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LM4873 Dual 2.1W Audio Amplifier Plus Stereo Headphone Function
October 2002
LM4873
Dual 2.1W Audio Amplifier Plus Stereo Headphone
Function
General Description
The LM4873 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. In addition, the headphone input pin
allows the amplifiers to operate in single-ended mode when
driving stereo headphones. A MUX control pin allows selec-
tion between the two stereo sets of amplifier inputs. The
MUX control can also be used to select two different
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 sim-
plify 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 cir-
cuitry to reduce “clicks and pops” during device turn-on.
Note 1:
An LM4873MTE-1, LM4873MTE, or LM4873LQ that has been
properly mounted to a circuit board will deliver 2.1W into 4Ω. The other
package options for the LM4873 will deliver 1.1W into 8Ω. See the Applica-
tion Information sections for further information concerning the
LM4873MTE-1, LM4873MTE, and the LM4873LQ.
Note 2:
An LM4873MTE-1, LM4873MTE, or LM4873LQ that has been prop-
erly mounted to a circuit board and forced-air cooled will deliver 2.4W into 3Ω.
Key Specifications
j
P
O
at 1% THD+N
LM4873LQ, 3Ω, 4Ω loads
LM4873IBL, 8Ω load
LM4873MTE, 4Ω
LM4873, 8Ω
j
Single-ended mode THD+N
2.4W(typ), 2.1W(typ)
1.1W(typ)
1.9W(typ)
1.1W(typ)
0.5%(max)
0.7µA(typ)
2V to 5.5V
LM4873MTE-1, 3Ω, 4Ω loads 2.4W(typ), 2.1W(typ)
at 75mW into 32Ω
j
Shutdown current
j
Supply voltage range
Features
Input mux control and two separate inputs per channel
Stereo headphone amplifier mode
“Click and pop” suppression circuitry
Thermal shutdown protection circuitry
PCB area-saving micro SMD and thin micro SMD
packages
n
TSSOP and exposed-DAP TSSOP and LLP packages
n
n
n
n
n
Applications
n
Multimedia monitors
n
Portable and desktop computers
n
Portable audio systems
Connection Diagrams
10099330
10099302
Top View
Order Number LM4873MTE-1
See NS Package Number MXA28A for Exposed-DAP
TSSOP
Top View
Order Number LM4873MT, LM4873MTE
See NS Package Number MTC20 for TSSOP
See NS Package Number MXA20A for Exposed-DAP
TSSOP
Boomer
®
is a registered trademark of National Semiconductor Corporation.
© 2002 National Semiconductor Corporation
DS100993
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LM4873
Connection Diagrams
(Continued)
10099353
Top View
(Bump-side down)
Order Number LM4873IBL, LM4873ITL
See NS Package Number BLA20AAB for micro SMD
See NS Package Number TLA20AAA
10099338
Top View
Order Number LM4873LQ
See NS Package Number LQA24A for Exposed-DAP LLP
micro SMD Marking
10099357
10099328
Top View
XY - Date Code
TT - Die Traceability
G - Boomer Family
I - LM4873IBL
Top View
XY - Date Code
TT - Die Traceability
G - Boomer Family
B2 - LM4873ITL
LM4873IBP Pin Designations
Pin (Bump) Number
A1
A2
A3
A4
B1
B2
B3
B4
C1
C2
Pin (Bump) Function
-IN A
1
-IN A
2
-IN B
2
-IN B
1
-OUT A
GND
GND
-OUT B
+IN A
V
DD
Pin (Bump) Number
C3
C4
D1
D2
D3
D4
E1
E2
E3
E4
Pin (Bump) Function
V
DD
+IN B
+OUT A
GND
GND
+OUT B
MUX CTRL
SHUTDOWN
HP-IN
BYPASS
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2
LM4873
Typical Application
10099331
Note: Pin out shown for the 28-pin Exposed-DAP TSSOP package. Refer to the Connection Diagrams for the pin out of the 20-pin Exposed-DAP TSSOP,
Exposed-DAP LLP, and micro SMD packages.
3
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LM4873
Absolute Maximum Ratings
(Note 3)
θ
JC
(typ) — MTC20
θ
JA
(typ) — MTC20
θ
JC
(typ) — MXA20A
θ
JA
(typ) — MXA20A
θ
JA
(typ) — MXA20A
θ
JA
(typ) — MXA20A
θ
JC
(typ) — MXA28A
θ
JA
(typ) — MXA28A
θ
JA
(typ) — MXA28A
θ
JA
(typ) — MXA28A
θ
JC
(typ) — LQA24A
θ
JA
(typ) — LQA24A
θ
JA
(typ) — micro SMD
20˚C/W
80˚C/W
2˚C/W
41˚C/W (Note 7)
51˚C/W (Note 8)
90˚C/W (Note 9)
2˚C/W
41˚C/W (Note 10)
51˚C/W (Note 11)
90˚C/W (Note 12)
3.0˚C/W
42˚C/W (Note 13)
60˚C/W (Note 14)
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)
ESD Susceptibility (Note 6)
Junction Temperature
Solder Information
Small Outline Package
Vapor Phase (60 sec.)
Infrared (15 sec.)
215˚C
220˚C
6.0V
−65˚C to +150˚C
−0.3V to V
DD
+0.3V
Internally limited
2000V
200V
150˚C
Operating Ratings
Temperature Range
T
MIN
≤
T
A
≤
T
MAX
Supply Voltage
−40˚C
≤
T
A
≤
85˚C
2.0V
≤
V
DD
≤
5.5V
See AN-450 “Surface Mounting and their Effects on
Product Reliablilty” for other methods of soldering
surface mount devices.
Thermal Resistance
Electrical Characteristics
(Notes 3, 15)
The following specifications apply for V
DD
= 5V unless otherwise noted. Limits apply for T
A
= 25˚C.
Symbol
Parameter
Conditions
LM4873
Typical
(Note 16)
V
DD
I
DD
I
SD
V
IH
V
IL
Supply Voltage
Quiescent Power Supply Current
Shutdown Current
Headphone High Input Voltage
Headphone Low Input Voltage
V
IN
= 0V, I
O
= 0A (Note 18) , HP-IN = 0V
V
IN
= 0V, I
O
= 0A (Note 18) , HP-IN = 4V
V
DD
applied to the SHUTDOWN pin
7.5
5.8
0.7
Limit
(Note 17)
2
5.5
15
6
2
4
0.8
V (min)
V (max)
mA (max)
mA (min)
µA (max)
V (min)
V (max)
Units
(Limits)
Electrical Characteristics for Bridged-Mode Operation
(Notes 3, 15)
The following specifications apply for V
DD
= 5V unless otherwise specified. Limits apply for T
A
= 25˚C.
Symbol
Parameter
Conditions
LM4873
Typical
V
OS
P
O
Output Offset Voltage
Output Power (Note 19)
V
IN
= 0V
THD+N = 1%, f = 1kHz (Note 20)
LM4873MTE-1, R
L
= 3Ω
LM4873MTE, R
L
= 3Ω
LM4873LQ, R
L
= 3Ω
LM4873MTE-1, R
L
= 4Ω
LM4873MTE, R
L
= 4Ω
LM4873LQ, R
L
= 4Ω
LM4873MT, R
L
= 4Ω
LM4873, R
L
= 8Ω
2.4
2.2
2.2
2.1
1.9
1.9
1.9
1.1
1.0
W
W
W
W
W
W
W
W (min)
5
Limit
50
(Note 16) (Note 17)
mV (max)
Units
(Limits)
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