LM4891
1Watt Audio Power Amplifier
General Description
The LM4891is an audio power amplifier primarily designed for demanding applications in mobile phones and other por-table communication device applications.It is capable of delivering 1watt of continuous average power to an 8ΩBTL load with less than 1%distortion (THD+N)from a 5V DC power supply.
Boomer audio power amplifiers were designed specifically to provide high quality output power with a minimal amount of external components.The LM4891does not require output coupling capacitors or bootstrap capacitors,and therefore is ideally suited for mobile phone and other low voltage appli-cations where minimal power consumption is a primary re-quirement.
The LM4891features a low-power consumption shutdown mode,which is achieved by driving the shutdown pin with logic high.Additionally,the LM4891features an internal ther-mal shutdown protection mechanism.
The LM4891contains advanced pop &click circuitry which eliminates nois which would otherwi occur during turn-on and turn-off transitions.
The LM4891is unity-gain stable and can be configured by external gain-tting resistors.
Key Specifications
j PSRR at 217Hz,V DD =5V,8ΩLoad 62dB (typ)j Power Output at 5.0V &1%THD 1.0W (typ)j Power Output at 3.3V &1%THD 400mW (typ)j Shutdown Current
0.1µA (typ)
Features
n Available in space-saving packages:micro SMD,MSOP ,SOIC,and LLP
n Ultra low current shutdown mode
n BTL output can drive capacitive loads
n Improved pop &click circuitry eliminates nois during turn-on and turn-off transitions n 2.2to 5.5V operation
n No output coupling capacitors,snubber networks or bootstrap capacitors required n Thermal shutdown protection n Unity-gain stable
n External gain configuration capability
Applications
n Mobile Phones n PDAs
n Portable electronic devices
Typical Application
Boomer ®is a registered trademark of National Semiconductor Corporation.
©2002National Semiconductor Corporation
Connection Diagrams
8Bump micro SMD
Small Outline (SO)Package
20007435
Top View
Order Number LM4891M See NS Package Number M08A
8Bump micro SMD Marking SO Marking
怎样做梅干菜20007470Top View X -Date Code T -Die Traceability G -Boomer Family G -LM4891IBP
20007472
Top View XY -Date Code TT -Die Traceability
Bottom 2lines -Part Number
Mini Small Outline (MSOP)Package
MSOP Marking
20007436
Top View
Order Number LM4891MM See NS Package Number MUA08A
20007471
Top View
G -Boomer Family 91-LM4891MM LLP Package
10Pin LLP Marking
20007480
Top View
Order Number LM4891LD
See NS Package Number LDA10B
20007479
Top View
Z -Asmbly Plant Code (M for Malacca)
XY -2Digit Datecode
TT -2Letter Code for Traceability
L4891-LM4891LD
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Absolute Maximum Ratings(Note2) If Military/Aerospace specified devices are required, plea contact the National Semiconductor Sales Office/ Distributors for availability and specifications.
Supply Voltage(Note11) 6.0V Storage Temperature−65˚C to+150˚C Input Voltage−0.3V to V DD+0.3V Power Dissipation(Note3)Internally Limited ESD Susceptibility(Note4)2000V ESD Susceptibility(Note5)250V Junction Temperature150˚C Thermal Resistance
θJC(SOP)35˚C/W θJA(SOP)150˚C/W θJA(micro SMD)220˚C/W
θJC(MSOP)56˚C/W θJA(MSOP)190˚C/W θJA(LLP)220˚C/W Soldering Information
See AN-1112"microSMD Wafers Level Chip Scale Package".
See AN-1187"Leadlesss
Leadframe Package(LLP)".
Operating Ratings
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Temperature Range
T MIN≤T A≤T MAX−40˚C≤T A≤85˚C Supply Voltage 2.2V≤V DD≤5.5V
Electrical Characteristics V
DD =5V(Notes1,2,8)
The following specifications apply for V DD=5V,A V=2,and8Ωload unless otherwi specified.Limits apply for T A=25˚C.
Symbol Parameter Conditions
LM4891
Units
(Limits) Typical Limit
(Note6)(Note7)
I DD Quiescent Power Supply Current V IN=0V,I o=0A410mA(max) I SD Shutdown Current V shutdown=V DD0.1µA(max) P o Output Power THD=2%(max);f=1kHz1W THD+N Total Harmonic Distortion+Noi P o=0.4Wrms;f=1kHz0.1% PSRR Power Supply Rejection Ratio V ripple=200mV sine p-p62(f=
217Hz)
66(f=1kHz)
dB
Electrical Characteristics V
DD =3.3V(Notes1,2,8)
The following specifications apply for V DD=3.3V,A V=2,and8Ωload unless otherwi specified.Limits apply for T A=25˚C.
Symbol Parameter Conditions
LM4891
Units
(Limits) Typical Limit
(Note6)(Note7)
I DD Quiescent Power Supply Current V IN=0V,I o=0A 3.5mA(max) I SD Shutdown Current V shutdown=V DD0.1µA(max) P o Output Power THD=1%(max);f=1kHz0.4W THD+N Total Harmonic Distortion+Noi P o=0.15Wrms;f=1kHz0.1% PSRR Power Supply Rejection Ratio V ripple=200mV sine p-p60(f=愿景是什么意思
217Hz)
62(f=1kHz)
dB
Electrical Characteristics V
DD =2.6V(Notes1,2,8)
The following specifications apply for V DD=2.6V,A V=2,and8ΩLoad unless otherwi specified.Limits apply for T A= 25˚C.
