LM4810
Dual 105mW Headphone Amplifier with Active-High
Shutdown Mode
General Description
The LM4810 is a dual audio power amplifier capable of
delivering 105mW per channel of continuous average power
into a 16
load with 0.1% (THD+N) from a 5V power supply.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. Since the LM4810 does not require
bootstrap capacitors or snubber networks, it is optimally
suited for low-power portable systems.
The unity-gain stable LM4810 can be configured by external
gain-setting resistors.
The LM4810 features an externally controlled, active-high,
micropower consumption shutdown mode, as well as an
internal thermal shutdown protection mechanism.
Key Specifications
n
THD+N at 1kHz, 105mW continuous average power into
16
0.1% (typ)
n
THD+N at 1kHz, 70mW continuous average power into
32
0.1% (typ)
n
Shutdown Current
0.4A (typ)
Features
n
Active-high shutdown mode
n
LLP, MSOP, and SO surface mount packaging
n
"Click and Pop" suppression circuitry
n
Low shutdown current
n
No bootstrap capacitors required
n
Unity-gain stable
Applications
n
Cellular Phones
n
Personal Computers
n
Microphone Preamplifier
n
PDA's
Typical Application
Boomer
is a registered trademark of National Semiconductor Corporation.
20008901
*Refer to the Application Information Section for information concerning proper selection of the input and output coupling capacitors.
FIGURE 1. Typical Audio Amplifier Application Circuit
November 2002
LM4810
Dual
105mW
Headphone
Amplifier
with
Active-High
Shutdown
Mode
2002 National Semiconductor Corporation
DS200089
www.national.com
Connection Diagrams
MSOP Package
SO Package
20008902
Top View
Order NumberLM4810MM
See NS Package Number MUA08A
20008902
Top View
Order NumberLM4810MA
See NS Package Number M08A
LLP Package
MSOP Marking
20008986
Top View
Order NumberLM4810LD
See NS Package Number LDA08B
20008991
SO Marking
LLP Marking
20008992
20008993
LM4810
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2
Absolute Maximum Ratings
(Note 2)
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
ESD Susceptibility (Note 4)
3.5kV
ESD Machine Model (Note 8)
250V
Junction Temperature (T
J
)
150C
Soldering Information (Note 1)
Small Outline Package
Vapor Phase (60 sec.)
215C
Infrared (15 sec.)
220C
Thermal Resistance
JA
(SO)
170C/W
JC
(SO)
35C/W
JA
(MSOP)
210C/W
JC
(MSOP)
56C/W
JA
(LLP)
117C/W (Note 9)
JA
(LLP)
150C/W (Note 10)
JC
(LLP)
15C/W
Operating Ratings
(Note 2)
Temperature Range
T
MIN
T
A
T
MAX
-40C
T
A
85C
Supply Voltage (V
CC
2.0V
V
CC
5.5V
Note 1: See AN-450 "Surface Mounting and their Effects on Product Reli-
ability" for other methods of soldering surface mount devices.
Electrical Characteristics
(Notes 2, 3)
The following specifications apply for V
DD
= 5V unless otherwise specified, limits apply to T
A
= 25C.
Symbol
Parameter
Conditions
LM4810
Units
(Limits)
Typ
(Note 5)
Limit
(Note 7)
V
DD
Supply Voltage
2.0
V (min)
5.5
V (max)
I
DD
Supply Current
V
IN
= 0V, I
O
= 0A
1.3
3
mA(max)
I
SD
Shutdown Current
V
IN
= 0V, V
SHUTDOWN
= V
DD
0.4
2
A(max)
V
OS
Output Offset Voltage
V
IN
= 0V
4.0
50
mV(max)
P
O
Output Power
THD+N = 0.1%, f = 1kHz
R
L
= 16
105
mW
R
L
= 32
70
65
mW(min)
THD+N
Total Harmonic Distortion
P
O
= 50mW, R
L
= 32
f = 20Hz to 20kHz
0.3
%
Crosstalk
Channel Separation
R
L
= 32
; P
O
= 70mW
70
dB
PSRR
Power Supply Rejection Ratio
C
B
= 1.0F; V
RIPPLE
= 200mV
PP
,
f = 1kHz; Input terminated into 50
70
dB
V
SDIH
Shutdown Voltage Input High
0.8 x V
DD
V (min)
V
SDIL
Shutdown Voltage Input Low
0.2 x V
DD
V (max)
Electrical Characteristics
(Notes 2, 3)
The following specifications apply for V
DD
= 3.3V unless otherwise specified, limits apply to T
A
= 25C.
