NSC LM4873MTX, LM4873MTEX-1, LM4873MTEX, LM4873MTE-1, LM4873MT Datasheet

LM4873

Dual 2.1W Audio Amplifier Plus Stereo Headphone
Function

General Description

The LM4873 is a dual bridge-connected audio power ampli­fier which, when connected to a 5V supply, will deliver 2.1W
toa4Ωload (Note 1) or 2.4W to a 3Ω load (Note 2)with less
than 1.0% THD+N. In addition, the headphone input pin al­lows the amplifiers to operate in single-ended mode to drive
stereo headphones. A Mux Control pin toggles between the
two stereo sets of amplifier inputs, allowing for two select­able amplifier closed-loop responses.

Boomer audio power amplifiers were designed specifically to
provide high quality output power from a surface mount
package while requiring few external components. To sim­plify audio system design, the LM4873 combines dual bridge
speaker amplifiers and stereo headphone amplifiers on one
chip.

The LM4873 features an externally controlled, low-power
consumption shutdown mode, a stereo headphone amplifier
mode, and thermal shutdown protection. It also utilizes cir­cuitry to reduce “clicks and pops” during device turn-on.

Note 1: An LM4873MTE-1 which has been properly mounted to the circuit
board will deliver 2.1W into 4Ω. The other package options for the LM4873
will deliver 1.1W into 8Ω. See the Application Information section for
LM4873MTE-1 usage information.

Note 2: An LM4873MTE-1 which has been properly mounted to the circuit
board and forced-air cooled will deliver 2.4W into 3Ω.

Key Specifications

n POat 1% THD+N

into 3Ω (LM4873MTE-1) 2.4W(typ)
into 4Ω (LM4873MTE-1) 2.1W(typ)
into 4Ω (LM4873MTE) 1.9W(typ)
into 8Ω (LM4873) 1.1W(typ)

n Single-ended mode - THD+N

at 75mW into 32Ω

0.5%(max)

n Shutdown current 0.7µA(typ)

Features

n Input mux control and two separate inputs per channel
n Stereo headphone amplifier mode
n “Click and pop” suppression circuitry
n Thermal shutdown protection circuitry
n Exposed-DAP TSSOP and TSSOP packaging available

Applications

n Multimedia monitors
n Portable and desktop computers
n Portable audio systems

Typical Application

Boomer®is a registered trademark of National Semiconductor Corporation.

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*

Refer to the section Proper Selection of External Components, for a detailed discussion of CBsize.

FIGURE 1. Typical Audio Amplifier Application Circuit

April 2000

LM4873 Dual 2.1W Audio Amplifier Plus Stereo Headphone Function

© 2000 National Semiconductor Corporation DS100993 www.national.com

Connection Diagram

Connection Diagram

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Top View

Order Number LM4873MTE-1

See NS Package Number MXA28A for Exposed-DAP TSSOP

DS100993-2

Top View

Order Number LM4873MT, LM4873MTE

See NS Package Number MTC20 for TSSOP

See NS Package Number MXA20A for Exposed-DAP TSSOP

LM4873

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Absolute Maximum Ratings (Note 4)

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 14) Internally limited
ESD Susceptibility (Note 15) 2000V
ESD Susceptibility (Note 16) 200V
Junction Temperature 150˚C
Solder 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 Reliablilty” for other methods of soldering surface

mount devices.

Thermal Resistance

θ

JC

(typ)—M16B 20˚C/W

θ

JA

(typ)—M16B 80˚C/W

θ

JC

(typ)—N16A 20˚C/W

θ

JA

(typ)—N16A 63˚C/W

θ

JC

(typ)—MTC20 20˚C/W

θ

JA

(typ)—MTC20 80˚C/W

θ

JC

(typ)—MXA20A 2˚C/W

θ

JA

(typ)—MXA20A 41˚C/W (Note 5)

θ

JA

(typ)—MXA20A 51˚C/W (Note 6)

θ

JA

(typ)—MXA20A 90˚C/W (Note 7)

θ

JC

(typ)—MXA28A 2˚C/W

θ

JA

(typ)—MXA28A 41˚C/W (Note 8)

θ

JA

(typ)—MXA28A 51˚C/W (Note 9)

θ

JA

(typ)—MXA28A 90˚C/W (Note 10)

Operating Ratings

Temperature Range

T

MIN

≤ TA≤ T

MAX

−40˚C ≤ TA≤ 85˚C

Supply Voltage 2.0V ≤ V

DD

≤ 5.5V

Electrical Characteristics for Entire IC (Notes 3, 4)

The following specifications apply for VDD= 5V unless otherwise noted. Limits apply for TA= 25˚C.

