LM4954
LM4954 High Voltage 3 Watt Audio Power Amplifier
Literature Number: SNAS292A
LM4954
High Voltage 3 Watt Audio Power Amplifier
General Description
The LM4954 is an audio power amplifier primarily designed
for demanding applications in mobile phones and other por-
table communication device applications. It is capable of
delivering 2.4 Watts of continuous average power to an 8Ω
BTL load with less than 1% THD+N from a 7V
DC
power
supply.
Boomer audio power amplifiers are designed specifically to
provide high quality output power with a minimal number of
external components. The LM4954 does not require output
coupling capacitors or bootstrap capacitors, and therefore is
ideally suited for lower-power portable applications where
minimal space and power consumption are primary require-
ments.
The LM4954 features a low-power consumption global shut-
down mode which is achieved by driving the shutdown pin
with logic low. Additionally, the LM4954 features an internal
thermal shutdown protection mechanism.
The LM4954 contains advanced pop & click circuitry which
eliminates noises that would otherwise occur during turn-on
and turn-off transitions.
The LM4954 is unity-gain stable and can be configured by
external gain-setting resistors.
Key Specifications
jWide Power Supply
Voltage Range 2.7 ≤V
DD
≤9V
jOutput Power: V
DD
= 7V, 1% THD+N 2.4W (typ)
jQuiescent power supply current 3mA (typ)
jPSRR: V
DD
= 5V and 3V at 217Hz 80dB (typ)
jShutdown power supply current 0.01µA (typ)
Features
nNo output coupling capacitors, snubber networks or
bootstrap capacitors required
nUnity gain stable
nExternally configurable gain
nUltra low current active low shutdown mode
nBTL output can drive capacitive loads up to 100pF
n“Click and pop” suppression circuitry
n2.7V - 9.0V operation
nAvailable in space-saving microSMD package
Applications
nMobile Phones
nPDAs
Typical Application
Boomer®is a registered trademark of National Semiconductor Corporation.
20129111
FIGURE 1. Typical Audio Amplifier Application Circuit
June 2005
LM4954 High Voltage 3 Watt Audio Power Amplifier
© 2005 National Semiconductor Corporation DS201291 www.national.com
Connection Diagrams
9 Bump micro SMD 9 Bump micro SMD Marking
20129186
Top View
Order Number LM4954TL, LM4954TLX
See NS package Number TLA0911A
20129191
Top View
X - Date Code
T - Die Traceability
G - Boomer Family
F2 - LM4954TL
LM4954
www.national.com 2
Absolute Maximum Ratings (Notes 1, 2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage (Note 1) 9.5V
Storage Temperature −65˚C to +150˚C
Input Voltage −0.3V to V
DD
+0.3V
Power Dissipation (Note 3) Internally Limited
ESD Susceptibility (Note 4) 2000V
ESD Susceptibility (Note 5) 200V
Junction Temperature 150˚C
Thermal Resistance
θ
JA
(microSMD) (Note 10) 180˚C/W
Soldering Information
See AN-112 “microSMD Wafers
Level Chip Scale Package.”
Operating Ratings (Notes 1, 2)
Temperature Range
T
MIN
≤T
A
≤T
MAX
−40˚C ≤T
A
≤85˚C
Supply Voltage 2.7V ≤V
DD
≤9V
Electrical Characteristics V
DD
=7V (Notes 1, 2)
The following specifications apply for V
DD
= 7V, A
V-BTL
= 6dB, and R
L
=8Ωunless otherwise specified. Limits apply for T
A
=
25˚C.
