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 4
load (Note 1) or 2.4W to a 3 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 4
. The other
package options for the LM4873 will deliver 1.1W into 8
. 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 3
.
Key Specifications
j
P
O
at 1% THD+N
LM4873LQ, 3
, 4 loads
2.4W(typ), 2.1W(typ)
LM4873MTE-1, 3
, 4 loads 2.4W(typ), 2.1W(typ)
LM4873IBL, 8
load
1.1W(typ)
LM4873MTE, 4
1.9W(typ)
LM4873, 8
1.1W(typ)
j
Single-ended mode THD+N
at 75mW into 32
0.5%(max)
j
Shutdown current
0.7A(typ)
j
Supply voltage range
2V to 5.5V
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
PCB area-saving micro SMD and thin micro SMD
packages
n
TSSOP and exposed-DAP TSSOP and LLP packages
Applications
n
Multimedia monitors
n
Portable and desktop computers
n
Portable audio systems
Connection Diagrams
10099330
Top View
Order Number LM4873MTE-1
See NS Package Number MXA28A for Exposed-DAP
TSSOP
10099302
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.
October 2002
LM4873
Dual
2.1W
Audio
Amplifier
Plus
Stereo
Headphone
Function
2002 National Semiconductor Corporation
DS100993
www.national.com
Absolute Maximum Ratings
(Note 3)
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
-65C to +150C
Input Voltage
-0.3V to V
DD
+0.3V
Power Dissipation (Note 4)
Internally limited
ESD Susceptibility (Note 5)
2000V
ESD Susceptibility (Note 6)
200V
Junction Temperature
150C
Solder Information
Small Outline Package
Vapor Phase (60 sec.)
215C
Infrared (15 sec.)
220C
See AN-450 "Surface Mounting and their Effects on
Product Reliablilty" for other methods of soldering
surface mount devices.
Thermal Resistance
JC
(typ) -- MTC20
20C/W
JA
(typ) -- MTC20
80C/W
JC
(typ) -- MXA20A
2C/W
JA
(typ) -- MXA20A
41C/W (Note 7)
JA
(typ) -- MXA20A
51C/W (Note 8)
JA
(typ) -- MXA20A
90C/W (Note 9)
JC
(typ) -- MXA28A
2C/W
JA
(typ) -- MXA28A
41C/W (Note 10)
JA
(typ) -- MXA28A
51C/W (Note 11)
JA
(typ) -- MXA28A
90C/W (Note 12)
JC
(typ) -- LQA24A
3.0C/W
JA
(typ) -- LQA24A
42C/W (Note 13)
JA
(typ) -- micro SMD
60C/W (Note 14)
Operating Ratings
Temperature Range
T
MIN
T
A
T
MAX
-40C
T
A
85C
Supply Voltage
2.0V
V
DD
5.5V
Electrical Characteristics
(Notes 3, 15)
The following specifications apply for V
DD
= 5V unless otherwise noted. Limits apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM4873
Units
(Limits)
Typical
Limit
(Note 16)
(Note 17)
V
DD
Supply Voltage
2
V (min)
5.5
V (max)
I
DD
Quiescent Power Supply Current
V
IN
= 0V, I
O
= 0A (Note 18) , HP-IN = 0V
7.5
15
mA (max)
V
IN
= 0V, I
O
= 0A (Note 18) , HP-IN = 4V
5.8
6
mA (min)
I
SD
Shutdown Current
V
DD
applied to the SHUTDOWN pin
0.7
2
A (max)
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, 15)
The following specifications apply for V
DD
= 5V unless otherwise specified. Limits apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM4873
Units
(Limits)
Typical
Limit
(Note 16)
(Note 17)
V
OS
Output Offset Voltage
V
IN
= 0V
5
50
mV (max)
P
O
Output Power (Note 19)
THD+N = 1%, f = 1kHz (Note 20)
LM4873MTE-1, R
L
= 3
2.4
W
LM4873MTE, R
L
= 3
2.2
W
LM4873LQ, R
L
= 3
2.2
W
LM4873MTE-1, R
L
= 4
2.1
W
LM4873MTE, R
L
= 4
1.9
W
LM4873LQ, R
L
= 4
1.9
W
LM4873MT, R
L
= 4
1.9
W
LM4873, R
L
= 8
1.1
1.0
W (min)
LM4873
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4
Electrical Characteristics for Bridged-Mode Operation
(Notes 3, 15) (Continued)
The following specifications apply for V
DD
= 5V unless otherwise specified. Limits apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM4873
Units
(Limits)
Typical
Limit
(Note 16)