Symbol Parameter Conditions LM4873 Units

(Limits)

Typical Limit

(Note 17) (Note 18)

V

DD

Supply Voltage 2 V (min)

5.5 V (max)

I

DD

Quiescent Power Supply Current VIN= 0V, IO= 0A (Note 19) , HP-IN = 0V 7.5 15 mA (max)

V

IN

= 0V, IO= 0A (Note 19) , HP-IN = 4V 5.8 6 mA (min)

I

SD

Shutdown Current V

PIN1=VDD

0.7 2 µA (min)

V

IH

Headphone High Input Voltage 4 V (min)

V

IL

Headphone Low Input Voltage 0.8 V (max)

Electrical Characteristics for Bridged-Mode Operation (Notes 3, 4)

The following specifications apply for VDD= 5V unless otherwise specified. Limits apply for TA= 25˚C.

Symbol Parameter Conditions LM4873 Units

(Limits)

Typical Limit

(Note

17)

(Note

18)

V

OS

Output Offset Voltage VIN= 0V 5 50 mV (max)

P

O

Output Power (Note 13) THD = 1%, f = 1 kHz

LM4873MTE-1, R

L

=3Ω(Note 11)

2.4 W

LM4873MTE, R

L

=3Ω(Note 11) 2.2 W

LM4873MTE-1, R

L

=4Ω(Note 12) 2.1 W

LM4873MTE, R

L

=4Ω(Note 12) 1.9 W

LM4873, R

L

=8Ω 1.1 1.0 W (min)

THD+N = 10%, f = 1 kHz

LM4873MTE-1, R

L

=3Ω(Note 11) 3.0 W

LM4873MTE-1, R

L

=4Ω(Note 12) 2.6

LM4873, R

L

=8Ω 1.5 W

THD+N = 1%, f = 1 kHz, R

L

=32Ω 0.34 W

LM4873

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Electrical Characteristics for Bridged-Mode Operation (Notes 3, 4) (Continued)

The following specifications apply for VDD= 5V unless otherwise specified. Limits apply for TA= 25˚C.

Symbol Parameter Conditions LM4873 Units

(Limits)

Typical Limit

(Note

17)

(Note

18)

THD+N Total Harmonic Distortion+Noise 20 Hz ≤ f ≤ 20 kHz, A

VD

=2

LM4873MTE-1, R

L

=4Ω,PO=2W

0.3

LM4873, R

L

=8Ω,PO= 1W 0.3 %

PSRR Power Supply Rejection Ratio V

DD

= 5V, V

RIPPLE

= 200 mV

RMS,RL

=8Ω,

C

B

= 1.0 µF

67 dB

X

TALK

Channel Separation f = 1 kHz, CB= 1.0 µF 80 dB

SNR Signal To Noise Ratio V

DD

= 5V, PO= 1.1W, RL=8Ω 97 dB

Electrical Characteristics for Single-Ended Operation (Notes 3, 4)

The following specifications apply for VDD= 5V unless otherwise specified. Limits apply for TA= 25˚C.

Symbol Parameter Conditions LM4873 Units

(Limits)

Typical Limit

(Note

17)

(Note

18)

V

OS

Output Offset Voltage VIN= 0V 5 50 mV (max)

P

O

Output Power THD = 0.5%, f = 1 kHz, RL=32Ω 85 75 mW (min)

THD+N = 1%, f = 1 kHz, R

L

=8Ω 340 mW

THD+N = 10%, f = 1 kHz, R

L

=8Ω 440 mW

THD+N Total Harmonic Distortion+Noise A

V

= −1, PO= 75 mW, 20 Hz ≤ f ≤ 20 kHz,

R

L

=32Ω

0.2 %

PSRR Power Supply Rejection Ratio C

B

= 1.0 µF, V

RIPPLE

= 200 mV

RMS

,

f=1kHz

52 dB

X

TALK

Channel Separation f = 1 kHz, CB= 1.0 µF 60 dB

SNR Signal To Noise Ratio V

DD

= 5V, PO= 340mW, RL=8Ω 94 dB

Note 3: All voltages are measured with respect to the ground pins, 2, 7, and 15, unless otherwise specified.
Note 4: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is func-

tional, but do not guarantee specific performance limits. Electrical Characteristics state DC andAC 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 5: The θ

JA

given is for an MXA20A package whose exposed-DAP is soldered to an exposed 2in2piece of 1 ounce printed circuit board copper.