Symbol Parameter Conditions
LM4954 Units
(Limits)
Typical Limit
(Note 6) (Notes 7, 8)
I
DD
Quiescent Power Supply Current V
IN
= 0V, R
L
=8ΩBTL 3 5 mA (max)
I
SD
Shutdown Current V
SD
= GND (Note 9) 0.01 1 µA (max)
V
OS
Output Offset Voltage 10 25 mV (max)
P
o
Output Power (Note 11) THD+N = 1% (max); f = 1kHz 2.4 2.2 W (min)
THD+N = 10% (max); f = 1kHz 3.0 W
THD+N Total Harmonic Distortion + Noise
P
O
= 1Wrms; f = 1kHz
A
V-BTL
= 6dB 0.1 %
P
O
= 1Wrms; f = 1kHz
A
V-BTL
= 26dB 0.4 %
PSRR Power Supply Rejection Ratio
V
Ripple
= 200mVsine p-p,
C
B
= 2.2µF, Input terminated
with 10Ωto GND
f
Ripple
= 217Hz, Input Referred
71 54 dB (min)
V
Ripple
= 200mVsine p-p,
C
B
= 2.2µF, Input terminated
with 10Ωto ground
f
Ripple
= 1kHz, Input Referred
71 55 dB (min)
V
SDIH
Shutdown High Input Voltage 1.2 V (min)
V
SDIL
Shutdown Low Input Voltage 0.4 V (max)
T
WU
Wake-up Time C
B
= 2.2µF 130 ms
∈
OUT
Output Noise
A-Wtg, A
V-BTL
= 6dB
Input terminated with 10Ωto GND,
Output Referred
20 µV
RMS
A-Wtg, A
V-BTL
= 26dB
Input terminated with 10Ωto GND,
Output Referred
100 µV
RMS
R
PD
Pull Down Resistor on Shutdown 75 kΩ
LM4954
www.national.com3
Electrical Characteristics V
DD
=5V (Notes 1, 2)
The following specifications apply for V
DD
= 5V, A
V-BTL
= 6dB, and R
L
=8Ωunless otherwise specified. Limits apply for T
A
=
25˚C.
Symbol Parameter Conditions
LM4954 Units
(Limits)
Typical Limit
(Note 6) (Notes 7, 8)
I
DD
Quiescent Power Supply Current V
IN
= 0V, R
L
=8ΩBTL 2.7 5 mA (max)
I
SD
Shutdown Current V
SD
= GND (Note 9) 0.01 1 µA (max)
V
OS
Output Offset Voltage 8 25 mV (max)
P
o
Output Power THD+N = 1% (max); f = 1kHz 1.2 1.1 W (min)
THD+N Total Harmonic Distortion + Noise P
O
= 600mWrms; f = 1kHz 0.1 %
PSRR Power Supply Rejection Ratio
V
ripple
= 200mVsine p-p,
C
B
= 2.2µF, Input terminated
with 10Ωto GND
f
Ripple
= 217Hz, Input Referred
80 63 dB (min)
V
ripple
= 200mVsine p-p,
C
B
= 2.2µF, Input terminated
with 10Ωto GND
f
Ripple
= 1kHz, Input Referred
80 dB
V
SDIH
Shutdown High Input Voltage 1.2 V (min)
V
SDIL
Shutdown Low Input Voltage 0.4 V (max)
T
WU
Wake-up Time C
B
= 2.2µF 130 ms
∈
OUT
Output Noise
A-Wtg, Input terminated with 10Ω
to GND,
Output referred
20 µV
RMS
R
PD
Pul Down Resistor on Shutdown 75 kΩ
Electrical Characteristics V
DD
=3V (Notes 1, 2)
The following specifications apply for V
DD
= 3V, A
V-BTL
= 6dB, and R
L
=8Ωunless otherwise specified. Limits apply for T
A
=
25˚C.
