LM4835
Stereo 2W Audio Power Amplifiers
with DC Volume Control and Selectable Gain
General Description
The LM4835 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 LM4835 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 LM4835 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 LM4835MTE will
deliver 2W into 4
. The LM4835MT will deliver 1.1W into 8
. See the Appli-
cation Information section for LM4835MTE usage information.
Note 2: An LM4835MTE which 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
into 3
(LM4835MTE)
2.2W(typ)
into 4
(LM4835MTE)
2.0W(typ)
into 8
(LM4835)
1.1W(typ)
n
Single-ended mode - THD+N
at 85mW into 32
1.0%(typ)
n
Shutdown current
0.7A(typ)
Features
n
PC98 Compliant
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
configurable
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
Connection Diagram
Boomer
is a registered trademark of NationalSemiconductor Corporation.
DS100139-1
FIGURE 1. LM4835 Block Diagram
TSSOP Package
DS100139-2
Top View
Order Number LM4835MT
See NS Package Number MTC28 for TSSOP
Order Number LM4835MTE
See NS Package Number MXA28A for Exposed DAP
TSSOP
March 1999
LM4835
Stereo
2W
Audio
Power
Amplifiers
with
DC
V
olume
Control
and
Selectable
Gain
1999 National Semiconductor Corporation
DS100139
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) -- 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
LM4835
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
pin 2
= 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
LM4835
Units
(Limits)
Typical
(Note 14)
Limit
(Note 15)
C
RANGE
Attenuator Range
Gain with V
pin 7
= 5V
0
0.5
dB (max)
Attenuation with V
pin 7
= 0V
-81
-80
dB (min)
A
M
Mute Attenuation
V
pin 5
= 5V, Bridged Mode
-88
-80
dB (min)
V
pin 5
= 5V, Single-Ended Mode
-88
-80
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
LM4835
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
THD+N
Total Harmonic Distortion+Noise
V
OUT
= 1V
RMS
, f=1kHz, R
L
= 10k
,
A
VD
= 1
0.065
%
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2
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
LM4835
Units
(Limits)
Typical
(Note 14)
Limit
(Note 15)
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
LM4835
Units
(Limits)
Typical
(Note 14)
Limit
(Note 15)
V
OS
Output Offset Voltage
V
IN
= 0V
5
30
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 = 0.5% (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 LM4835MTE must be mounted to the circuit board and forced-air cooled.
Note 9: When driving 4
loads from a 5V supply the LM4835MTE 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 Watt-
age 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 LM4835MT, T
JMAX
= 150C, and the typical junction-to-ambient thermal resistance, when board
mounted, is 80C/W assuming the MTC28 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).
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3
Typical Application
Truth Table for Logic Inputs
(Note 16)
Mute
Mode
HP Sense
DC Vol. Control
Bridged Output
Single-Ended Output
0
0
0
Fixed Level
Vol. Fixed
_
0
0
1
Fixed Level
Muted
Vol. Fixed
0
1
0
Adjustable
Vol. Changes
_
0
1
1
Adjustable
Muted
Vol. Changes
1
X
X
_
Muted
Muted
Note 16: If system beep is detected on the Beep In pin (pin 11), the system beep will be passed through the bridged amplifier regardless of the logic of the Mute
and HP sense pins.
DS100139-3
FIGURE 2. Typical Application Circuit
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4
Typical Performance Characteristics
MTE Specific Characteristics
Note 17: These curves show the thermal dissipation ability of the LM4835MTE 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.
Non-MTE Specific Characteristics
LM4835MTE
THD+N vs Output Power
DS100139-70
LM4835MTE
THD+N vs Frequency
DS100139-71
LM4835MTE
THD+N vs Output Power
DS100139-72
LM4835MTE
THD+N vs Frequency
DS100139-73
LM4835MTE
Power Dissipation vs Output Power
DS100139-65
LM4835MTE(Note 17)
Power Derating Curve
DS100139-64
THD+N vs Frequency
DS100139-57
THD+N vs Frequency
DS100139-58
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