LDA08B

LM4900 NSC | Alldatasheet

Document overview

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Technical content

Features

n MSOP, LLP, and SOP packaging n No output coupling capacitors, bootstrap capacitors, or snubber circuits are necessary n Thermal shutdown protection circuitry n Unity-gain stable n External gain configuration capability n Latest generation ’click and pop’ suppression circuitry

Applications

n PDA’s n Any portable audio application Typical Application Boomer ® is a registered trademark of National Semiconductor Corporation. DS200064-1 FIGURE 1. Typical Audio Amplifier Application Circuit

Order Number LM4900MM, LM4900M See NS Package Number MUA08A, M08A DS200064-76 Top View Order Number LM4900LD See NS Package Number LDA08B LM4900 www.national.com 2

Absolute Maximum Ratings(Note 2) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage 6.0V Storage Temperature −65˚C to +150˚C Input Voltage −0.3V to V DD + 0.3V Power Dissipation (Note 3) Internally limited ESD Susceptibility (Note 4) 2000V ESD Susceptibility (Note 5) 200V Junction Temperature 150˚C Soldering Information Small Outline Package Vapor Phase (60 sec.) 215˚C Infrared (15 sec.) 220˚C See AN-450 “Surface Mounting and their Effects on Product Reliability” for other methods of soldering surface mount devices. Thermal Resistance θ JC (M08A) 35˚C/W θJA (M08A) 170˚C/W θJC (MUA08A) 56˚C/W θJA (MUA08A) 190˚C/W θJA (LDA08B) 67˚C/W Operating Ratings Temperature Range TMIN ≤ TA ≤ TMAX −40˚C ≤ TA ≤ +85˚C Supply Voltage 2.0V ≤ VDD ≤ 5.5V Electrical Characteristics(Note 1) (Note 2) The following specifications apply for VDD = 5V, for all available packages, unless otherwise specified. Limits apply for TA = 25˚C Symbol Parameter Conditions LM4900 Units (Limits)Typical (Note 6) Limit (Notes 7, IDD Quiescent Power Supply Current VIN = 0V, IO = 0A (Note 8) 4 6.0 mA (max) ISD Shutdown Current V PIN1 =V DD 0.1 5 µA (max) VOS Output Offset Voltage V IN = 0V 5 50 mV (max) PO Output Power THD = 1% (max); f = 1kHz; R L =8 Ω ; 675 300 mW (min) THD+N Total Harmonic Distortion+Noise P O = 400 mWrms; AVD =2 ;RL =8 Ω ; 20Hz ≤ f≤ 20kHz, BW < 80kHz 0.4 % PSRR Power Supply Rejection Ratio V RIPPLE = 200mV sine p-p dB f = 217Hz (Note 10) 70 f = 1KHz (Note 10) 67 f = 217Hz (Note 11) 55 f = 1KHz (Note 11) 55 Electrical Characteristics(Note 1) (Note 2) The following specifications apply for VDD = 3.3V, for all available packages, unless otherwise specified. Limits apply for TA = 25˚C Symbol Parameter Conditions LM4900 Units (Limits)Typical (Note 6) Limit (Notes 7, IDD Quiescent Power Supply Current VIN = 0V, IO = 0A (Note 8) 3 5 mA (max) ISD Shutdown Current V PIN1 =V DD 0.1 3 µA (max) VOS Output Offset Voltage V IN = 0V 5 50 mV (max) PO Output Power THD = 1% (max); f = 1kHz; R L =8 Ω ; 265 mW (min) THD+N Total Harmonic Distortion+Noise P O = 250 mWrms; AVD =2 ;RL =8 Ω ; 20Hz ≤ f≤ 20kHz, BW < 80kHz 0.4 % PSRR Power Supply Rejection Ratio V RIPPLE = 200mV sine p-p dB f = 217Hz (Note 10) 73 f = 1KHz (Note 10) 70 f = 217Hz (Note 11) 60 f = 1KHz (Note 11) 68 LM4900 www.national.com3

