LM4838
Stereo 2W Audio Power Amplifiers
with DC Volume Control and Selectable Gain
General Description
The LM4838 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 LM4838 incorporates a
DC volume control, stereo bridged audio power amplifiers
and a selectable gain or bass boost, making it optimally
suited for multimedia monitors, portable radios, desktop, and
portable computer applications.
The LM4838 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 LM4838LQ,
LM4838MTE, and LM4838GR will deliver 2W into 4
. The LM4838MT and
LM4838ITL will deliver 1.1W into 8
. See Application Information section
Exposed-DAP package PCB Mounting Considerations for more informa-
tion.
Note 2: An LM4838LQ and LM4838MTE that have 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
(LQ & MTE)
2.2W (typ)
n
into 4
(LQ, MTE, GR)
2.0W (typ)
n
into 8
(MT, MTE, ITL, LQ, & GR)
1.1W (typ)
n
Single-ended mode - THD+N at 85mW into
32
1.0%(typ)
n
Shutdown current
0.7A (typ)
Features
n
DC Volume Control Interface
n
System Beep Detect
n
Stereo switchable bridged/single-ended power amplifiers
n
Selectable internal/external gain and bass boost
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.
20013301
FIGURE 1. LM4838 Block Diagram
November 2004
LM4838
Stereo
2W
Audio
Power
Amplifiers
with
DC
V
olume
Control
and
Selectable
Gain
2004 National Semiconductor Corporation
DS200133
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 (Note 11)
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) -- LQA028AA
3C/W
JA
(typ) -- LQA028AA
42C/W
JC
(typ) -- MTC28
20C/W
JA
(typ) -- MTC28
80C/W
JC
(typ) -- MXA28A
2C/W
JA
(typ) -- MXA28A (exposed
DAP) (Note 4)
41C/W
JA
(typ) -- MXA28A (exposed
DAP) (Note 3)
54C/W
JA
(typ) -- MXA28A (exposed
DAP) (Note 5)
59C/W
JA
(typ) -- MXA28A (exposed
DAP) (Note 6)
93C/W
JA
(typ) -- ITL36AAA
100C/W
JC
(typ) -- ITL36AAA (Note 16)
65C/W
JA
(typ) -- GRA49A
100C/W
JC
(typ) -- GRA49A (Note 17)
54C/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
LM4838
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)
V
IH
Headphone Sense High Input Voltage
4
V (min)
V
IL
Headphone Sense Low Input Voltage
0.8
V (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
LM4838
Units
(Limits)
Typical
(Note 14)
Limit
(Note 15)
C
RANGE
Attenuator Range
Gain with V
DCVol
= 5V, No Load
0.75
dB (max)
Attenuation with V
DCVol
= 0V (BM &
SE)
-75
dB (min)
A
M
Mute Attenuation
V
mute
= 5V, Bridged Mode (BM)
-78
dB (min)
V
mute
= 5V, Single-Ended Mode (SE)
-78
dB (min)
Electrical Characteristics for Single-Ended Mode Operation
(Notes 7, 10)
The following specifications apply for V
DD
= 5V. Limits apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM4838
Units
(Limits)
Typical
(Note 14)
Limit
(Note 15)
P
O
Output Power
THD = 1.0%; f = 1kHz; R
L
= 32
85
mW
THD = 10%; f = 1 kHz; R
L
= 32
95
mW
LM4838
www.national.com
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