Symbol
Parameter
Conditions
LM4810
Units
(Limits)
Typ
(Note 5)
Limit
(Note 7)
I
DD
Supply Current
V
IN
= 0V, I
O
= 0A
1.0
mA
I
SD
Shutdown Current
V
IN
= 0V, V
SHUTDOWN
= V
DD
0.4
A
V
OS
Output Offset Voltage
V
IN
= 0V
4.0
mV
P
O
Output Power
THD+N = 0.1%, f = 1kHz
R
L
= 16
40
mW
R
L
= 32
28
mW
THD+N
Total Harmonic Distortion
P
O
= 25mW, R
L
= 32
f = 20Hz to 20kHz
0.4
%
Crosstalk
Channel Separation
R
L
= 32
; P
O
= 25mW
70
dB
LM4810
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3
Electrical Characteristics
(Notes 2, 3) (Continued)
The following specifications apply for V
DD
= 3.3V unless otherwise specified, limits apply to T
A
= 25C.
Symbol
Parameter
Conditions
LM4810
Units
(Limits)
Typ
(Note 5)
Limit
(Note 7)
PSRR
Power Supply Rejection Ratio
C
B
= 1.0F; Vripple = 200mV
PP
,
f = 1kHz; Input terminated into 50
70
dB
V
SDIH
Shutdown Voltage Input High
0.8 x V
DD
V (min)
V
SDIL
Shutdown Voltage Input Low
0.2 x V
DD
V (max)
Electrical Characteristics
(Notes 2, 3)
The following specifications apply for V
DD
= 2.6V unless otherwise specified, limits apply to T
A
= 25C.
Symbol
Parameter
Conditions
LM4810
Units
(Limits)
Typ
(Note 5)
Limit
(Note 7)
I
DD
Supply Current
V
IN
= 0V, I
O
= 0A
0.9
mA
I
SD
Shutdown Current
V
IN
= 0V, V
SHUTDOWN
= V
DD
0.2
A
V
OS
Output Offset Voltage
V
IN
= 0V
4.0
mV
P
O
Output Power
THD+N = 0.1%, f = 1kHz
R
L
= 16
20
mW
R
L
= 32
16
mW
THD+N
Total Harmonic Distortion
P
O
= 15mW, R
L
= 32
f = 20Hz to 20kHz
0.6
%
Crosstalk
Channel Separation
R
L
= 32
; P
O
= 15mW
70
dB
PSRR
Power Supply Rejection Ratio
C
B
= 1.0F; Vripple = 200mV
PP
,
f = 1kHz; Input terminated into 50
70
dB
V
SDIH
Shutdown Voltage Input High
0.8 x V
DD
V (min)
V
SDIL
Shutdown Voltage Input Low
0.2 x V
DD
V (max)
Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur.
Note 3: All voltages are measured with respect to the ground pin, unless otherwise specified.
Note 4: Human body model, 100pF discharged through a 1.5k
resistor.
Note 5: Typical specifications are specified at +25OC and represent the most likely parametric norm.
Note 6: Tested limits are guaranteed to National's AOQL (Average Outgoing Quality Level).
Note 7: Datasheet max/min specification limits are guaranteed by design, test, or statistical analysis.
Note 8: Machine Model ESD test is covered by specification EIAJ IC-121-1981. A 200pF cap is charged to the specified voltage, then discharged directly into the
IC with no external series resistor (resistance of discharge path must be under 50Ohms).
Note 9: The given
JA
is for an LM4810 packaged in an LDA08B with the Exposed-Dap soldered to a printed circuit board copper pad with an area equivalent to
that of the Exposed-Dap itself.
Note 10: The given
JA
is for an LM4810 packaged in an LDA08B with the Exposed-Dap not soldered to any circuit board copper.
LM4810
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4
External Components Description
(Figure 1)
Components
Functional Description
1. R
i
The inverting input resistance, along with R
f
, set the closed-loop gain. R
i
, along with C
i
, form a high
pass filter with f
c
= 1/(2
R
i
C
i
).
2. C
i
The input coupling capacitor blocks DC voltage at the amplifier's input terminals. C
i
, along with R
i
,
create a highpass filter with f
c
= 1/(2
R
i
C
i
). Refer to the section, Selecting Proper External
Components, for an explanation of determining the value of C
i
.
3. R
f
The feedback resistance, along with R
i
, set closed-loop gain.
4. C
S
This is the supply bypass capacitor. It provides power supply filtering. Refer to the Application
Information section for proper placement and selection of the supply bypass capacitor.
5. C
B
This is the BYPASS pin capacitor. It provides half-supply filtering. Refer to the section, Selecting
Proper External Components, for information concerning proper placement and selection of C
B
.
6. C
O
This is the output coupling capacitor. It blocks the DC voltage at the amplifier's output and forms a high
pass filter with R
L
at f
O
= 1/(2
R
L
C
O
)
Typical Performance Characteristics
THD+N vs Frequency
THD+N vs Frequency
20008985
20008964
THD+N vs Frequency
THD+N vs Frequency
20008965
20008966
LM4810
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