Electrical Characteristics(Note 1) (Note 2) The following specifications apply for VDD = 2.6V, for all available packages, unless otherwise specified. Limits apply for TA = 25˚C Symbol Parameter Conditions LM4900 Units (Limits)Typical (Note 6) Limit (Notes 7, IDD Quiescent Power Supply Current VIN = 0V, IO = 0A (Note 8) 2.6 4 mA (max) ISD Shutdown Current V PIN1 =V DD 0.1 2.0 µA (max) VOS Output Offset Voltage V IN =0 V 5 m V PO Output Power THD = 1% (max); f = 1kHz; R L =8 Ω 130 mW THD+N Total Harmonic Distortion+Noise P O = 100 mWrms; AVD =2 ;RL =8 Ω ; 20Hz ≤ f≤ 20kHz, BW < 80kHz 0.4 % PSRR Power Supply Rejection Ratio V RIPPLE = 200mV sine p-p dBf = 217Hz (Note 11) 58 f = 1KHz (Note 11) 63 Note 1:All voltages are measured with respect to the ground pin, unless otherwise specified. Note 2:Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which guarantee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit is given, however, the typical value is a good indication of device performance. Note 3:The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX ,θJA, and the ambient temperature TA. The maximum allowable power dissipation is PDMAX =( TJMAX −T A)/θJA or the number given in the Absolute Maximum Ratings, whichever is lower. For the LM4900, TJMAX = 150˚C. The typical junction-to-ambient thermal resistance, when board mounted, is 190˚C/W for package number MUA08A. Note 4:Human body model, 100pF discharged through a 1.5kΩ resistor. Note 5:Machine Model, 220pF–240pF discharged through all pins. Note 6:Typicals are measured at 25˚C and represent the parametric norm. Note 7:Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level). Note 8:The quiescent power supply current depends on the offset voltage when a practical load is connected to the amplifier. Note 9:Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis. Note 10:Unterminated input. Note 11:10Ω terminated input. LM4900 www.national.com 4

External Components Description(Figure 1) Components Functional Description 1. R i Inverting input resistance which sets the closed-loop gain in conjunction with RF. This resistor also forms a high pass filter with Ciat fc = 1/(2π R iC I). 2. C i Input coupling capacitor which blocks the DC voltage at the amplifier’s input terminals. Also creates a highpass filter with Riat fc = 1/(2π R iC i). Refer to the section,Proper Selection of External Components, for an explanation of how to determine the value of Ci. 3. R F Feedback resistance which sets the closed-loop gain in conjunction with Ri. 4. C S Supply bypass capacitor which provides power supply filtering. Refer to thePower Supply Bypassing section for information concerning proper placement and selection of the supply bypass capacitor. 5. C B Bypass pin capacitor which provides half-supply filtering. Refer to theProper Selection of External Components for information concerning proper placement and selection of CB. Typical Performance Characteristics THD+N vs Frequency DS200064-30 THD+N vs Frequency DS200064-31 THD+N vs Frequency DS200064-32 THD+N vs Frequency DS200064-33 LM4900 www.national.com5

Typical Performance Characteristics(Continued) THD+N vs Frequency DS200064-34 THD+N vs Frequency DS200064-35 THD+N vs Frequency DS200064-36 THD+N vs Frequency DS200064-37 THD+N vs Frequency DS200064-38 THD+N vs Frequency DS200064-39 LM4900 www.national.com 6

Typical Performance Characteristics(Continued) THD+N vs Frequency DS200064-40 THD+N vs Output Power DS200064-41 THD+N vs Output Power DS200064-42 THD+N vs Output Power DS200064-43 THD+N vs Output Power DS200064-44 THD+N vs Output Power DS200064-45 LM4900 www.national.com7

Typical Performance Characteristics(Continued) THD+N vs Output Power DS200064-46 THD+N vs Output Power DS200064-47 THD+N vs Output Power DS200064-48 THD+N vs Output Power DS200064-49 THD+N vs Output Power DS200064-50 THD+N vs Output Power DS200064-51 LM4900 www.national.com 8

