National Semiconductor LM4906 Technical data
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LM4906
1W, Bypass-Capacitor-less Audio Amplifier with Internal
Selectable Gain
LM4906 1W, Bypass-Capacitor-less Audio Amplifier with Internal Selectable Gain
May 2003
General Description
The LM4906 is an audio power amplifier primarily designed
for demanding applications in mobile phones and other portable communication device applications. It is capable of
delivering 1W of continuous average power to an 8Ω BTL
load with less than 1% distortion (THD+N) from a +5V power
supply.
The LM4906 is the first National Semiconductor Boomer
Power Amplifier that does not require an external PSRR
bypass capacitor. The LM4906 also has an internal selectable gain of either 6dB or 12dB. In addition, no output
coupling capacitors or bootstrap capacitors are required
which makes the LM4906 ideally suited for cell phone and
other low voltage portable applications.
The LM4906 contains advanced pop and click circuitry that
eliminates noise, which would otherwise occur during
turn-on and turn-off transitions.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. The LM4906 features a low -power
consumption shutdown mode (the part is enabled by pulling
the SD pin high). Additionally, the LM4906 features an internal thermal shutdown protection mechanism.
Typical Application
Key Specifications
j
Improved PSRR at 217Hz for +3V 71dB
j
Power Output at +5V, THD+N = 1%, 8Ω 1.0W (typ)
j
Power Output at +3V, THD+N = 1%, 8Ω 390mW (typ)
j
Total shutdown power supply current 0.1µA (typ)
Features
n Selectable gain of 6dB (2V/V) or 12dB (4V/V)
n No output or PSRR bypass capacitors required
n Improved “Click and Pop” suppression circuitry
n Very fast turn on time: 5ms (typ)
n Minimum external components
n 2.6 - 5.5V operation
n BTL output can drive capacitive loads
n Ultra low current shutdown mode (SD Low)
Applications
n Portable computers
n Desktop computers
n Multimedia monitors
200571B9
FIGURE 1. Typical Audio Amplifier Application Circuit
Boomer®is a registered trademark of National Semiconductor Corporation.
© 2003 National Semiconductor Corporation DS200571 www.national.com
Connection Diagrams
LM4906
MSOP Package MSOP Marking
Top View
Order Number LM4906MM
See NS Package Number MUB08A
LLP Package LD Marking
Top View
Order Number LM4906LD
See NS Package Number LDA10B
20057102
200571C3
Z - Plant Code
200571F1
X - Date Code
T - Die Traceability
200571F2
Z - Plant Code
XY - Date Code
T - Die Traceability
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LM4906
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 (Note 10) 6.0V
Thermal Resistance
θ
(MSOP) 56˚C/W
JC
θ
(MSOP) 190˚C/W
JA
θ
(LLP) 12˚C/W
JC
θ
(LLP) 63˚C/W
JA
Storage Temperature −65˚C to +150˚C
Input Voltage −0.3V to V
DD
+0.3V
Operating Ratings
Power Dissipation (Notes 3, 11) Internally Limited
ESD Susceptibility (Note 4) 2000V
ESD Susceptibility (Note 5) 200V
Junction Temperature 150˚C
Temperature Range
T
≤ TA≤ T
MIN
MAX
Supply Voltage 2.6V ≤ V
Electrical Characteristics VDD=5V (Notes 1, 2)
The following specifications apply for the circuit shown in Figure 1, unless otherwise specified. Limits apply for T
LM4906
Symbol Parameter Conditions
= 0V, Io= 0A, No Load 3.5 7 mA (max)
V
I
DD
I
SD
V
OS
P
o
T
WU
Quiescent Power Supply Current
Shutdown Current VSD= GND 0.1 2 µA (max)
Output Offset Voltage 7 35 mV (max)
Output Power
Wake-up time 5 ms
THD+N Total Harmonic Distortion+Noise P
PSRR Power Supply Rejection Ratio
IN
V
= 0V, Io= 0A, 8Ω Load 4 8 mA (max)
IN
THD+N = 1% (max);f=1kHz
=8Ω
R
L
= 0.4 Wrms; f = 1kHz 0.2 %
o
V
= 200mV sine p-p
ripple
Input terminated with 10Ω
Gain at 6dB
V
SDIH
V
SDIL
Shutdown Voltage Input High SD Pin High = Part On 1.5 V (min)
Shutdown Voltage Input Low SD Pin Low = Part Off 1.3 V (max)
Typical Limit
(Note 6) (Notes 7, 8)
1.0 0.9 W (min)
67 (f =
217Hz)
70 (f = 1kHz)
−40˚C ≤ TA≤ 85˚C
≤ 5.5V
DD
= 25˚C.
