portable consumer products Self-powered speakers Toys and games The LM4861 features an externally controlled, lowpower consumption shutdown mode, as well as an internal thermal shutdown protection mechanism. KEY SPECIFICATIONS • • • Boomer audio power amplifiers were designed specifically to provide high quality output power with a minimal amount of external components using surface mount packaging. Since the LM4861 does not require output coupling capacitors, bootstrap capacitors, or snubber networks, it is optimally suited for low-power portable systems. THD+N for 1kHz at 1W continuous average output power into 8Ω 1.0% (max) Output power at 10% THD+N at 1kHz into 8Ω 1.5 W (typ) Shutdown Current 0.6µA (typ) The unity-gain stable LM4861 can be configured by external gain-setting resistors for differential gains of up to 10 without the use of external compensation components. Higher gains may be achieved with suitable compensation. Connection Diagram Figure 1. 8-Lead SOIC - Top View See D Package 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 © 1997–2013, Texas Instruments Incorporated LM4861 SNAS095C – MAY 1997 – REVISED MAY 2013 www.ti.com Typical Application Figure 2. Typical Audio Amplifier Application Circuit 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 © 1997–2013, Texas Instruments Incorporated Product Folder Links: LM4861 LM4861 www.ti.com SNAS095C – MAY 1997 – REVISED MAY 2013 Absolute Maximum Ratings (1) (2) Supply Voltage 6.0V −65°C to +150°C Storage Temperature −0.3V to VDD + 0.3V Input Voltage Power Dissipation (3) Internally limited ESD Susceptibility (4) 3000V ESD Susceptibility (5) 250V Junction Temperature 150°C Soldering Information (1) (2) (3) (4) (5) SOIC Package Vapor Phase (60 sec.) 215°C Infrared (15 sec.) 220°C 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. 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 the Absolute Maximum Ratings, whichever is lower. For the LM4861, TJMAX = 150°C, and the typical junction-to-ambient thermal resistance, when board mounted, is 140°C/W. Human body model, 100pF discharged through a 1.5kΩ resistor. Machine Model, 220pF–240pF discharged through all pins. Operating Ratings TMIN ≤ TA ≤ TMAX Temperature Range −40°C ≤ TA ≤ +85°C 2.0V ≤ VDD ≤ 5.5V Supply Voltage Thermal Resistance Electrical Characteristics θJC (typ)—M08A 35°C/W θJA (typ)—M08A 140°C/W θJC (typ)—N08E 37°C/W θJA (typ)—N08E 107°C/W (1) (2) The following specifications apply for VDD = 5V, unless otherwise specified. Limits apply for TA = 25°C. Symbol VDD Parameter Conditions LM4861 Typical Supply Voltage (5) (3) Limit (4) Units (Limits) 2.0 V (min) 5.5 V (max) 6.5 10.0 mA (max) IDD Quiescent Power Supply Current VIN = 0V, IO = 0A ISD Shutdown Current VSHUTDOWN = VDD 0.6 10.0 μA (max) VOS Output Offset Voltage VIN = 0V 5.0 50.0 mV (max) PO Output Power THD = 1% (max); f = 1 kHz 1.1 1.0 W (min) THD+N Total Harmonic Distortion + Noise PO = 1Wrms; 20 Hz ≤ f ≤ 20 kHz 0.72 % PSRR Power Supply Rejection Ratio VDD = 4.9V to 5.1V 65 dB (1) (2) (3) (4) (5) 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). The quiescent power supply current depends on the offset voltage when a practical load is connected to the amplifier. Submit Documentation Feedback Copyright © 1997–2013, Texas Instruments Incorporated Product Folder Links: LM4861 3 LM4861 SNAS095C – MAY 1997 – REVISED MAY 2013 www.ti.com High Gain Application Circuit Figure 3. Audio Ampiifier with AVD = 20 Single Ended Application Circuit *CS and CB size depend on specific application requirements and constraints. Typical vaiues of CS and CB are 0.1 μF. **Pin 1 should be connected to VDD to disable the amplifier or to GND to enable the amplifier. This pin should not be left floating. ***These components create a “dummy” load for pin 8 for stability purposes. Figure 4. Single-Ended Amplifier with AV = −1 4 Submit Documentation Feedback Copyright © 1997–2013, Texas Instruments Incorporated Product Folder Links: LM4861 LM4861 www.ti.com SNAS095C – MAY 1997 – REVISED MAY 2013 External Components Description (Figure 2 and Figure 3) Components 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 Ri Ci). 2. Ci Input coupling capacitor which blocks DC voltage at the amplifier's input terminals. Also creates a high pass filter with Ri at fC = 1 / (2π Ri Ci). 3. Rf Feedback resistance which sets closed-loop gain in conjunction with Ri. 4. CSApplication Information Supply bypass capacitor which provides power supply filtering. Refer to for proper placement and selection of supply bypass capacitor. 