Typical Performance Characteristics(Continued) Output Power vs Supply Voltage DS200064-52 Output Power vs Supply Voltage DS200064-53 Output Power vs Supply Voltage DS200064-54 Output Power vs Supply Voltage DS200064-55 Output Power vs Load Resistance DS200064-56 Power Dissipation vs Output Power DS200064-57 LM4900 www.national.com9

Typical Performance Characteristics(Continued) Power Dissipation vs Output Power DS200064-58 Power Dissipation vs Output Power DS200064-59 Clipping Voltage vs Supply Voltage DS200064-60 Noise Floor DS200064-61 Noise Floor DS200064-62 Frequency Response vs Input Capacitor Size DS200064-71 LM4900 www.national.com 10

Typical Performance Characteristics(Continued) Power Supply Rejection Ratio DS200064-63 Power Supply Rejection Ratio DS200064-64 Power Supply Rejection Ratio DS200064-65 Power Supply Rejection Ratio DS200064-66 Power Supply Rejection Ratio vs Supply Voltage DS200064-67 Power Supply Rejection Ratio vs Supply Voltage DS200064-68 LM4900 www.national.com11

Typical Performance Characteristics(Continued) Note 12:This curve shows the LM4900LD’s thermal dissipation ability at different ambient temperatures given the exposed-DAP of the part is soldered to a plane of 1oz. Cu with an area given in the label of each curve. Supply Current vs Shutdown Voltage DS200064-69 LM4900MM Power Derating Curve DS200064-73 Supply Current vs Supply Voltage DS200064-70 LM4900LD Power Derating Curve(Note 12) DS200064-75 Open Loop Frequency Response DS200064-72 LM4900 www.national.com 12

Application Information

EXPOSED-DAP PACKAGE PCB MOUNTING CONSIDERATION The LM4900’s exposed-DAP (die-attach paddle) package (LD) provides a low thermal resistance between the die and the PCB to which the part is mounted and soldered. This allows rapid heat from the die to the surrounding PCB cop- per traces, ground plane, and surrounding air. This allows the LM4900LD to operate at higher output power levels in higher ambient temperatures than the MM package. Failing to optimize thermal design may compromise the high power performance and activate unwanted, though necessary, thermal shutdown protection. The LD package must have its DAP soldered to a copper pad on the PCB. The DAP’s PCB copper pad is connected to a large plane of continuous unbroken copper. This plane forms a thermal mass, heat sink, and radiation area. Place the heat sink area on either outside plane in the case of a two-sided PCB, or on an inner layer of a board with more than two layers. Connect the DAP copper pad to the inner layer or backside copper heat sink area with 2 vias. The via diameter should be 0.012in - 0.013in with a 1.27mm pitch. Ensure efficient thermal conductivity by plating through the vias. Best thermal performance is achieved with the largest prac- tical heat sink area. The power derating curve in theTypical Performance Characteristicsshows the maximum power dissipation versus temperature for several different areas of heat sink area. Placing the majority of the heat sink area on another plane is preferred as heat is best dissipated through the bottom of the chip. Further detailed and specific informa- tion concerning PCB layout, fabrication, and mounting an LD (LLP) package is available from National Semiconductor’s BRIDGE CONFIGURATION EXPLANATION As shown in Figure 1, the LM4900 has two operational amplifiers internally, allowing for a few different amplifier configurations. The first amplifier’s gain is externally config- urable, 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 R F to Riwhile the second amplifier’s gain is fixed by the two internal 10 kΩ resistors.Figure 1shows 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 A VD =2 *(RF/Ri) 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. Four times the output power is possible as compared to a single-ended amplifier under the same con- ditions. 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 ex- cessive clipping, please refer to theAudio Power Amplifier Design section. A bridge configuration, such as the one used in LM4900, also creates a second advantage over single-ended amplifi- ers. Since the differential outputs, V o1 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 configura- tion. If an output coupling capacitor is not used in a single-ended configuration, the half-supply bias across the load would result in both increased internal lC power dissi- pation as well as permanent loudspeaker damage. POWER DISSIPATION Power dissipation is a major concern when designing a successful amplifier, whether the amplifier is bridged or single-ended. Equation 1 states the maximum power dissi- pation point for a bridge amplifier operating at a given supply voltage and driving a specified output load. P DMAX =( VDD )2/(2π2R L) Single-Ended (1) However, a direct consequence of the increased power de- livered to the load by a bridge amplifier is an increase in internal power dissipation point for a bridge amplifier oper- ating at the same conditions. P DMAX = 4(VDD )2/(2π2R L) Bridge Mode (2) Since the LM4900 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 LM4900 does not require heatsinking. From Equation 1, assuming a 5V power supply and an 8Ω load, the maximum power dissipation point is 625 mW. The maximum power dissipation point obtained from Equation 2 must not be greater than the power dissi- pation that results from Equation 3: P DMAX =( TJMAX −T A)/θJA (3) For package MUA08A, θJA = 190˚C/W. TJMAX = 150˚C for the LM4900. Depending on the ambient temperature, TA,o f 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 2 is greater than that of Equation 3, then either the supply voltage must be de- creased, the load impedance increased, the ambient tem- perature reduced, or theθ JA reduced with heatsinking. In many cases larger traces near the output, VDD , and Gnd pins can be used to lower theθJA. The larger areas of copper provide a form of heatsinking allowing a higher power dissi- pation. 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 ap- proximately 30˚C provided that device operation is around the maximum power dissipation point. Internal power dissi- pation is a function of output power. If typical operation is not around the maximum power dissipation point, the ambient temperature can be increased. Refer to theTypical Perfor- mance Characteristicscurves for power dissipation infor- mation for lower output powers. LM4900 www.national.com13