A
Units
(Limits)
dB
Electrical Characteristics VDD=3V (Notes 1, 2)
The following specifications apply for the circuit shown in Figure 1, unless otherwise specified. Limits apply for T
LM4906
Symbol Parameter Conditions
= 0V, Io= 0A, No Load 2.6 6 mA (max)
V
I
DD
I
SD
V
OS
P
o
T
WU
Quiescent Power Supply Current
Shutdown Current VSD= GND 0.1 2 µA (max)
Output Offset Voltage 7 35 mV (max)
Output Power
Wake-up time 4 ms
THD+N Total Harmonic Distortion+Noise P
PSRR Power Supply Rejection Ratio
IN
V
= 0V, Io= 0A, 8Ω Load 3 7 mA (max)
IN
THD+N = 1% (max);f=1kHz
=8Ω
R
L
= 0.15 Wrms; f = 1kHz 0.1 %
o
V
= 200mV sine p-p
ripple
Input terminated with 10Ω
Gain at 6dB
V
SDIH
V
SDIL
Shutdown Voltage Input High SD Pin High = Part On 1.1 V (min)
Shutdown Voltage Input Low SD Pin Low = Part Off 0.9 V (max)
Typical Limit
(Note 6) (Notes 7, 8)
390 mW
71 (f =
217Hz)
73 (f = 1kHz)
= 25˚C.
A
Units
(Limits)
dB
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Note 1: All voltages are measured with respect to the ground pin, unless otherwise specified.
Note 2: 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 andAC electrical specifications under particular test conditions which
LM4906
guarantee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit
is given; however, the typical value is a good indication of device performance.
Note 3: The maximum power dissipation must be derated at elevated temperatures and is dictated by T
allowable power dissipation is P
curves for additional information.
Note 4: Human body model, 100pF discharged through a 1.5kΩ resistor.
Note 5: Machine Model, 220pF–240pF discharged through all pins.
Note 6: Typicals are measured at 25˚C and represent the parametric norm.
Note 7: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).
Note 8: Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis.
Note 9: R
Note 10: If the product is in Shutdown mode and V
If the source impedance limits the current to a max of 10mA, then the device will be protected. If the device is enabled when V
6.5V, no damage will occur, although operation life will be reduced. Operation above 6.5V with no current limit will result in permanent damage.
Note 11: Maximum power dissipation in the device (P
Equation 1 shown in the Application Information section. It may also be obtained from the power dissipation graphs.
is measured from the output pin to ground. This value represents the parallel combination of the 10kΩ output resistors and the two 20kΩ resistors.
OUT
DMAX
=(T
)/θJAor the number given inAbsolute Maximum Ratings, whichever is lower. For the LM4906, see power derating
JMAX–TA
exceeds 6V (to a max of 8V VDD), then most of the excess current will flow through the ESD protection circuits.
DD
) occurs at an output power level significantly below full output power. P
DMAX
, θJA, and the ambient temperature TA. The maximum
JMAX
is greater than 5.5V and less than
DD
can be calculated using
DMAX
External Components Description
Components Functional Description
1. C
2. C
Input coupling capacitor which blocks the DC voltage at the amplifiers input terminals. Also creates a
2
highpass filter with R
for an explanation of how to determine the value of C
Supply bypass capacitor which provides power supply filtering. Refer to the Power Supply Bypassing
1
at fc=1/ (2πRiCi). Refer to the section, Proper Selection of External Components,
i
.
i
section for information concerning proper placement and selection of the supply bypass capacitor.
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Typical Performance Characteristics
LM4906
THD+N vs Frequency
= 5V, RL=8Ω,
V
DD
f = 1kHz, PWR = 500mW
THD+N vs Power Out
= 5V, RL=8Ω, f = 1kHz
V
DD
THD+N vs Frequency
VDD= 3V, RL=8Ω,
f = 1kHz, PWR = 250mW
200571C4 200571C5
THD+N vs Power Out
VDD= 3V, RL=8Ω, f = 1kHz
Power Supply Rejection Ratio
vs Frequency
= 5V, RL=8Ω
V
DD
200571C6 200571C7
Power Supply Rejection Ratio
vs Frequency
VDD= 3V, RL=8Ω
200571E2
200571C9
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