Symbol Parameter Conditions
LM4954 Units
(Limits)
Typical Limit
(Note 6) (Notes 7, 8)
I
DD
Quiescent Power Supply Current V
IN
= 0V, R
L
=8ΩBTL 2.5 5 mA (max)
I
SD
Shutdown Current V
SD
= GND (Note 9) 0.01 1 µA (max)
V
OS
Output Offset Voltage 5 25 mV (max)
P
o
Output Power THD+N = 1% (max); f = 1kHz 380 360 mW (min)
THD+N Total Harmonic Distortion + Noise P
o
= 100mWrms; f = 1kHz 0.18 %
PSRR Power Supply Rejection Ratio
V
ripple
= 200mVsine p-p,
C
B
= 2.2µF, Input teiminated
with 10Ωto GND,
f
Ripple
= 217Hz, Input referred
80 63 dB (min)
V
ripple
= 200mVsine p-p,
C
B
= 2.2µF, Input teiminated
with 10Ωto GND,
f
Ripple
= 1kHz, Input referred
80 dB
V
SDIH
Shutdown High Input Voltage 1.2 V (min)
V
SDIL
Shutdown Low Input Voltage 0.4 V (max)
T
WU
Wake-Up Time C
B
= 2.2µF 130 ms
∈
OUT
Output Noise
A-Wtg, Input terminated with 10Ω
to GND,
Output referred
20 µV
RMS
R
PD
Pull Down Resistor on Shutdown 75 kΩ
LM4954
www.national.com 4
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 and AC electrical specifications under particular test conditions which
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 TJMAX,θJA, and the ambient temperature TA. The maximum
allowable power dissipation is PDMAX =(T
JMAX –T
A)/θJA or the number given in Absolute Maximum Ratings, whichever is lower. For the LM4954, see power
derating curves for additional information.
Note 4: Human body model, 100pF discharged through a 1.5kΩresistor.
Note 5: Machine Model, 220pF – 240pF discharged through all pins.
Note 6: Typical specifications are specified at 25˚C and represent the parametric norm.
Note 7: Tested 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: Shutdown current is measured in a normal room environment. Exposure to direct sunlight in the TL package will increase ISD by a minimum of 2µA.
Note 10: All bumps have the same thermal resistance and contribute equally when used to lower thermal resistance. The θJA in the Thermal Resistance section
is for the ITL package without any heat spreading planes on the PCB.
Note 11: The demo board shown has 1.1in2(710mm2) heat spreading planes on the two internal layers and the bottom layer. The bottom internal layer is electrically
VDD while the top internal and bottom layers are electrically GND. Thermal performance for the demo board is found on the Power Derating graph in the Typical
Performance Characteristics section. 7V operation requires heat spreading planes for the thermal stability.
External Components Description
(Figure 1)
Components Functional Description
1. R
i
Inverting input resistance which sets the closed-loop gain in conjunction with R
f
. This resistor also forms a
high pass filter with C
i
at f
C
= 1/(2πR
i
C
i
).
2. C
i
Input coupling capacitor which blocks the DC voltage at the amplifiers input terminals. Also creates a
highpass filter with R
i
at f
c
= 1/(2πR
i
C
i
). Refer to the section, Proper Selection of External Components,
for an explanation of how to determine the value of C
i
.
3. R
f
Feedback resistance which sets the closed-loop gain in conjunction with R
i
.A
VD
=2*(R
f
/R
i
).
4. C
S
Supply bypass capacitor which provides power supply filtering. Refer to the Power Supply Bypassing
section for information concerning proper placement and selection of the supply bypass capacitor.
5. C
B
Bypass pin capacitor which provides half-supply filtering. Refer to the section, Proper Selection of External
Components, for information concerning proper placement and selection of C
B
.