5. CB Bypass pin capacitor which provides half supply filtering. Refer to Application Information for proper placement and selection of bypass capacitor. 6. Cf (1) Cf in conjunction with Rf creates a low-pass filter which bandwidth limits the amplifier and prevents possible high frequency oscillation bursts. fC = 1 / (2π Rf Cf) (1) Optional component dependent upon specific design requirements. Refer to Application Information for more information. Submit Documentation Feedback Copyright © 1997–2013, Texas Instruments Incorporated Product Folder Links: LM4861 5 LM4861 SNAS095C – MAY 1997 – REVISED MAY 2013 www.ti.com Typical Performance Characteristics 6 THD+N vs Frequency THD+N vs Frequency Figure 5. Figure 6. THD+N vs Frequency THD+N vs Output Power Figure 7. Figure 8. THD+N vs Output Power Output Power vs Load Resistance Figure 9. Figure 10. Submit Documentation Feedback Copyright © 1997–2013, Texas Instruments Incorporated Product Folder Links: LM4861 LM4861 www.ti.com SNAS095C – MAY 1997 – REVISED MAY 2013 Typical Performance Characteristics (continued) Output Power vs Supply Voltage Power Dissipation vs Output Power Figure 11. Figure 12. Noise Floor vs Frequency Supply Current Distribution vs Temperature Figure 13. Figure 14. Supply Current vs Supply Voltage Power Derating Curve Figure 15. Figure 16. Submit Documentation Feedback Copyright © 1997–2013, Texas Instruments Incorporated Product Folder Links: LM4861 7 LM4861 SNAS095C – MAY 1997 – REVISED MAY 2013 www.ti.com Typical Performance Characteristics (continued) 8 Power Supply Rejection Ratio Open Loop Frequency Response Figure 17. Figure 18. Submit Documentation Feedback Copyright © 1997–2013, Texas Instruments Incorporated Product Folder Links: LM4861 LM4861 www.ti.com SNAS095C – MAY 1997 – REVISED MAY 2013 APPLICATION INFORMATION BRIDGE CONFIGURATION EXPLANATION As shown in Figure 2 , the LM4861 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 40kΩ resistors. Figure 2 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 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 its 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. Consequently, 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 closed-loop gain without causing excessive clipping which will damage high frequency transducers used in loudspeaker systems, please refer to AUDIO POWER AMPLIFIER DESIGN. A bridge configuration, such as the one used in Boomer Audio Power Amplifiers, 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, single-ended amplifier configuration. Without an output coupling capacitor in a single supply, single-ended amplifier, the half-supply bias across the load would result in both increased internal IC power dissipation and also permanent loudspeaker damage. An output coupling capacitor forms a high pass filter with the load requiring that a large value such as 470μF be used with an 8Ω load to preserve low frequency response. This combination does not produce a flat response down to 20Hz, but does offer a compromise between printed circuit board size and system cost, versus low frequency response. 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. Equation 3 states the maximum power dissipation point for a bridge amplifier operating at a given supply voltage and driving a specified output load. PDMAX = 4*(VDD)2 / (2π2RL) (2) Since the LM4861 has two operational amplifiers in one package, the maximum internal power dissipation is 4 times that of a single-ended amplifier. Even with this substantial increase in power dissipation, the LM4861 does not require heatsinking. 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 that results from Equation 3: PDMAX = (TJMAX − TA) / θJA (3) For the LM4861 surface mount package, θJA = 140°C/W and TJMAX = 150°C. Depending on the ambient temperature, TA, of the system surroundings, Equation 3 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 3, then either the supply voltage must be decreased or the load impedance increased. 