(Note 17)
THD+N = 10%, f = 1kHz (Note 20)
LM4873MTE-1, R
L
= 3
3.0
W
LM4873LQ, R
L
= 3
3.0
W
LM4873MTE-1, R
L
= 4
2.6
W
LM4873LQ, R
L
= 4
2.6
W
LM4873, R
L
= 8
1.5
W
THD+N = 1%, f = 1kHz, R
L
= 32
0.34
W
THD+N
Total Harmonic Distortion+Noise
20Hz
f 20kHz, A
VD
= 2
LM4873MTE-1, R
L
= 4
, P
O
= 2W
0.3
LM4873LQ, R
L
= 4
, P
O
= 2W
LM4873, R
L
= 8
, P
O
= 1W
0.3
%
PSRR
Power Supply Rejection Ratio
V
DD
= 5V, V
RIPPLE
= 200mV
RMS
, R
L
= 8
,
C
B
= 1.0F
67
dB
X
TALK
Channel Separation
f = 1kHz, C
B
= 1.0F
80
dB
SNR
Signal To Noise Ratio
V
DD
= 5V, P
O
= 1.1W, R
L
= 8
97
dB
Electrical Characteristics for Single-Ended Operation
(Notes 3, 15)
The following specifications apply for V
DD
= 5V unless otherwise specified. Limits apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM4873
Units
(Limits)
Typical
Limit
(Note 16)
(Note 17)
V
OS
Output Offset Voltage
V
IN
= 0V
5
50
mV (max)
P
O
Output Power
THD+N = 0.5%, f = 1 kHz, R
L
= 32
85
75
mW (min)
THD+N = 1%, f = 1 kHz, R
L
= 8
340
mW
THD+N = 10%, f = 1 kHz, R
L
= 8
440
mW
THD+N
Total Harmonic Distortion+Noise
A
V
= -1, P
O
= 75mW, 20Hz
f 20kHz,
R
L
= 32
0.2
%
PSRR
Power Supply Rejection Ratio
C
B
= 1.0F, V
RIPPLE
= 200mV
RMS
,
f = 1kHz
52
dB
X
TALK
Channel Separation
f = 1kHz, C
B
= 1.0F
60
dB
SNR
Signal To Noise Ratio
V
DD
= 5V, P
O
= 340mW, R
L
= 8
94
dB
Note 3: 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 operates within the Operating Ratings. Specifications are not guaranteed for parameters where
no limit is given. The typical value however, is a good indication of device performance.
Note 4: The maximum power dissipation must be derated at elevated temperatures and is dictated by T
JMAX
,
JA
, and the ambient temperature T
A
. The maximum
allowable power dissipation is P
DMAX
= (T
JMAX
- T
A
)/
JA
. For the LM4873, T
JMAX
= 150C. For the
JA
s for different packages, please see the Application
Information section or the Absolute Maximum Ratings section.
Note 5: Human body model, 100 pF discharged through a 1.5 k
resistor.
Note 6: Machine model, 220 pF240 pF discharged through all pins.
Note 7: The given
JA
is for an LM4873 packaged in an MXA20A with the Exposed-DAP soldered to an exposed 2in
2
area of 1oz printed circuit board copper.
Note 8: The given
JA
is for an LM4873 packaged in an MXA20A with the Exposed-DAP soldered to an exposed 1in
2
area of 1oz printed circuit board copper.
Note 9: The given
JA
is for an LM4873 packaged in an MXA20A with the Exposed-DAP not soldered to printed circuit board copper.
Note 10: The given
JA
is for an LM4873 packaged in an MXA28A with the Exposed-DAP soldered to an exposed 2in
2
area of 1oz printed circuit board copper.
Note 11: The given
JA
is for an LM4873 packaged in an MXA28A with the Exposed-DAP soldered to an exposed 1in
2
area of 1oz printed circuit board copper.
Note 12: The given
JA
is for an LM4873 packaged in an MXA28A with the Exposed-DAP not soldered to printed circuit board copper.
Note 13: The given
JA
is for an LM4873 packaged in an LQA24A with the Exposed-DAP soldered to an exposed 2in
2
area of 1oz printed circuit board copper.
Note 14: The
JA
is specified for an LM4873 packaged in a BLA20AAB or TLA20AAA with their four ground connections soldered to a 3in
2
, 1oz copper plane.
Note 15: All voltages are measured with respect to the ground (GND) pins, unless otherwise specified.
Note 16: Typicals are specified at 25C and represent the parametric norm.
Note 17: Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis.
LM4873
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