LM4954
www.national.com5
Typical Performance Characteristics
THD+N vs Output Power
V
DD
= 7V, R
L
=8Ω,A
V
= 6dB,
f = 1kHz, 80kHz BW
THD+N vs Frequency
V
DD
= 7V, R
L
=8Ω,A
V
= 6dB,
P
OUT
= 600mW, 80kHz BW
20129163 20129134
THD+N vs Output Power
V
DD
= 7V, R
L
=8Ω,A
V
= 26dB,
f = 1kHz, 80kHz BW
THD+N vs Frequency
V
DD
= 7V, R
L
=8Ω,A
V
= 26dB,
P
OUT
= 600mW, 80kHz BW
20129164 20129135
THD+N vs Output Power
V
DD
= 5V, R
L
=4Ω,A
V
= 6dB,
f = 1kHz, 80kHz BW
THD+N vs Frequency
V
DD
= 5V, R
L
=4Ω,A
V
= 6dB,
P
OUT
= 100mW, 80kHz BW
20129155 20129132
LM4954
www.national.com 6
Typical Performance Characteristics (Continued)
THD+N vs Output Power
V
DD
= 5V, R
L
=8Ω,A
V
= 6dB,
f = 1kHz, 80kHz BW
THD+N vs Frequency
V
DD
= 5V, R
L
=8Ω,A
V
= 6dB,
P
OUT
= 100mW, 80kHz BW
20129162 20129133
THD+N vs Output Power
V
DD
= 3V, R
L
=4Ω,A
V
= 6dB,
f = 1kHz, 80kHz BW
THD+N vs Frequency
V
DD
= 3V, R
L
=4Ω,A
V
= 6dB,
P
OUT
= 100mW, 80kHz BW
20129136 20129130
THD+N vs Output Power
V
DD
= 3V, R
L
=8Ω,A
V
= 6dB,
f = 1kHz, 80kHz BW
THD+N vs Frequency
V
DD
= 3V, R
L
=8Ω,A
V
= 6dB,
P
OUT
= 100mW, 80kHz BW
20129153 20129131
LM4954
www.national.com7
Typical Performance Characteristics (Continued)
THD+N vs Differential Gain
V
DD
= 7V, R
L
=8Ω,
P
OUT
= 600mW, 80kHz BW
PSRR vs Frequency
V
DD
= 7V, V
RIPPLE
= 200mV
P-P
Input Terminated, 80kHz BW
20129171 20129128
PSRR vs Frequency
V
DD
= 5V, V
RIPPLE
= 200mV
P-P
Input Terminated, 80kHz BW
PSRR vs Frequency
V
DD
= 3V, V
RIPPLE
= 200mV
P-P
Input Terminated, 80kHz BW
20129127 20129126
Output Power vs Supply Voltage
R
L
=4Ω,A
V
= 6dB, 80kHz BW
Output Power vs Supply Voltage
R
L
=8Ω,A
V
= 6dB, 80kHz BW
20129124 20129125
LM4954
www.national.com 8
Typical Performance Characteristics (Continued)
Power Dissipation vs Output Power
V
DD
= 7V, A
V
= 6dB,
THD+N ≤1%, 80kHz BW
Power Dissipation vs Output Power
V
DD
= 5V, A
V
= 6dB,
THD+N ≤1%, 80kHz BW
20129123 20129120
Power Dissipation vs Output Power
V
DD
= 3V, A
V
= 6dB,
THD+N ≤1%, 80kHz BW
Power Derating – 9 bump µSMD
P
DMAX
= 1.26W, V
DD
= 7V,
R
L
=8Ω(Notes 10, 11)
20129112 20129192
Shutdown Threshold vs Supply Voltage
R
L
=8Ω,A
V
= 6dB, 80kHz BW
Supply Current vs Supply Voltage
R
L
=8Ω
20129169 20129129
LM4954
www.national.com9
Application Information
BRIDGE CONFIGURATION EXPLANATION
As shown in Figure 1, the LM4954 has two operational
amplifiers internally, allowing for a few different amplifier
configurations. The first amplifier’s gain is externally config-
urable, while the second amplifier is internally fixed in a
unity-gain, inverting configuration. The closed-loop gain of
the first amplifier is set by selecting the ratio of R
f
to R
i
while
the second amplifier’s gain is fixed by the two internal 20kΩ
resistors. Figure 1 shows that the output of amplifier one
serves as the input to amplifier two which results in both
amplifiers producing signals identical in magnitude, but out
of phase by 180˚. Consequently, the differential gain for the
IC is
A
VD
= 2 *(R
f
/R
i
)
By driving the load differentially through outputs Vo1 and
Vo2, an amplifier configuration commonly referred to as
“bridged mode” is established. Bridged mode operation is
different from the classical single-ended amplifier configura-
tion where one side of the load is connected to ground.