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 62.5°C provided that device operation is around the maximum power dissipation point. Power dissipation is a function of output power and thus, if typical operation is not around the maximum power dissipation point, the ambient temperature can be increased. Refer to the Typical Performance Characteristics curves for power dissipation information for lower output powers. Submit Documentation Feedback Copyright © 1997–2013, Texas Instruments Incorporated Product Folder Links: LM4861 9 LM4861 SNAS095C – MAY 1997 – REVISED MAY 2013 www.ti.com POWER SUPPLY BYPASSING As with any power 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. As displayed in the Typical Performance Characteristics, the effect of a larger half supply bypass capacitor is improved low frequency THD+N due to increased half-supply stability. Typical applications employ a 5V regulator with 10μF and a 0.1μF bypass capacitors which aid in supply stability, but do not eliminate the need for bypassing the supply nodes of the LM4861. The selection of bypass capacitors, especially CB, is thus dependant upon desired low frequency THD+N, system cost, and size constraints. SHUTDOWN FUNCTION In order to reduce power consumption while not in use, the LM4861 contains a shutdown pin to externally turn off the amplifier's bias circuitry. The shutdown feature turns the amplifier off when a logic high is placed on the shutdown pin. Upon going into shutdown, the output is immediately disconnected from the speaker. A typical quiescent current of 0.6μA results when the supply voltage is applied to the shutdown pin. In many applications, a microcontroller or microprocessor output is used to control the shutdown circuitry which provides a quick, smooth transition into shutdown. Another solution is to use a single-pole, single-throw switch that when closed, is connected to ground and enables the amplifier. If the switch is open, then a soft pull-up resistor of 47kΩ will disable the LM4861. There are no soft pull-down resistors inside the LM4861, so a definite shutdown pin voltage must be applied externally, or the internal logic gate will be left floating which could disable the amplifier unexpectedly. HIGHER GAIN AUDIO AMPLIFIER The LM4861 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 may be needed, as shown in Figure 3, 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 = 100kΩ and Cf = 5pF. These components result in a −3dB point of approximately 320kHz. Once the differential gain of the amplifier has been calculated, a choice of Rf will result, and Cf can then be calculated from the formula stated in External Components Description . VOICE-BAND AUDIO AMPLIFIER Many applications, such as telephony, only require a voice-band frequency response. Such an application usually requires a flat frequency response from 300Hz to 3.5kHz. By adjusting the component values of Figure 3, this common application requirement can be implemented. The combination of Ri and Ci form a highpass filter while Rf and Cf form a lowpass filter. Using the typical voice-band frequency range, with a passband differential gain of approximately 100, the following values of Ri, Ci, Rf, and Cf follow from the equations stated in External Components Description . Ri = 10kΩ, Rf = 510k ,Ci = 0.22μF, and Cf = 15pF (4) Five times away from a −3dB point is 0.17dB down from the flatband response. With this selection of components, the resulting −3dB points, fL and fH, are 72Hz and 20kHz, respectively, resulting in a flatband frequency response of better than ±0.25dB with a rolloff of 6dB/octave outside of the passband. If a steeper rolloff is required, other common bandpass filtering techniques can be used to achieve higher order filters. SINGLE-ENDED AUDIO AMPLIFIER Although the typical application for the LM4861 is a bridged monoaural amp, it can also be used to drive a load single-endedly in applications, such as PC cards, which require that one side of the load is tied to ground. Figure 4 shows a common single-ended application, where VO1 is used to drive the speaker. This output is coupled through a 470μF capacitor, which blocks the half-supply DC bias that exists in all single-supply amplifier configurations. This capacitor, designated CO in Figure 4, in conjunction with RL, forms a highpass filter. The −3dB point of this high pass filter is 1/(2πRLCO), so care should be taken to make sure that the product of RL and CO is large enough to pass low frequencies to the load. When driving an 8Ω load, and if a full audio spectrum reproduction is required, CO should be at least 470μF. VO2, the output that is not used, is connected through a 0.1 μF capacitor to a 2kΩ load to prevent instability. While such an instability will not affect the waveform of VO1, it is good design practice to load the second output. 