LM4940
6W Stereo Audio Power Amplifier
General Description
Key Specifications
The LM4940 is a dual audio power amplifier primarily designed for demanding applications in flat panel monitors and
TV’s. It is capable of delivering 6 watts per channel to a 4Ω
load with less than 10% THD+N while operating on a
14.4VDC power supply.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. The LM4940 does not require bootstrap capacitors or snubber circuits. Therefore, it is ideally
suited for display applications requiring high power and minimal size.
The LM4940 features a low-power consumption active-low
shutdown mode. Additionally, the LM4940 features an internal thermal shutdown protection mechanism along with short
circuit protection.
The LM4940 contains advanced pop & click circuitry that
eliminates noises which would otherwise occur during
turn-on and turn-off transitions.
The LM4940 is a unity-gain stable and can be configured by
external gain-setting resistors.
j Quiscent Power Supply Current
40mA (max)
j POUT (SE)
VDD = 14.4V, RL = 4Ω, 10% THD+N
j Shutdown current
6W (typ)
40µA (typ)
Features
n Pop & click circuitry eliminates noise during turn-on and
turn-off transitions
n Low current, active-low shutdown mode
n Low quiescent current
n Stereo 6W output, RL = 4Ω
n Short circuit protection
n Unity-gain stable
n External gain configuration capability
Applications
n Flat Panel Monitors
n Flat Panel TV’s
n Computer Sound Cards
Typical Application
20075672
FIGURE 1. Typical Stereo Audio Amplifier Application Circuit
Boomer ® is a registered trademark of National Semiconductor Corporation.
© 2005 National Semiconductor Corporation
DS200756
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LM4940 6W Stereo Audio Power Amplifier
April 2005
LM4940
Connection Diagram
Plastic Package, TO-263
200756E7
Top View
U = Wafer Fab Code
Z = Assembly Plant Code
XY = Date Code
TT = Die Traceability
Order Number LM4940TS
See NS Package Number TS9A
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2
Junction Temperature
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Thermal Resistance
Supply Voltage (pin 6, referenced
to GND, pins 4 and 5)
150˚C
θJC (TS)
4˚C/W
θJA (TS) (Note 3)
20˚C/W
θJC (TA)
18.0V
Storage Temperature
4˚C/W
θJA (TA) (Note 3)
20˚C/W
−65˚C to +150˚C
Input Voltage
Operating Ratings
−0.3V to VDD + 0.3V
pins 3 and 7
pins 1, 2, 8, and 9
Temperature Range
−0.3V to 9.5V
Power Dissipation (Note 3)
TMIN ≤ TA ≤ TMAX
Internally limited
ESD Susceptibility (Note 4)
2000V
ESD Susceptibility (Note 5)
200V
−40˚C ≤ T
A
≤ 85˚C
10V ≤ VDD ≤ 16V
Supply Voltage
Electrical Characteristics VDD = 12V (Notes 1, 2)
The following specifications apply for VDD = 12V, AV = 10, RL = 4Ω, f = 1kHz unless otherwise specified. Limits apply for TA =
25˚C.
Symbol
Parameter
Conditions
LM4940
Typical
(Note 6)
Limit
(Notes 7, 8)
Units
(Limits)
IDD
Quiescent Power Supply Current
VIN = 0V, IO = 0A, No Load
16
40
mA (max)
VSHUTDOWN = GND (Note 9)
40
ISD
Shutdown Current
100
µA (max)
VSDIH
Shutdown Voltage Input High
2.0
VDD/2
V (min)
V (max)
VSDIL
Shutdown Voltage Input Low
0.4
V (max)
Single Channel
PO
Output Power
THD+N = 1%
3.1
THD+N = 10%
4.2
VDD = 14.4V, THD+N = 10%
6.0
2.8
W (min)
THD+N
Total Harmomic Distortion + Noise
PO = 1Wrms, AV = 10, f = 1kHz
0.15
%
eOS
Output Noise
A-Weighted Filter, VIN = 0V,
Input Referred
10
µV
XTALK
Channel Separation
PO = 1W
70
dB
PSRR
Power Supply Rejection Ratio
VRIPPLE = 200mVp-p, fRIPPLE =
1kHz
56
dB
Note 1: All voltages are measured with respect to the GND 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 P DMAX = (TJMAX − TA) / θJA or the given in Absolute Maximum Ratings, whichever is lower. For the LM4940 typical application (shown
in Figure 1) with VDD = 12V, RL = 4Ω stereo operation the total power dissipation is 3.65W. θJA = 20˚C/W for both TO263 and TO220 packages mounted to 16in2
heatsink surface area.
Note 4: Human body model, 100pF discharged through a 1.5 kΩ 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: Shutdown current is measured in a normal room environment. The Shutdown pin should be driven as close as possible to GND for minimum shutdown
current.
3
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LM4940
Absolute Maximum Ratings (Notes 1, 2)
LM4940
Typical Application
20075672
FIGURE 2. Typical Stereo Audio Amplifier Application Circuit
External Components Description
Components
Refer to (Figure 1.)
Functional Description
1.