A bridge amplifier design has a few distinct advantages over
the single-ended configuration, as it provides differential
drive to the load, thus doubling output swing for a specified
supply voltage. Four times the output power is possible as
compared to a single-ended amplifier under the same con-
ditions. This increase in attainable output power assumes
that the amplifier is not current limited or clipped. In order to
choose an amplifier’s closed-loop gain without causing ex-
cessive clipping, please refer to the Audio Power Amplifier
Design section.
A bridge configuration, such as the one used in LM4954,
also creates a second advantage over single-ended amplifi-
ers. Since the differential outputs, Vo1 and Vo2, are biased
at half-supply, no net DC voltage exists across the load. This
eliminates the need for an output coupling capacitor which is
required in a single supply, single-ended amplifier configura-
tion. Without an output coupling capacitor, the half-supply
bias across the load would result in both increased internal
IC power dissipation and also possible loudspeaker damage.
POWER DISSIPATION
Power dissipation is a major concern when designing a
successful amplifier, whether the amplifier is bridged or
single-ended. A direct consequence of the increased power
delivered to the load by a bridge amplifier is an increase in
internal power dissipation. Since the LM4954 has two opera-
tional amplifiers in one package, the maximum internal
power dissipation is four times that of a single-ended ampli-
fier. The maximum power dissipation for a given application
can be derived from the power dissipation graphs or from
Equation 1.
P
DMAX
= 4*(V
DD
)
2
/(2π
2
R
L
) (1)
It is critical that the maximum junction temperature (T
JMAX
)
of 150˚C is not exceeded. T
JMAX
can be determined from the
power derating curves by using P
DMAX
and the PC board foil
area. By adding additional copper foil, the thermal resistance
of the application can be reduced from the free air value,
resulting in higher P
DMAX
. Additional copper foil can be
added to any of the leads connected to the LM4954. It is
especially effective when connected to V
DD
, GND, and the
output pins. Refer to the application information on the
LM4954 reference design board for an example of good heat
sinking. If T
JMAX
still exceeds 150˚C, then additional
changes must be made. These changes can include re-
duced supply voltage, higher load impedance, or reduced
ambient temperature. Internal power dissipation is a function
of output power. Refer to the Typical Performance Charac-
teristics curves for power dissipation information for differ-
ent output powers and output loading.
POWER SUPPLY BYPASSING
As with any amplifier, proper supply bypassing is critical for
low noise performance and high power supply rejection. The
capacitor location on both the bypass and power supply pins
should be as close to the device as possible. Typical appli-
cations employ a 5V regulator with 10µF tantalum or elec-
trolytic capacitor and a ceramic bypass capacitor which aid
in supply stability. This does not eliminate the need for
bypassing the supply nodes of the LM4954. The selection of
a bypass capacitor, especially C
B
, is dependent upon PSRR
requirements, click and pop performance (as explained in
the section, Proper Selection of External Components),
system cost, and size constraints.
SHUTDOWN FUNCTION
In order to reduce power consumption while not in use, the
LM4954 contains a shutdown pin to externally turn off the
amplifier’s bias circuitry. This shutdown feature turns the
amplifier off when a logic low is placed on the shutdown pin.
By switching the shutdown pin to ground, the LM4954 supply
current draw will be minimized in idle mode. While the device
will be disabled with shutdown pin voltages less than
0.4V
DC
, the idle current may be greater than the typical
value of 0.01µA. (Idle current is measured with the shutdown
pin tied to ground). The LM4954 has an internal 75kΩpull-
down resistor. If the shutdown pin is left floating the IC will
automatically enter shutdown mode.