Symbol Parameter Conditions
LM4891
Units
(Limits) Typical Limit
(Note6)(Note7)
I DD Quiescent Power Supply Current V IN=0V,I o=0A 2.6mA(max)
I SD Shutdown Current V shutdown=V DD0.1µA(max)
LM4891
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Electrical Characteristics V DD =2.6V (Notes 1,2,8)
The following specifications apply for V DD =2.6V,A V =2,and 8ΩLoad unless otherwi specified.Limits apply for T A =25˚C.(Continued)如何上国外网站
Symbol Parameter
Conditions
LM4891
Units (Limits)Typical Limit (Note 6)(Note 7)
P 0Output Power (8Ω)Output Power (4Ω)
THD =1%(max);f =1kHz THD =1%(max);f =1kHz 0.250.28W W THD+N Total Harmonic Distortion+Noi P o =0.1Wrms;f =1kHz 0.08%PSRR
Power Supply Rejection Ratio
V ripple =200mV sine p-p
44(f =217Hz)44(f =1kHz)
dB
Note 1:All voltages are measured with respect to the ground pin,unless otherwi 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 T JMAX ,θJA ,and the ambient temperature T A .The maximum allowable power dissipation is P DMAX =(T JMAX –T A )/θJA or the number given in Absolute Maximum Ratings,whichever is lower.For the LM4891,e power derating curves for additional information.
Note 4:Human body model,100pF discharged through a 1.5k Ωresistor.Note 5:Machine Model,220pF
–240pF discharged through all pins.Note 6:Typicals are measured at 25˚C and reprent the parametric norm.
Note 7:Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).
Note 8:For micro SMD only,shutdown current is measured in a Normal Room Environment.Exposure to direct sunlight will increa I SD by a maximum of 2µA.Note 9:Datasheet min/max specification limits are guaranteed by design,test,or statistical analysis.
Note 10:ROUT is measured from each of the output pins to ground.This value reprents the parallel combination of the 10k ohm output resistors and the two 20k ohm resistors.
戚继光Note 11:If the product is in shutdown mode and V DD exceeds 6V (to a max of 8V V DD ),then most of the excess current will flow through the ESD protection circuits.If the source impedance limits the current to a max of 10ma,then the part will be protected.If the part is enabled when V DD is greater than 5.5V and less than 6.5V,no damage will occur,although operational life will be reduced.Operation above 6.5V with no current limit will result in permanent damage.
Note 12:All bumps have the same thermal resistance and contribute equally when ud to lower thermal resistance.All bumps must be connected to achieve specified thermal resistance.
Note 13:Maximum power dissipation (P DMAX )in the device occurs at an output power level significantly below full output power.P DMAX can be calculated using Equation 1shown in the Application ction.It may also be obtained from the power dissipation graphs.
Note 14:PSRR is a function of system gain.Specifications apply to the circuit in Figure 1where A V =2.Higher system gains will reduce PSRR value by the amount of gain increa.A system gain of 10reprents a gain increa of 14dB.PSRR will be reduced by 14dB and applies to all operating voltages.
External Components Description
(Figure 1)Components Functional Description
1.R i Inverting input resistance which ts the clod-loop gain in conjunction with R f .This resistor also forms a high pass filter with C i at f C =1/(2πR i C i ).
2.
C i
Input coupling capacitor which blocks the DC voltage at the amplifiers input terminals.Also creates a
highpass filter with R i at f c =1/(2πR i C i ).Refer to the ction,Proper Selection of External Components ,for an explanation of how to determine the value of C i .
3.R f Feedback resistance which ts the clod-loop gain in conjunction with R i .
4.C S Supply bypass capacitor which provides power supply filtering.Refer to the Power Supply Bypassing ction for information concerning proper placement and lection of the supply bypass capacitor.
5.
C B
Bypass pin capacitor which provides half-supply filtering.Refer to the ction,Proper Selection of External Components ,for information concerning proper placement and lection of C B .
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Typical Performance Characteristics
THD+N vs Frequency
at V DD=5V,8ΩR L,and PWR=250mW
THD+N vs Frequency
at V DD=3.3V,8ΩR L,and PWR=150mW
2000743720007438
THD+N vs Frequency
at V DD=2.6V,8ΩR L,and PWR=100mW
THD+N vs Frequency
at V DD=2.6V,4ΩR L,and PWR=100mW
2000743920007440
THD+N vs Power Out @V DD=5V,8ΩR L,1kHz
THD+N vs Power Out
@V DD=3.3V,8ΩR L,1kHz
2000744120007442
LM4891
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Typical Performance Characteristics
(Continued)
THD+N vs Power Out
@V DD =2.6V,8ΩR L ,1kHz
THD+N vs Power Out
@V DD =2.6V,4ΩR L ,1kHz
2000744320007444
Power Supply Rejection Ratio (PSRR)@V DD =5V Power Supply Rejection Ratio (PSRR)@V DD =5V
20007445Input terminated with 10ΩR
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20007473
Input Floating
Power Supply Rejection Ratio (PSRR)@V DD =2.6V
Power Supply Rejection Ratio (PSRR)@V DD =3.3V
20007447Input terminated with 10ΩR 20007446
Input terminated with 10ΩR
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