RIN
This is the inverting input resistance that, along with RF, sets the closed-loop gain. Input
resistance RIN and input capacitance CIN form a high pass filter. The filter’s cutoff frequency is fC
= 1/(2πRINCIN).
2.
CIN
This is the input coupling capacitor. It blocks DC voltage at the amplifier’s inverting input. CIN and
RIN create a highpass filter. The filter’s cutoff frequency is fC = 1/(2πRINCIN). Refer to the
SELECTING EXTERNAL COMPONENTS section for an explanation of determining CIN’s value.
3.
RF
This is the feedback resistance that, along with Ri, sets closed-loop gain.
4.
CS
The supply bypass capacitor. Refer to the POWER SUPPLY BYPASSING section for information
about properly placing, and selecting the value of, this capacitor.
5.
6.
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This capacitor filters the half-supply voltage present on the BYPASS pin. Refer to the Application
CBYPASS section, SELECTING EXTERNAL COMPONENTS, for information about properly placing, and
selecting the value of, this capacitor.
COUT
This is the output coupling capacitor. It blocks the nominal VDD/2 voltage present at the output
and prevents it from reaching the load. COUT and RL form a high pass filter whose cutoff
frequency is fC = 1/(2πRLCOUT). Refer to the SELECTING EXTERNAL COMPONENTS section
for an explanation of determining COUT’s value.
4
LM4940
Typical Performance Characteristics
THD+N vs Frequency
THD+N vs Frequency
20075699
200756A0
VDD = 12V, RL = 4Ω, SE operation,
both channels driven and loaded (average shown),
POUT = 1W, AV = 1
VDD = 12V, RL = 4Ω, SE operation,
both channels driven and loaded (average shown),
POUT = 2.5W, AV = 1
THD+N vs Frequency
THD+N vs Output Power
200756A1
200756F3
VDD = 12V, RL = 8Ω, SE operation,
both channels driven and loaded (average shown),
POUT = 1W, AV = 1
VDD = 14.4V, RL = 4Ω, SE operation, AV = 1
single channel driven/single channel measured,
fIN = 1kHz
THD+N vs Output Power
THD+N vs Output Power
200756D9
200756E0
VDD = 12V, RL = 4Ω, SE operation, AV = 1
single channel driven/single channel measured,
fIN = 1kHz
VDD = 12V, RL = 8Ω, SE operation, AV = 1
single channel driven/single channel measured,
fIN = 1kHz
5
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LM4940
Typical Performance Characteristics
(Continued)
THD+N vs Output Power
THD+N vs Output Power
200756E1
200756C7
VDD = 12V, RL = 16Ω, SE operation, AV = 1
single channel driven/single channel measured,
fIN = 1kHz
VDD = 12V, RL = 4Ω, SE operation, AV = 10
single channel driven/single channel measured,
fIN = 1kHz
THD+N vs Output Power
THD+N vs Output Power
200756C6
20075666
VDD = 12V, RL = 8Ω, SE operation, AV = 10
single channel driven/single channel measured,
fIN = 1kHz
VDD = 12V, RL = 16Ω, SE operation, AV = 10
single channel driven/single channel measured,
fIN = 1kHz
Output Power vs Power Supply Voltage
Output Power vs Power Supply Voltage
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200756E9
RL = 4Ω, SE operation, fIN = 1kHz,
both channels driven and loaded (average shown),
at (from top to bottom at 12V): THD+N = 10%,
THD+N = 1%
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RL = 8Ω, SE operation, fIN = 1kHz,
both channels driven and loaded (average shown),
at (from top to bottom at 12V): THD+N = 10%,
THD+N = 1%
6
(Continued)
Output Power vs Power Supply Voltage
Power Supply Rejection vs Frequency
20075667
200756B8
RL = 16Ω, SE operation, fIN = 1kHz,
both channels driven and loaded (average shown),
at (from top to bottom at 12V): THD+N = 10%,
THD+N = 1%
VDD = 12V, RL = 8Ω, SE operation,
VRIPPLE = 200mVp-p, at (from top to bottom at 60Hz):
CBYPASS = 1µF, CBYPASS = 4.7µF, CBYPASS = 10µF,
Power Supply Rejection vs Frequency
Total Power Dissipation vs Load Dissipation
20075681
200756D8
VDD = 12V, RL = 8Ω, SE operation, VRIPPLE = 200mVp-p,
AV = 10, at (from top to bottom at 60Hz):
CBYPASS = 1µF, CBYPASS = 4.7µF, CBYPASS = 10µF
VDD = 12V, SE operation, fIN = 1kHz,
at (from top to bottom at 1W):
RL = 4Ω, RL = 8Ω
Output Power vs Load Resistance
Channel-to-Channel Crosstalk vs Frequency
20075691
20075698
VDD = 12V, SE operation, fIN = 1kHz,
both channels driven and loaded,
at (from top to bottom at 15Ω):
THD+N = 10%, THD+N = 1%
VDD = 12V, RL = 4Ω, POUT = 1W, SE operation,
at (from top to bottom at 1kHz): VINB driven,
VOUTA measured; VINA driven, VOUTB measured
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LM4940
Typical Performance Characteristics
LM4940
Typical Performance Characteristics
(Continued)
Channel-to-Channel Crosstalk vs Frequency
Power Supply Current vs Power Supply Voltage
200756F0
200756A3
VDD = 12V, RL = 8Ω, POUT = 1W, SE operation,
at (from top to bottom at 1kHz): VINB driven,
VOUTA measured; VINA driven, VOUTB measured