PROPER SELECTION OF EXTERNAL COMPONENTS
Proper selection of external components in applications us-
ing integrated power amplifiers is critical to optimize device
and system performance. While the LM4954 is tolerant of
external component combinations, consideration to compo-
nent values must be used to maximize overall system qual-
ity.
The LM4954 is unity-gain stable which gives the designer
maximum system flexibility. The LM4954 should be used in
low gain configurations to minimize THD+N values, and
maximize the signal to noise ratio. Low gain configurations
require large input signals to obtain a given output power.
Input signals equal to or greater than 1 Vrms are available
from sources such as audio codecs. Please refer to the
section, Audio Power Amplifier Design, for a more com-
plete explanation of proper gain selection.
Besides gain, one of the major considerations is the closed-
loop bandwidth of the amplifier. To a large extent, the band-
width is dictated by the choice of external components
shown in Figure 1. The input coupling capacitor, C
i
, forms a
first order high pass filter which limits low frequency re-
sponse. This value should be chosen based on needed
frequency response for a few distinct reasons.
Selection Of Input Capacitor Size
Large input capacitors are both expensive and space hungry
for portable designs. Clearly, a certain sized capacitor is
needed to couple in low frequencies without severe attenu-
ation. But in many cases the speakers used in portable
systems, whether internal or external, have little ability to
LM4954
www.national.com 10
Application Information (Continued)
reproduce signals below 100Hz to 150Hz. Thus, using a
large input capacitor may not increase actual system perfor-
mance.
In addition to system cost and size, click and pop perfor-
mance is affected by the size of the input coupling capacitor,
C
i
. A larger input coupling capacitor requires more charge to
reach its quiescent DC voltage (nominally 1/2V
DD
). This
charge comes from the output via the feedback and is apt to
create pops upon device enable. Thus, by minimizing the
capacitor size based on necessary low frequency response,
turn-on pops can be minimized.
Besides minimizing the input capacitor size, careful consid-
eration should be paid to the bypass capacitor value. Choos-
ing C
B
equal to 2.2µF along with a small value of C
i
(in the
range of 0.1µF to 0.39µF), should produce a virtually click-
less and popless shutdown function. While the device will
function properly, (no oscillations or motorboating), with C
B
equal to 0.1µF.
AUDIO POWER AMPLIFIER DESIGN
A designer must first determine the minimum supply rail to
obtain the specified output power. By extrapolating from the
Output Power vs Supply Voltage graphs in the Typical Per-
formance Characteristics section, the supply rail can be
easily found.
At this time, the designer must make sure that the power
supply choice along with the output impedance does not
violate the conditions explained in the Power Dissipation
section.
Once the power dissipation equations have been addressed,
the required differential gain can be determined from Equa-
tion 2.
(2)
A
VD
=(R
f
/R
i
)2
The LM4954 is unity-gain stable and requires no external
components besides gain-setting resistors, an input coupling
capacitor, and proper supply bypassing in the typical appli-
cation. However, if a closed-loop differential gain of greater
than 10 is required, a feedback capacitor (C
F
) may be
needed as shown in Figure 2 to bandwidth limit the amplifier.
