lm4838mtx

Manufacturer Part Numberlm4838mtx
DescriptionStereo 2w Audio Power Amplifiers With Dc Volume Control And Selectable Gain
ManufacturerNational Semiconductor Corporation
lm4838mtx datasheet
 


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LM4838
Stereo 2W Audio Power Amplifiers
with DC Volume Control and Selectable Gain
General Description
The LM4838 is a monolithic integrated circuit that provides
DC volume control, and stereo bridged audio power amplifi-
ers capable of producing 2W into 4Ω (Note 1) with less than
1.0% THD or 2.2W into 3Ω (Note 2) with less than 1.0%
THD.
Boomer
®
audio integrated circuits were designed specifically
to provide high quality audio while requiring a minimum
amount of external components. The LM4838 incorporates a
DC volume control, stereo bridged audio power amplifiers
and a selectable gain or bass boost, making it optimally
suited for multimedia monitors, portable radios, desktop, and
portable computer applications.
The LM4838 features an externally controlled, low-power
consumption shutdown mode, and both a power amplifier
and headphone mute for maximum system flexibility and
performance.
Note 1: When properly mounted to the circuit board, the LM4838LQ,
LM4838MTE, and LM4838GR will deliver 2W into 4Ω. The LM4838MT and
LM4838ITL will deliver 1.1W into 8Ω. See Application Information section
Exposed-DAP package PCB Mounting Considerations for more informa-
tion.
Note 2: An LM4838LQ and LM4838MTE that have been properly mounted
to the circuit board and forced-air cooled will deliver 2.2W into 3Ω.
Block Diagram
Boomer
®
is a registered trademark of NationalSemiconductor Corporation.
© 2004 National Semiconductor Corporation
Key Specifications
n P
at 1% THD+N
O
into 3Ω (LQ & MTE)
n
into 4Ω (LQ, MTE, GR)
n
into 8Ω (MT, MTE, ITL, LQ, & GR)
n
n Single-ended mode - THD+N at 85mW into
32Ω
n Shutdown current
Features
n DC Volume Control Interface
n System Beep Detect
n Stereo switchable bridged/single-ended power amplifiers
n Selectable internal/external gain and bass boost
n “Click and pop” suppression circuitry
n Thermal shutdown protection circuitry
Applications
n Portable and Desktop Computers
n Multimedia Monitors
n Portable Radios, PDAs, and Portable TVs
FIGURE 1. LM4838 Block Diagram
DS200133
November 2004
2.2W (typ)
2.0W (typ)
1.1W (typ)
1.0%(typ)
0.7µA (typ)
20013301
www.national.com

lm4838mtx Summary of contents

  • Page 1

    ... Note 2: An LM4838LQ and LM4838MTE that have been properly mounted to the circuit board and forced-air cooled will deliver 2.2W into 3Ω. Block Diagram Boomer ® registered trademark of NationalSemiconductor Corporation. © 2004 National Semiconductor Corporation Key Specifications THD+N O into 3Ω (LQ & MTE) n into 4Ω ...

  • Page 2

    Connection Diagrams See NS Package Number LQA028AA for Exposed-DAP LLP See NS Package Number MXA28A for Exposed-DAP TSSOP www.national.com LLP Package Top View Order Number LM4838LQ TSSOP Package Top View Order Number LM4838MT See NS Package Number MTC28 for TSSOP ...

  • Page 3

    Connection Diagrams 6 NC Right Out - 5 GND Right Gain 2 4 Bypass Sense NC 2 GND Left Gain Left Out - Pin A Designator (Continued) 36 Bump micro SMD 20013388 Top View ...

  • Page 4

    Connection Diagrams 7 Right Out - Right Gain 1 6 Right Out - Right Gain 2 5 VDD VDD 4 Right Out + Right Out + 3 GND GND 2 Shutdown Gain Select 1 Mode Mute Pin A Designator www.national.com ...

  • Page 5

    Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage Storage Temperature Input Voltage Power Dissipation (Note 11) ESD Susceptibility (Note 12) ESD Susceptibility (Note 13) Junction ...

  • Page 6

    Electrical Characteristics for Single-Ended Mode Operation 10) (Continued) The following specifications apply for V Symbol Parameter THD+N Total Harmonic Distortion+Noise PSRR Power Supply Rejection Ratio SNR Signal to Noise Ratio X Channel Separation talk Electrical Characteristics for Bridged Mode Operation ...

  • Page 7

    Electrical Characteristics for Bridged Mode Operation Note 16: All bumps have the same thermal resistance and contribute equally when used to lower thermal resistance. The LM4838ITL demo board (views featured in the Application Information section four layer board ...