is improved PSRR due to increased half-supply stability. amplifier off when a logic high is placed on the shutdown pin. voltage to avoid unwanted state changes. Figure 1. The input coupling capacitor, Ci, forms a frequency response for a few distinct reasons. input capacitor may not increase system performance. turn-on pops can be minimized. 1⁄2 VDD ), the smaller the turn-on pop. is recommended in all but the most cost sensitive designs. explained in thePower Dissipationsection.

Application Information(Continued) (5) R F/Ri =A VD /2 (6) From Equation 5, the minimum AVD is 1.55; use AVD =2 . Since the desired input impedance was 20 kΩ , and with a AVD of 2, a ratio of 1:1 of RF to Riresults in an allocation of R i =R F =2 0k Ω . The final design step is to address the bandwidth requirements which must be stated as a pair of −3 dB frequency points. Five times away from a pole gives 0.17 dB down from passband response which is better than the required ±0.25 dB specified. fL = 100Hz/5 = 20Hz fH = 20kHz x 5 = 100kHz As stated in theExternal Components section, Ri in con- junction with Cicreate a highpass filter. C i≥ 1/(2π*20 kΩ *20 Hz) = 0.397µF; use 0.39µF 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 LM4900 GBWP of 25MHz. This figure displays that if a designer has a need to design an amplifier with a higher differential gain, the LM4900 can still be used without running into bandwidth problems. LM4900 www.national.com15

FIGURE 2. Differential Amplifier Configuration for LM4900

Physical Dimensionsinches (millimeters) unless otherwise noted 8-Lead (0.118" Wide) Molded Mini Small Outline Package Order Number LM4900MM LM4900 www.national.com17

Physical Dimensionsinches (millimeters) unless otherwise noted (Continued) Order Number LM4900LD SO Order Number LM4900M LM4900 www.national.com 18

NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. National Semiconductor Corporation Americas Email: support@nsc.com National Semiconductor Europe Fax: +49 (0) 180-530 85 86 Email: europe.support@nsc.com Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Français Tel: +33 (0) 1 41 91 8790 National Semiconductor Asia Pacific Customer Response Group Tel: 65-2544466 Fax: 65-2504466 Email: ap.support@nsc.com National Semiconductor Japan Ltd. Tel: 81-3-5639-7560 Fax: 81-3-5639-7507 www.national.com LM4900 265mW at 3.3V Supply Audio Power Amplifier with Shutdown Mode National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.