This feedback capacitor creates a low pass filter that elimi-
nates possible high frequency oscillations. Care should be
taken when calculating the -3dB frequency in that an incor-
rect combination of R
F
and C
F
will cause rolloff before
20kHz. A typical combination of feedback resistor and ca-
pacitor that will not produce audio band high frequency rolloff
is R
F
= 20kΩand C
F
= 25pf. These components result in a
-3dB point of approximately 320 kHz. To calculate the value
of the capacitor for a given -3dB point, use Equation 3 below:
C
F
= 1/(2πf
3dB
R
F
) (F) (3)
20129108
FIGURE 2. HIGHER GAIN AUDIO AMPLIFIER
LM4954
www.national.com11
Application Information (Continued)
20129109
FIGURE 3. DIFFERENTIAL AMPLIFIER CONFIGURATION FOR LM4954
20129110
FIGURE 4. REFERENCE DESIGN BOARD SCHEMATIC
LM4954
www.national.com 12
Application Information (Continued)
TABLE 1. Mono LM4954 Reference Design Boards Bill of Materials
Designator Value Tolerance Part Description Comment
R
i
20kΩ1% 1/10W, 1% 0805 Resistor
R
F
20kΩ1% 1/10W, 1% 0805 Resistor
C
i
0.39µF 10% Ceramic 1206 Capacitor, 10%
C
F
Part not used
C
S
2.2µF 10% 16V Tantalum 1210 Capacitor
C
B
2.2µF 10% 16V Tantalum 1210 Capacitor
J
1
,J
3
,J
4
0.100” 1x2 header, vertical
mount
Input, Output,
Vdd/GND
J
2
0.100” 1x3 header, vertical
mount
Shutdown control
PCB LAYOUT GUIDELINES
This section provides practical guidelines for mixed signal
PCB layout that involves various digital/analog power and
ground traces. Designers should note that these are only
"rule-of-thumb" recommendations and the actual results will
depend heavily on the final layout.
GENERAL MIXED SIGNAL LAYOUT
RECOMMENDATIONS
Power and Ground Circuits
For a two layer mixed signal design, it is important to isolate
the digital power and ground trace paths from the analog
power and ground trace paths. Star trace routing techniques
(bringing individual traces back to a central point rather than
daisy chaining traces together in a serial manner) can have
a major impact on low level signal performance. Star trace
routing refers to using individual traces to feed power and
ground to each circuit or even device. This technique re-
quires a greater amount of design time but will not increase
the final price of the board. The only extra parts required may
be some jumpers.
Single-Point Power / Ground Connections
The analog power traces should be connected to the digital
traces through a single point (link). A "Pi-filter" can be helpful
in minimizing high frequency noise coupling between the
analog and digital sections. It is further recommended to put
digital and analog power traces over the corresponding digi-
tal and analog ground traces to minimize noise coupling.
Placement of Digital and Analog Components
All digital components and high-speed digital signals traces
should be located as far away as possible from analog
components and circuit traces.
Avoiding Typical Design / Layout Problems
Avoid ground loops or running digital and analog traces
parallel to each other (side-by-side) on the same PCB layer.
When traces must cross over each other do it at 90 degrees.
Running digital and analog traces at 90 degrees to each
other from the top to the bottom side as much as possible will
minimize capacitive noise coupling and cross talk.
LM4954
www.national.com 14
Revision History
Rev Date Description
1.1 4/29/05 Added curves 71 and 72. Edited Note 10. Changed
Av = 26dB to 6dB under 7V EC table. Edited
SHUTDOWN FUNCTION under the Application
section.
1.2 6/08/05 Removed all the LLP pkg references. Changed
TLA09XXX into TLA0911A. Changed X1 and X2
measurements.
1.3 6/15/05 Fixed some typos.
Initial WEB release.
1.4 6/20/05 Replaced curve 20129170 with 20129192.
1.5 6/22/05 Split Note 10 and added Note 11. Re-released to the
WEB.
LM4954
www.national.com15
Physical Dimensions inches (millimeters) unless otherwise noted
9-Bump micro SMD
Order Number LM4954TL, LM4954TLX
NS Package Number TLA0911A
X1 = 1.488±0.03 X2 = 1.488±0.03 X3 = 0.60±0.075
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves
the right at any time without notice to change said circuitry and specifications.
For the most current product information visit us at www.national.com.