10 Submit Documentation Feedback Copyright © 1997–2013, Texas Instruments Incorporated Product Folder Links: LM4861 LM4861 www.ti.com SNAS095C – MAY 1997 – REVISED MAY 2013 AUDIO POWER AMPLIFIER DESIGN Design a 1W / 8Ω Audio Amplifier Given: Power Output 1 Wrms Load Impedance 8Ω Input Level 1 Vrms Input Impedance 20 kΩ Bandwidth 100 Hz–20 kHz ± 0.25 dB A designer must first determine the needed supply rail to obtain the specified output power. By extrapolating from Figure 11 in Typical Performance Characteristics, the supply rail can be easily found. A second way to determine the minimum supply rail is to calculate the required Vopeak using Equation 5 and add the dropout voltage. Using this method, the minimum supply voltage would be (Vopeak + VOD , where VOD is typically 0.6V. (5) For 1W of output power into an 8Ω load, the required Vopeak is 4.0V. A minumum supply rail of 4.6V results from adding Vopeak and Vod. But 4.6V is not a standard voltage that exists in many applications and for this reason, a supply rail of 5V is designated. Extra supply voltage creates dynamic headroom that allows the LM4861 to reproduce peaks in excess of 1Wwithout clipping the signal. 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. Once the power dissipation equations have been addressed, the required differential gain can be determined from Equation 6. (6) (7) Rf/Ri = AVD / 2 From Equation 6, the minimum Avd is 2.83: Avd = 3 Since the desired input impedance was 20kΩ, and with a Avd of 3, a ratio of 1:1.5 of Rf to Ri results in an allocation of Ri = 20kΩ, Rf = 30kΩ. The final design step is to address the bandwidth requirements which must be stated as a pair of −3dB frequency points. Five times away from a −3db point is 0.17dB down from passband response which is better than the required ±0.25dB specified. This fact results in a low and high frequency pole of 20Hz and 100kHz respectively. As stated in External Components Description , Ri in conjunction with Ci create a highpass filter. Ci ≥ 1 / (2π*20kΩ*20Hz) = 0.397μF; use 0.39μF. (8) The high frequency pole is determined by the product of the desired high frequency pole, fH, and the differential gain, Avd. With a Avd = 2 and fH = 100kHz, the resulting GBWP = 100kHz which is much smaller than the LM4861 GBWP of 4MHz. This figure displays that if a designer has a need to design an amplifier with a higher differential gain, the LM4861 can still be used without running into bandwidth problems. Submit Documentation Feedback Copyright © 1997–2013, Texas Instruments Incorporated Product Folder Links: LM4861 11 LM4861 SNAS095C – MAY 1997 – REVISED MAY 2013 www.ti.com LM4861 MDA MWA 1.1W Audio Power Amplifier with Shutdown Mode Figure 19. Die Layout (B - Step) Table 1. DIE/WAFER CHARACTERISTICS Fabrication Attributes Physical Die Identification Die Step General Die Information LM4861B Bond Pad Opening Size (min) 83µm x 83µm B Bond Pad Metalization ALUMINUM Passivation VOM NITRIDE Physical Attributes Wafer Diameter 150mm Back Side Metal BARE BACK Dise Size (Drawn) 1372µm x 2032µm 54.0mils x 80.0mils Back Side Connection GND Thickness 406µm Nominal Min Pitch 108µm Nominal Special Assembly Requirements: Note: Actual die size is rounded to the nearest micron. Die Bond Pad Coordinate Locations (B - Step) (Referenced to die center, coordinates in µm) NC = No Connection, N.U. = Not Used SIGNAL NAME PAD# NUMBER X/Y COORDINATES PAD SIZE X Y X Y SHUTDOWN 1 -425 710 83 x BYPASS 2 -445 499 83 x 83 NC 3 -445 -34 83 x 170 NC 4 -445 -383 83 x 83 INPUT + 5 -445 -492 83 x 83 12 Submit Documentation Feedback 83 Copyright © 1997–2013, Texas Instruments Incorporated Product Folder Links: LM4861 LM4861 www.ti.com SNAS095C – MAY 1997 – REVISED MAY 2013 INPUT - 6 -352 -710 83 x 83 GND 7 -243 -710 83 x 83 Vo1 8 -91 -710 170 x 83 GND 9 445 -574 83 x 170 VDD 10 445 -2 83 x 170 NC 11 445 387 83 x 83 GND 12 445 633 83 x 170 Vo2 13 -63 710 170 x 83 GND 14 -215 710 83 x 83 Submit Documentation Feedback Copyright © 1997–2013, Texas Instruments Incorporated Product Folder Links: LM4861 13 LM4861 SNAS095C – MAY 1997 – REVISED MAY 2013 www.ti.com REVISION HISTORY Changes from Revision B (May 2013) to Revision C • 14 Page Changed layout of National Data Sheet to TI format .......................................................................................................... 13 Submit Documentation Feedback Copyright © 1997–2013, Texas Instruments Incorporated Product Folder Links: LM4861 PACKAGE OPTION ADDENDUM www.ti.com 7-Oct-2022 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) Samples (4/5) (6) LM4861M ACTIVE SOIC D 8 95 Non-RoHS & Green Call TI Level-1-235C-UNLIM -40 to 85 LM 4861M Samples LM4861M/NOPB ACTIVE SOIC D 8 95 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 LM 4861M Samples LM4861MX ACTIVE SOIC D 8 2500 Non-RoHS & Green Call TI Level-1-235C-UNLIM -40 to 85 LM 4861M Samples LM4861MX/NOPB ACTIVE SOIC D 8 2500 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 LM 4861M Samples (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