LM4868LQX National Semiconductor, LM4868LQX Datasheet

LM4868LQX

Manufacturer Part Number
LM4868LQX
Description
Manufacturer
National Semiconductor
Datasheet

Specifications of LM4868LQX

Operational Class
Class-AB
Audio Amplifier Output Configuration
2-Channel Stereo
Output Power (typ)
3W
Audio Amplifier Function
Headphone/Speaker
Total Harmonic Distortion
0.30%%
Single Supply Voltage (typ)
3/5V
Dual Supply Voltage (typ)
Not RequiredV
Power Supply Requirement
Single
Rail/rail I/o Type
No
Power Supply Rejection Ratio
67dB
Single Supply Voltage (min)
2V
Single Supply Voltage (max)
5.5V
Dual Supply Voltage (min)
Not RequiredV
Dual Supply Voltage (max)
Not RequiredV
Operating Temp Range
-40C to 85C
Operating Temperature Classification
Industrial
Mounting
Surface Mount
Pin Count
24
Package Type
LLP EP
Lead Free Status / Rohs Status
Not Compliant

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
LM4868LQX
Manufacturer:
HIT
Quantity:
80
Part Number:
LM4868LQX
Manufacturer:
NS/国半
Quantity:
20 000
© 2002 National Semiconductor Corporation
LM4868
Output-Transient-Free Dual 2.1W Audio Amplifier Plus
No Coupling Capacitor Stereo Headphone Function
General Description
The LM4868 is a dual bridge-connected audio power ampli-
fier which, when connected to a 5V supply, will deliver 2.1W
to a 4Ω load (Note 1) or 2.4W to a 3Ω load (Note 2) with less
than 1.0% THD+N. The LM4868 uses advanced, latest gen-
eration circuitry to eliminate all traces of clicks and pops
when the supply voltage is first applied. The amplifier has a
headphone-amplifier-select input pin. It is used to switch the
amplifiers from bridge to single-ended mode for driving
headphones. A new circuit topology eliminates headphone
output coupling capacitors (patent pending). A MUX control
pin allows selection between the two sets of stereo input
signals. The MUX control can also be used to select be-
tween two different customer-specified closed-loop re-
sponses.
Boomer audio power amplifiers are designed specifically to
provide high quality output power from a surface mount
package and require few external components. To simplify
audio system design, the LM4868 combines dual bridge
speaker amplifiers and stereo headphone amplifiers in one
package.
The LM4868 features an externally controlled power-saving
micropower shutdown mode, a stereo headphone amplifier
mode, and thermal shutdown protection.
Note 1: An LM4868LQ or LM4868MTE that has been properly mounted to
a circuit board will deliver 2.1W into 4Ω. The Mux control can also be used to
select two different closed-loop responses. LM4868MT will deliver 1.1W into
8Ω. See the Application Information sections for further information concern-
ing the LM4868LQ and the LM4868MT.
Note 2: An LM4868LQ or LM4868MTE that has been properly mounted to a
circuit board and forced-air cooled will deliver 2.4W into 3Ω.
Connection Diagrams
Boomer
®
is a registered trademark of National Semiconductor Corporation.
See NS Package Number MXA20A for Exposed-DAP TSSOP
See NS Package Number MTC20 for TSSOP
DS200267
Order Number LM4868MT, LM4868MTE
Top View
Key Specifications
n P
n
n
n
n
n Single-ended mode - THD+N at 75mW into 32Ω
n Shutdown current
Features
n Advanced “click and pop” suppression circuitry
n Eliminates headphone amplifier output coupling
n Stereo headphone amplifier mode
n Input mux control and two separate inputs per channel
n Thermal shutdown protection circuitry
n LLP, TSSOP, and exposed-DAP TSSOP packaging
Applications
n Multimedia monitors
n Portable and desktop computers
n Portable audio systems
(max)
capacitors (patent pending)
available
O
LM4868LQ, 3Ω load
LM4868LQ, 4Ω load
LM4868MTE, 4Ω
LM4868MT, 8Ω
at 1% THD+N
20026758
www.national.com
August 2002
0.7µA (typ)
2.4W (typ)
2.1W (typ)
1.9W (typ)
1.1W (typ)
0.5%

Related parts for LM4868LQX

LM4868LQX Summary of contents

Page 1

... Note 2: An LM4868LQ or LM4868MTE that has been properly mounted to a circuit board and forced-air cooled will deliver 2.4W into 3Ω. Connection Diagrams See NS Package Number MXA20A for Exposed-DAP TSSOP Boomer ® registered trademark of National Semiconductor Corporation. © 2002 National Semiconductor Corporation Key Specifications THD+N O LM4868LQ, 3Ω ...

Page 2

Connection Diagrams See NS Package Number LQA24A for Exposed-DAP LLP Typical Application * Refer to the Application Information section titled PROPER SELECTION OF EXTERNAL COMPONENTS for details concerning the value of C FIGURE 1. Typical Audio Amplifier Application Circuit (Pin ...

Page 3

... 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 4) ESD Susceptibility (Note 5) All pins except Pin 3 (MT, MTE), Pin 2 (LQ) Pin 3 (MT, MTE), Pin 2 (LQ) ...

Page 4

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

Page 5

Typical Performance Characteristics MTE- and LQ- Specific Characteristics LM4868MTE THD+N vs Output Power LM4868LQ THD+N vs Output Power LM4868MTE THD+N vs Output Power 20026733 20026753 20026736 5 LM4868MTE THD+N vs Frequency 20026734 LM4868LQ THD+N vs Frequency 20026754 LM4868LQ THD+N vs ...