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS
WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR
CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body, or
(b) support or sustain life, and whose failure to perform when
properly used in accordance with instructions for use
provided in the labeling, can be reasonably expected to result
in a significant injury to the user.
2. A critical component is any component of a life support
device or system whose failure to perform can be reasonably
expected to cause the failure of the life support device or
system, or to affect its safety or effectiveness.
BANNED SUBSTANCE COMPLIANCE
National Semiconductor manufactures products and uses packing materials that meet the provisions of the Customer Products
Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain
no ‘‘Banned Substances’’ as defined in CSP-9-111S2.
Leadfree products are RoHS compliant.
National Semiconductor
Americas Customer
Support Center
Email: new.feedback@nsc.com
Tel: 1-800-272-9959
National Semiconductor
Europe Customer Support Center
Fax: +49 (0) 180-530 85 86
Email: europe.support@nsc.com
Deutsch Tel: +49 (0) 69 9508 6208
English Tel: +44 (0) 870 24 0 2171
Français Tel: +33 (0) 1 41 91 8790
National Semiconductor
Asia Pacific Customer
Support Center
Email: ap.support@nsc.com
National Semiconductor
Japan Customer Support Center
Fax: 81-3-5639-7507
Email: jpn.feedback@nsc.com
Tel: 81-3-5639-7560
www.national.com
LM4954 High Voltage 3 Watt Audio Power Amplifier
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements,
and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should
obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are
sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment.
TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard
warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where
mandated by government requirements, testing of all parameters of each product is not necessarily performed.
TI assumes no liability for applications assistance or customer product design. Customers are responsible for their products and
applications using TI components. To minimize the risks associated with customer products and applications, customers should provide
adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right,
or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information
published by TI regarding third-party products or services does not constitute a license from TI to use such products or services or a
warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual
property of the third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied
by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive
business practice. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional
restrictions.
Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all
express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not
responsible or liable for any such statements.
TI products are not authorized for use in safety-critical applications (such as life support) where a failure of the TI product would reasonably
be expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governing
such use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, and
acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products
and any use of TI products in such safety-critical applications, notwithstanding any applications-related information or support that may be
provided by TI. Further, Buyers must fully indemnify TI and its representatives against any damages arising out of the use of TI products in
such safety-critical applications.
TI products are neither designed nor intended for use in military/aerospace applications or environments unless the TI products are
specifically designated by TI as military-grade or "enhanced plastic."Only products designated by TI as military-grade meet military
specifications. Buyers acknowledge and agree that any such use of TI products which TI has not designated as military-grade is solely at
the Buyer's risk, and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use.
TI products are neither designed nor intended for use in automotive applications or environments unless the specific TI products are
designated by TI as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designated
products in automotive applications, TI will not be responsible for any failure to meet such requirements.
Following are URLs where you can obtain information on other Texas Instruments products and application solutions:
Products Applications
Audio www.ti.com/audio Communications and Telecom www.ti.com/communications
Amplifiers amplifier.ti.com Computers and Peripherals www.ti.com/computers
Data Converters dataconverter.ti.com Consumer Electronics www.ti.com/consumer-apps
DLP®Products www.dlp.com Energy and Lighting www.ti.com/energy
DSP dsp.ti.com Industrial www.ti.com/industrial
Clocks and Timers www.ti.com/clocks Medical www.ti.com/medical
Interface interface.ti.com Security www.ti.com/security
Logic logic.ti.com Space, Avionics and Defense www.ti.com/space-avionics-defense
Power Mgmt power.ti.com Transportation and Automotive www.ti.com/automotive
Microcontrollers microcontroller.ti.com Video and Imaging www.ti.com/video
RFID www.ti-rfid.com
OMAP Mobile Processors www.ti.com/omap
Wireless Connectivity www.ti.com/wirelessconnectivity
TI E2E Community Home Page e2e.ti.com
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright ©2011, Texas Instruments Incorporated
