LM4840
Stereo 2W Audio Power Amplifiers
with Digital Volume Control and Input Mux
General Description
The LM4840 is a monolithic integrated circuit that provides
digital volume control and stereo bridged audio power am-
plifiers 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 LM4840 incorporates a
digital volume control, stereo bridged audio power amplifiers,
an input mux, and a last volume level memory function to
save the volume setting during shutdown. These features
make it optimally suited for multimedia monitors, portable
radios, desktop, and portable computer applications.
The LM4840 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 LM4840LQ and
LM4840MH will deliver 2W into 4
. The LM4840MT will deliver 1.1W into 8
.
See the Application Information section LM4840LQ and for LM4840MH us-
age information.
Note 2: An LM4840LQ and LM4840MH 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
(LM4840LQ, LM4840MH)
2.2W (typ)
n
into 4
(LM4840LQ, LM4840MH)
2.0W (typ)
n
into 8
(LM4840)
1.1W (typ)
n
Single-ended mode - THD+N at 85mW into 32
1.0%
(typ)
n
Shutdown current
0.2A (typ)
Features
n
PC98 and PC99 Compliant
n
Digital Volume Control Interface
n
System Beep Detect
n
Stereo switchable bridged/single-ended power amplifiers
n
"Click and pop" suppression circuitry
n
Thermal shutdown protection circuitry
n
Input Mux
n
Capless headphone drivers
n
Last volume memory from shutdown
Applications
n
Portable and Desktop Computers
n
Multimedia Monitors
n
Portable Radios, PDAs, and Portable TVs
Connection Diagram
Boomer
is a registered trademark of NationalSemiconductor Corporation.
LLP Package
DS200104-35
Top View
Order Number LM4840LQ
See NS Package Number LQA028A for Exposed-DAP LLP
December 2001
LM4840
Stereo
2W
Audio
Power
Amplifiers
with
Digital
V
olume
Control
and
Input
Mux
2001 National Semiconductor Corporation
DS200104
www.national.com
Connection Diagram
(Continued)
Block Diagram
TSSOP Package
DS200104-2
Top View
Order Number LM4840MT
See NS Package Number MTC28 for TSSOP
Order Number LM4840MH
See NS Package Number MXA28A for Exposed-DAP TSSOP
DS200104-1
FIGURE 1. LM4840 Block Diagram
LM4840
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2
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.
See AN-1187 "Leadless Leadframe Package" for
detailed information on usage of LLP devices.
JC
(typ) -- LQA028A (Note
16)
3C/W
JA
(typ) -- LQA028A (Note
16)
42C/W
JC
(typ) -- MTC28
20C/W
JA
(typ) -- MTC28
80C/W
JC
(typ) -- MXA28A
2C/W
JA
(typ) -- MXA28A (Note 4)
41C/W
JA
(typ) -- MXA28A (Note 3)
54C/W
JA
(typ) -- MXA28A (Note 5)
59C/W
JA
(typ) -- MXA28A (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
LM4840
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
12
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
LM4840
Units
(Limits)
Typical
(Note 14)
Limit
(Note 15)
C
RANGE
Attenuator Range
Gain with Digital Volume Max
0
0.5
dB (max)
Attenuation with Digital Volume Min
-81
-75
dB (min)
A
M
Mute Attenuation
V
MUTE
= V
DD
, Bridged Mode
-88
-78
dB (min)
V
MUTE
= V
DD
, Single-Ended Mode
-88
-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
LM4840
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
LM4840
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3
Electrical Characteristics for Single-Ended Mode Operation
(Continued)
(Notes 7, 10)
The following specifications apply for V
DD
= 5V. Limits apply for T
A
= 25C.
Symbol
Parameter
Conditions
LM4840
Units
(Limits)
Typical
(Note 14)
Limit
(Note 15)
THD+N
Total Harmonic Distortion+Noise
V
OUT
= 1V
RMS
, f=1kHz, R
L
= 10k
,
A
VD
= 1
0.065
%
PSRR
Power Supply Rejection Ratio
C
B
= 1.0 F, f =120 Hz,
V
RIPPLE
= 200 mVrms
58
dB
SNR
Signal to Noise Ratio
P
OUT
=75 mW, R
L
= 32
, A-Wtd
Filter
102
dB
X
talk
Channel Separation
f=1kHz, C
B
= 1.0 F
65
dB
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
LM4840
Units
(Limits)
Typical
(Note 14)
Limit
(Note 15)
V
OS
Output Offset Voltage
V
IN
= 0V, No Load
5
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 = 1.5% (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 MXA28A 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 MXA28A 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 MXA28A 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 MXA28A 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 LM4840LQ and LM4840MH must be mounted to the circuit board and forced-air cooled.
Note 9: When driving 4
loads from a 5V supply the LM4840LQ and LM4840MH 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 LM4840LQ and LM4840MT, T
JMAX
= 150C, and the typical junction-to-ambient thermal
resistance, when board mounted, is 80C/W for the MTC28 package and 42C/W for the LM4840LQ 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 specified at 25C and represent the parametric norm.
Note 15: Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis.
Note 16: Number given is for an LQA028A package whose exposed-DAP is soldered to an exposed 2.5in
2
piece of 1 ounce PCB copper.
LM4840
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4
MH and LQ Specific Characteristics
Note 17: These curves show the thermal dissipation ability of the LM4840MH at different ambient temperatures given these conditions:
500LFPM + 2in
2
: The part is soldered to a 2in
2
, 1 oz. copper plane with 500 linear feet per minute of forced-air flow across it.
2in
2
on bottom: The part is soldered to a 2in
2
, 1oz. copper plane that is on the bottom side of the PC board through 21 8 mil vias.
2in
2
: The part is soldered to a 2in
2
, 1oz. copper plane.
1in
2
: The part is soldered to a 1in
2
, 1oz. copper plane.
Not Attached: The part is not soldered down and is not forced-air cooled.
Typical Performance Characteristics
LM4840MH, LM4840LQ
THD+N vs Output Power
DS200104-70
LM4840MH, LM4840LQ
THD+N vs Frequency
DS200104-71
LM4840MH, LM4840LQ
THD+N vs Output Power
DS200104-72
LM4840MH, LM4840LQ
THD+N vs Frequency
DS200104-73
LM4840MH, LM4840LQ
Power Dissipation vs Output Power
DS200104-65
LM4840MH(Note 17)
Power Derating Curve
DS200104-64
THD+N vs Frequency
DS200104-57
THD+N vs Frequency
DS200104-58
THD+N vs Frequency
DS200104-14
LM4840
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