Page 6

Typical Performance Characteristics MTE- and LQ- Specific Characteristics LM4868LQ, LM4868MTE Power Dissipation vs Power Output LM4868LQ Power Derating Curve Note 18: This curve shows the LM4868MTE’s thermal dissipation ability at different ambient temperatures given these conditions: 500LFPM + JEDEC board: ...

Page 7

Typical Performance Characteristics THD+N vs Frequency THD+N vs Frequency THD+N vs Output Power 20026703 THD+N vs Output Power 20026705 THD+N vs Output Power 20026707 7 THD+N vs Frequency 20026704 20026706 20026708 www.national.com ...

Page 8

Typical Performance Characteristics THD+N vs Output Power THD+N vs Output Power Output Power vs Load Resistance www.national.com (Continued) 20026765 20026766 20026762 8 THD+N vs Frequency 20026763 THD+N vs Frequency 20026764 Power Dissipation vs Supply Voltage 20026760 ...

Page 9

Typical Performance Characteristics Output Power vs Supply Voltage Output Power vs Supply Voltage Output Power vs Load Resistance (Continued) 20026709 20026711 20026713 9 Output Power vs Supply Voltage 20026710 Output Power vs Load Resistance 20026712 Power Dissipation vs Output Power ...

Page 10

Typical Performance Characteristics Dropout Voltage vs Supply Voltage Power Dissipation vs Output Power Channel Separation www.national.com (Continued) 20026715 20026717 20026719 10 Power Derating Curve 20026716 Noise Floor 20026718 Channel Separation 20026720 ...

Page 11

Typical Performance Characteristics Power Supply Rejection Ratio Supply Current vs Supply Voltage ( Refer to Figure 1. ) Components 1. R This is the inverting input resistance that sets the closed-loop gain in conjunction with R i forms a high ...

Page 12

Application Information headphones. The headphones operate in a manner very similar to a bridge-tied-load (BTL). The same DC voltage is applied to both headphone speaker terminals. This results in no net DC current flow through the speaker. AC current flows ...

Page 13

Application Information FIGURE 4. Typical Audio Amplifier Application Circuit (Pin out shown for the 24-pin Exposed-DAP LLP package. Numbers are for the 20-pin MTE and MT packages.) FIGURE 5. Input MUX Example STEREO-INPUT MULTIPLEXER (STEREO MUX) The ...

Page 14

Application Information present on the internal amplifier’s input may change. This change can slew at a rate that may produce audible voltage transients or clicks in the amplifier’s output signal. Using the MUX to select between two vastly dissimilar gains ...

Page 15

Application Information tical in magnitude, but 180˚ out of phase. Taking advantage of this phase difference, a load is placed between -OUTA and +OUTA and driven differentially (’commonly referred to as bridge mode’). This results in a differential gain of ...

Page 16

Application Information pop performance. The selection of bypass capacitor values, especially C , depends on desired PSRR requirements, B click and pop performance (as explained in the section, Proper Selection of External Components), system cost, and size constraints. MICRO−POWER SHUTDOWN ...

Page 17

Application Information FIGURE 7. The PCDN042 provides additional ESD protection beyond the 8000V shown in the Absolute Maximum Ratings for the AMP2A output Single-Ended Output Power Performance and Measurement Considerations The LM4868 delivers clean, low distortion SE output power into ...

Page 18

Application Information V ), the smaller the turn-on pop. Choosing C DD 1.0µF along with a small value 0.39µF), produces a click-less and pop-less shutdown func- tion. As discussed above, choosing C sary for the desired bandwidth ...

Page 19

Application Information f = 100Hz/5 = 20Hz L and 20kHz 100kHz H As mentioned in the Selecting Proper External Compo- nents section, R and C create a highpass filter that sets the i i ...

Page 20

Application Information www.national.com (Continued) FIGURE 10. Recommended LQ PC Board Layout: Component-Side Layout FIGURE 11. Recommended LQ PC Board Layout: Upper Inner-Layer Layout 20 20026741 20026742 ...

Page 21

Application Information FIGURE 12. Recommended LQ PC Board Layout: FIGURE 13. Recommended LQ PC Board Layout: (Continued) Lower Inner-Layer Layout Bottom-Side Layout 21 20026743 20026744 www.national.com ...

Page 22

Application Information www.national.com (Continued) FIGURE 14. Recommended MTE PC Board Layout: Component-Side Silkscreen FIGURE 15. Recommended MTE PC Board Layout: Component-Side Layout 22 20026770 20026771 ...

Page 23

Application Information FIGURE 16. Recommended MTE PC Board Layout: FIGURE 17. Recommended MTE PC Board Layout: (Continued) Upper Inner-Layer Layout Lower Inner-Layer Layout 23 20026772 20026773 www.national.com ...

Page 24

Application Information www.national.com (Continued) FIGURE 18. Recommended MTE PC Board Layout: Bottom-Side Layout FIGURE 19. Recommended MT PC Board Layout: Component-Side Silkscreen 24 20026774 20026775 ...

Page 25

Application Information FIGURE 20. Recommended MT PC Board Layout: FIGURE 21. Recommended MT PC Board Layout: (Continued) Component-Side Layout Bottom-Side Layout 25 20026776 20026777 www.national.com ...

Page 26

Physical Dimensions 24-Lead MOLDED PKG, Leadless Leadframe Package LLP 20-Lead MOLDED PKG, TSSOP, JEDEC, 4.4mm BODY WIDTH www.national.com inches (millimeters) unless otherwise noted Order Number LM4868LQ NS Package Number LQA24A Order Number LM4868MT NS Package Number MTC20 26 ...

Page 27

Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 20-Lead MOLDED TSSOP, EXPOSED PAD, 6.5x4.4x0.9mm Order Number LM4868MTE NS Package Number MXA20A 27 www.national.com ...

Page 28

... 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 ...

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