Note 6: The θ

JA

given is for an MXA20A package whose exposed-DAP is soldered to an exposed 1in2piece of 1 ounce printed circuit board copper.

Note 7: The θ

JA

given is for an MXA20A package whose exposed-DAP is not soldered to any copper.

Note 8: The θ

JA

given is for an MXA28A package whose exposed-DAP is soldered to an exposed 2in2piece of 1 ounce printed circuit board copper.

Note 9: The θ

JA

given is for an MXA28A package whose exposed-DAP is soldered to an exposed 1in2piece of 1 ounce printed circuit board copper.

Note 10: The θ

JA

given is for an MXA28A package whose exposed-DAP is not soldered to any copper.

Note 11: When driving 3Ω loads from a 5V supply, the LM4873MTE or LM4873MTE-1 must be mounted to the circuit board and forced-air cooled (450 linear-feet
per minute).

Note 12: When driving 4Ω loads from a 5V supply, the LM4873MTE or LM4873MTE-1 must be mounted to the circuit board.
Note 13: Output power is measured at the device terminals.
Note 14: The maximum power dissipation must be derated at elevated temperatures and is dictated by T

JMAX

, θJA, and the ambient temperature TA. The maximum

allowable power dissipation is P

DMAX

=(T

JMAX−TA

)/θJA. For the LM4873, T

JMAX

= 150˚C. For the θJAs for different packages, please see the Application Informa-

tion section or the Absolute Maximum Ratings section.

Note 15: Human body model, 100 pF discharged through a 1.5 kΩ resistor.
Note 16: Machine model, 220 pF–240 pF discharged through all pins.
Note 17: Typicals are measured at 25˚C and represent the parametric norm.
Note 18: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).
Note 19: The quiescent power supply current depends on the offset voltage when a practical load is connected to the amplifier.

LM4873

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Truth Table for Logic Inputs

SHUTDOWN HP-IN INPUT

SELECT

LM4873 MODE (INPUT #)

Low Low Low Bridged (1)
Low Low High Bridged (2)
Low High Low Single-Ended (1)
Low High High Single-Ended (2)

High X X Shutdown

LM4873

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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 C

i

at fc= 1/(2πRiCi).

2. C

i

Input coupling capacitor which blocks the DC voltage at the amplifier’s input terminals. Also creates a
highpass filter with R

i

at fc= 1/(2πRiCi). Refer to the section, Proper Selection of External Components,

for an explanation of how to determine the value of C

i

.

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 the Power 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 the section, Proper Selection of
External Components, for information concerning proper placement and selection of C

B

.

Typical Performance Characteristics
MTE (20 pin)Specific Characteristics

Note 20: These curves show the thermal dissipation ability of the LM4873MTE at different ambient temperatures given these conditions:

500LFPM + JEDEC board: The part is soldered to a 1S2P 20-lead exposed-DAP TSSOP test board with 500 linear feet per minute of forced-air flow across

it. Board information - copper dimensions: 74x74mm, copper coverage: 100% (buried layer) and 12% (top/bottom layers), 16 vias under the exposed-DAP.

500LFPM + 2.5in

2

: The part is soldered to a 2.5in2, 1 oz. copper plane with 500 linear feet per minute of forced-air flow across it.

2.5in

2

: The part is soldered to a 2.5in2, 1oz. copper plane.

Not Attached: The part is not soldered down and is not forced-air cooled.

LM4873MTE
THD+N vs Output Power

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LM4873MTE
THD+N vs Frequency

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LM4873MTE
THD+N vs Frequency

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LM4873MTE
Power Dissipation vs Power Output

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LM4873MTE(Note 20)
Power Derating Curve

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LM4873

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