  • Page 8

    Typical Performance Characteristics MTE Specific Characteristics LM4838MTE THD+N vs Output Power LM4838MTE THD+N vs Output Power LM4838MTE Power Dissipation vs Output Power Note 19: These curves show the thermal dissipation ability of the LM4838MTE at different ambient temperatures given these ...

  • Page 9

    Typical Performance Characteristics Non-MTE Specific Characteristics THD+N vs Frequency THD+N vs Frequency THD+N vs Frequency THD+N vs Frequency 20013357 THD+N vs Frequency 20013314 THD+N vs Frequency 20013316 9 20013358 20013315 20013317 www.national.com ...

  • Page 10

    Typical Performance Characteristics Non-MTE Specific Characteristics THD+N vs Frequency THD+N vs Frequency THD+N vs Frequency www.national.com (Continued) THD+N vs Frequency 20013318 THD+N vs Frequency 20013320 THD+N vs Output Power 20013322 10 20013319 20013321 20013324 ...

  • Page 11

    Typical Performance Characteristics Non-MTE Specific Characteristics THD+N vs Output Power THD+N vs Output Power THD+N vs Output Power (Continued) THD+N vs Output Power 20013325 THD+N vs Output Power 20013327 THD+N vs Output Power 20013329 11 20013326 20013328 20013330 www.national.com ...

  • Page 12

    Typical Performance Characteristics Non-MTE Specific Characteristics THD+N vs Output Power THD+N vs Output Power THD+N vs Output Voltage Docking Station Pins www.national.com (Continued) THD+N vs Output Power 20013331 THD+N vs Output Power 20013333 THD+N vs Output Voltage Docking Station Pins ...

  • Page 13

    Typical Performance Characteristics Output Power vs Load Resistance Output Power vs Load Resistance Power Supply Rejection Ratio 20013362 20013306 20013339 13 Dropout Voltage 20013353 Output Power vs Load Resistance 20013307 Output Power vs Load Resistance 20013308 www.national.com ...

  • Page 14

    Typical Performance Characteristics Noise Floor Volume Control Characteristics Power Dissipation vs Output Power www.national.com (Continued) 20013341 Bass Boost Characteristics 20013340 Power Dissipation vs 20013351 14 Noise Floor 20013342 External Gain/ 20013361 Output Power 20013352 ...

  • Page 15

    Typical Performance Characteristics Power Derating Curve Output Power vs Supply voltage Supply Current vs Supply Voltage Note 20: These curves show the thermal dissipation of the LM4838ITL at different ambient temperatures with a thermal plane of size shown on an ...

  • Page 16

    Application Information EXPOSED-DAP PACKAGE PCB MOUNTING CONSIDERATIONS The LM4838’s exposed-DAP (die attach paddle) packages (MTE, LQ) provide a low thermal resistance between the die and the PCB to which the part is mounted and soldered. This allows rapid heat transfer ...

  • Page 17

    Application Information amplifier’s half-supply bias voltage across the load. This increases internal IC power dissipation and may perma- nently damage loads such as speakers. POWER DISSIPATION Power dissipation is a major concern when designing a successful single-ended or bridged amplifier. ...

  • Page 18

    Application Information INPUT CAPACITOR VALUE SELECTION Amplifying the lowest audio frequencies requires a high value input coupling capacitor (0.33µF in Figure 2), but high value capacitors can be expensive and may compromise space efficiency in portable designs. In many cases, ...

  • Page 19

    Application Information MICRO-POWER SHUTDOWN The voltage applied to the SHUTDOWN pin controls the LM4838’s shutdown function. Activate micro-power shut- down by applying V to the SHUTDOWN pin. When active, DD the LM4838’s micro-power shutdown feature turns off the amplifier’s bias ...

  • Page 20

    Application Information GAIN SELECT FUNCTION (Bass Boost) The LM4838 features selectable gain, using either internal or external feedback resistors. Either set of feedback resistors set the gain of the output amplifiers. The voltage applied to the GAIN SELECT pin controls ...

  • Page 21

    Application Information VOLUME CONTROL TABLE ( Table 2 ) Gain Voltage Range (% of Vdd) (dB) Low High Recommended 0 77.5% 100.00% 100.000% -1 75.0% 78.5% 76.875% -2 72.5% 76.25% 74.375% -3 70.0% 73.75% 71.875% -4 67.5% 71.25% 69.375% -5 ...

