LM4843
Stereo 2W Audio Power Amplifiers
with DC Volume Control
General Description
The LM4843 is a monolithic integrated circuit that provides
DC volume control, and stereo bridged audio power amplifi-
ers capable of producing 2W into 4
(Note 1) with less than
1.0% THD or 2.2W into 3
(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 LM4843 incorporates a
DC volume control with stereo bridged audio power amplifi-
ers making it optimally suited for multimedia monitors, por-
table radios, desktop, and portable computer applications.
The LM4843 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 LM4843MH will
deliver 2W into 4
. See the Application Information section for LM4843MH
usage information.
Note 2: LM4843MH that has been properly mounted to the circuit board and
forced-air cooled will deliver 2.2W into 3
.
Key Specifications
n
P
O
at 1% THD+N
n
into 3
2.2W (typ)
n
into 4
2.0W (typ)
n
into 8
1.1W (typ)
n
Shutdown current
0.7A (typ)
Features
n
Acoustically Enhanced DC Volume Control Taper
n
Stereo bridged power amplifiers
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
Block Diagram
Boomer
is a registered trademark of NationalSemiconductor Corporation.
20038389
FIGURE 1. LM4843 Block Diagram
July 2002
LM4843
Stereo
2W
Audio
Power
Amplifiers
with
DC
V
olume
Control
2002 National Semiconductor Corporation
DS200383
www.national.com
Absolute Maximum Ratings
(Note 10)
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
Internally limited
ESD Susceptibility (Note 12)
2000V
ESD Susceptibility (Note 13)
200V
Junction Temperature
150C
Soldering Information
Small Outline Package
Vapor Phase (60 sec.)
215C
Infrared (15 sec.)
220C
See AN-450 "Surface Mounting and their Effects on
Product Reliability" for other methods of soldering surface
mount devices.
JC
(typ) -- MXA20A
2C/W
JA
(typ) -- MXA20A (exposed
DAP) (Note 4)
41C/W
JA
(typ) -- MXA20A (exposed
DAP) (Note 3)
54C/W
JA
(typ) -- MXA20A (exposed
DAP) (Note 5)
59C/W
JA
(typ) -- MXA20A (exposed
DAP) (Note 6)
93C/W
Operating Ratings
Temperature Range
T
MIN
T
A
T
MAX
-40C
TA 85C
Supply Voltage
2.7V
V
DD
5.5V
Electrical Characteristics for Entire IC
(Notes 7, 10) The following specifications apply for V
DD
= 5V unless otherwise noted. Limits apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM4843
Units
(Limits)
Typical
(Note 14)
Limit
(Note 15)
V
DD
Supply Voltage
2.7
V (min)
5.5
V (max)
I
DD
Quiescent Power Supply Current
V
IN
= 0V, I
O
= 0A
15
30
mA (max)
I
SD
Shutdown Current
V
shutdown
= V
DD
0.7
2.0
A (max)
Electrical Characteristics for Volume Attenuators
(Notes 7, 10) The following specifications apply for V
DD
= 5V. Limits apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM4843
Units
(Limits)
Typical
(Note 14)
Limit
(Note 15)
C
RANGE
Attenuator Range (Note 16)
Attenuation with V
DCVol
= 5V, No Load
0.75
dB (max)
Attenuation with V
DCVol
= 0V
-75
dB (min)
A
M
Mute Attenuation
V
mute
= 5V, Bridged Mode (BM)
-78
dB (min)
LM4843
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3
Electrical Characteristics for Bridged Mode Operation
(Notes 7, 10) The following specifications apply for V
DD
= 5V, unless otherwise noted. Limits apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM4843
Units
(Limits)
Typical
(Note 14)
Limit
(Note 15)
V
OS
Output Offset Voltage
V
IN
= 0V, No Load
10
50
mV (max)
P
O
Output Power
THD + N = 1.0%; f=1kHz; R
L
= 3
(Note 8)
2.2
W
THD + N = 1.0%; f=1kHz; R
L
= 4
(Note 9)
2
W
THD = 1% (max);f = 1 kHz;
R
L
= 8
1.1
1.0
W (min)
THD+N = 10%;f = 1 kHz; R
L
= 8
1.5
W
THD+N
Total Harmonic Distortion+Noise
P
O
= 1W, 20 Hz
<
f
<
20 kHz,
R
L
= 8
, A
VD
= 2
0.3
%
P
O
= 340 mW, R
L
= 32
1.0
%
PSRR
Power Supply Rejection Ratio
C
B
= 1.0 F, f = 120 Hz,
V
RIPPLE
= 200 mVrms; R
L
= 8
74
dB
SNR
Signal to Noise Ratio
V
DD
= 5V, P
OUT
= 1.1W, R
L
= 8
,
A-Wtd Filter
93
dB
X
talk
Channel Separation
f=1kHz, C
B
= 1.0 F
70
dB
Note 3: The
JA
given is for an MXA20A package whose exposed-DAP is soldered to an exposed 2in
2
piece of 1 ounce printed circuit board copper.
Note 4: The
JA
given is for an MXA20A package whose exposed-DAP is soldered to a 2in
2
piece of 1 ounce printed circuit board copper on a bottom side layer
through 21 8mil vias.
Note 5: The
JA
given is for an MXA20A package whose exposed-DAP is soldered to an exposed 1in
2
piece of 1 ounce printed circuit board copper.
Note 6: The
JA
given is for an MXA20A package whose exposed-DAP is not soldered to any copper.
Note 7: All voltages are measured with respect to the ground pins, unless otherwise specified. All specifications are tested using the typical application as shown
in Figure 1.
Note 8: When driving 3
loads from a 5V supply the LM4843MH must be mounted to the circuit board and forced-air cooled.
Note 9: When driving 4
loads from a 5V supply the LM4843MH must be mounted to the circuit board.
Note 10: 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 is within the Operating Ratings. Marshall Chiu feels there are better ways to obtain 'More
Wattage in the Cottage.' Specifications are not guaranteed for parameters where no limit is given, however, the typical value is a good indication of device
performance.
Note 11: 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 LM4843MH, T
JMAX
= 150C, and the typical junction-to-ambient thermal resistance, when board
mounted, is 80C/W for the MHC20 package.
Note 12: Human body model, 100 pF discharged through a 1.5 k
resistor.
Note 13: Machine Model, 220 pF240 pF discharged through all pins.
Note 14: Typicals are measured at 25C and represent the parametric norm.
Note 15: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level). Datasheet min/max specification limits are guaranteed by design, test, or
statistical analysis.
Note 16: Refers only to the internal Volume Attenuation steps. Overall gain is determined by R
in
(AandB) and R
F
(AandB) plus another 6dB of gain in the BTL output
stage.
LM4843
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