  • Page 22

    Application Information AUDIO POWER AMPLIFIER DESIGN Audio Amplifier Design: Driving 1W into an 8Ω Load The following are the desired operational parameters: Power Output: Load Impedance: Input Level: Input Impedance: Bandwidth: 100 Hz−20 kHz The design begins by specifying the ...

  • Page 23

    Recommended Printed Circuit Board Layout FIGURE 5. Recommended LQ PC Board Layout: FIGURE 6. Recommended LQ PC Board Layout: (Continued) Component-Side Silkscreen Component-Side Layout 23 20013377 20013378 www.national.com ...

  • Page 24

    Recommended Printed Circuit Board Layout www.national.com FIGURE 7. Recommended LQ PC Board Layout: Upper Inner-Layer Layout FIGURE 8. Recommended LQ PC Board Layout: Lower Inner-Layer Layout 24 (Continued) 20013379 20013380 ...

  • Page 25

    Recommended Printed Circuit Board Layout FIGURE 9. Recommended LQ PC Board Layout: (Continued) Bottom-Side Layout 25 20013381 www.national.com ...

  • Page 26

    Item Part Number Part Description 1 551011368-001 LM4838 Eval Board PCB etch 001 10 482911368-001 LM4838 28L LLP 20 151911368-001 Cer Cap 0.068µF 50V 10% 1206 25 152911368-001 Tant Cap 0.1µF 10V 10% Size = A 3216 26 152911368-002 Tant ...

  • Page 27

    LM4838 MT & MTE Demo Board Artwork Top Layer SilkScreen Top Layer TSSOP 27 20013382 20013383 www.national.com ...

  • Page 28

    LM4838 MT & MTE Demo Board Artwork www.national.com (Continued) Inner Layer (2) LM4838MT/MTE Inner Layer (3) LM4838MT/MTE 28 20013385 20013386 ...

  • Page 29

    LM4838 MT & MTE Demo Board Artwork Item Part Number 1 551011373-001 10 482911373-001 20 151911368-001 25 152911368-001 26 152911368-002 27 152911368-003 28 152911368-004 29 152911368-005 30 472911368-001 31 472911368-002 32 472911368-003 33 472911368-004 (Continued) Bottom Layer TSSOP Analog Audio ...

  • Page 30

    Item Part Number 40 131911368-001 41 131911368-002 42 131911368-003 43 131911368-004 44 131911368-005 45 131911368-006 www.national.com Analog Audio LM4838 TSSOP Eval Board Assembly Part Number: 980011373-100 Revision: A Bill of Material (Continued) Part Description Qty Stereo Headphone Jack 1 W/ ...

  • Page 31

    LM4838 ITL Demo Board Artwork FIGURE 10. LM4838 micro SMD Silk Screen FIGURE 11. LM4838 micro SMD Top Layer 31 20013392 20013389 www.national.com ...

  • Page 32

    LM4838 ITL Demo Board Artwork www.national.com (Continued) FIGURE 12. LM4838 micro SMD Upper Inner Layer FIGURE 13. LM4838 micro SMD Lower Inner Layer 32 20013390 20013391 ...

  • Page 33

    LM4838 ITL Demo Board Artwork (Continued) FIGURE 14. LM4838 micro SMD Bottom Layer 33 20013393 www.national.com ...

  • Page 34

    Part Description µΩ LM4838 TLA36 Evaluation Board PCB LM4838ITL Ceramic Capacitor 0.068µF 50V 10% Size = 1206 Tantalum Capacitor 0.1µF 10V 10% Size = 1206 Tantalum Capacitor 0.33µF 10V 10% Size = 1206 Tantalum Capacitor 1.0µF 16V 10% Size = ...

  • Page 35

    Physical Dimensions inches (millimeters) unless otherwise noted NS Package Number LQA028AA For Exposed-DAP LLP LLP Package Order Number LM4838LQ 35 www.national.com ...

  • Page 36

    Physical Dimensions NS Package Number MXA28A for Exposed-DAP TSSOP www.national.com inches (millimeters) unless otherwise noted (Continued) TSSOP Package Order Number LM4838MT NS Package Number MTC28 for TSSOP Exposed-DAP TSSOP Package Order Number LM4838MTE 36 ...

  • Page 37

    Physical Dimensions inches (millimeters) unless otherwise noted (Continued 3.000 1 36-Bump micro SMD Order Number LM4838ITL, LM4838ITLX NS Package Number TLA36AAA ± ± 0. 3.000 0. 0.600 ± 0.075 www.national.com ...

  • Page 38

    Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 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 ...