RL = 4Ω, SE operation
VIN = 0V, RSOURCE = 50Ω
Clipping Voltage vs Power Supply Voltage
Clipping Voltage vs Power Supply Voltage
200756F1
200756F2
RL = 4Ω, SE operation, fIN = 1kHz
both channels driven and loaded,
at (from top to bottom at 13V):
negative signal swing, positive signal swing
RL = 8Ω, SE operation, fIN = 1kHz
both channels driven and loaded, at (from top to bottom
at 13V):
negative signal swing, positive signal swing
Power Dissipation vs Ambient Temperature
200756E4
VDD = 12V, RL = 8Ω (SE), fIN = 1kHz,
(from top to bottom at 120˚C): 16in2 copper plane
heatsink area,
8in2 copper plane heatsink area
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8
LM4940
Application Information
20075672
FIGURE 3. Typical LM4940 Stereo Amplifier Application Circuit
nect the two layers together under the tab with a 5x5 array of
vias. For the TA package, use an external heatsink with a
thermal impedance that is less than 20˚C/W. At any given
ambient temperature TA, use Equation (4) to find the maximum internal power dissipation supported by the IC packaging. Rearranging Equation (4) and substituting PDMAX for
PDMAX’ results in Equation (5). This equation gives the maximum ambient temperature that still allows maximum stereo
power dissipation without violating the LM4940’s maximum
junction temperature.
HIGH VOLTAGE BOOMER WITH INCREASED OUTPUT
POWER
Unlike previous 5V Boomer ® amplifiers, the LM4940 is designed to operate over a power supply voltages range of 10V
to 15V. Operating on a 12V power supply, the LM4940 will
deliver 3.1W per channel into 4Ω loads with no more than
1% THD+N.
POWER DISSIPATION
Power dissipation is a major concern when designing a
successful single-ended amplifier. Equation (2) states the
maximum power dissipation point for a single-ended amplifier operating at a given supply voltage and driving a specified output load.
PDMAX-SE = (VDD)
2
/ (2π2RL):
Single Ended
TA = TJMAX - PDMAX-SEθJA
For a typical application with a 12V power supply and two 4Ω
SE loads, the maximum ambient temperature that allows
maximum stereo power dissipation without exceeding the
maximum junction temperature is approximately 113˚C for
the TS package.
(1)
The LM4940’s dissipation is twice the value given by Equation (2) when driving two SE loads. For a 12V supply and two
8Ω SE loads, the LM4940’s dissipation is 1.82W.
TJMAX = PDMAX-SEθJA + TA
The maximum power dissipation point (twice the value given
by Equation (2)) must not exceed the power dissipation
given by Equation (4):
PDMAX’ = (TJMAX - TA) / θJA
(3)
(4)
Equation (6) gives the maximum junction temperature
TJMAX. If the result violates the LM4940’s 150˚C, reduce the
maximum junction temperature by reducing the power supply voltage or increasing the load resistance. Further allowance should be made for increased ambient temperatures.
The above examples assume that a device is operating
around the maximum power dissipation point. Since internal
power dissipation is a function of output power, higher ambient temperatures are allowed as output power or duty
cycle decreases.
(2)
The LM4940’s TJMAX = 150˚C. In the TS package, the
LM4940’s θJA is 20˚C/W when the metal tab is soldered to a
copper plane of at least 16in2. This plane can be split between the top and bottom layers of a two-sided PCB. Con9
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LM4940
Application Information
SELECTING EXTERNAL COMPONENTS
(Continued)
Input Capacitor Value Selection
Two quantities determine the value of the input coupling
capacitor: the lowest audio frequency that requires amplification and desired output transient suppression.
If the result of Equation (3) is greater than that of Equation
(4), then decrease the supply voltage, increase the load
impedance, or reduce the ambient temperature. Further,
ensure that speakers rated at a nominal 4Ω do not fall below
3Ω. If these measures are insufficient, a heat sink can be
added to reduce θJA. The heat sink can be created using
additional copper area around the package, with connections to the ground pins, supply pin and amplifier output pins.
Refer to the Typical Performance Characteristics curves
for power dissipation information at lower output power levels.
As shown in Figure 3, the input resistor (RIN) and the input
capacitor (CIN) produce a high pass filter cutoff frequency
that is found using Equation (7).
(5)
fc = 1/2πRiCi
As an example when using a speaker with a low frequency
limit of 50Hz, Ci, using Equation (7) is 0.159µF. The 0.39µF
CINA shown in Figure 3allows the LM4940 to drive high
efficiency, full range speaker whose response extends below
30Hz.
POWER SUPPLY VOLTAGE LIMITS
Continuous proper operation is ensured by never exceeding
the voltage applied to any pin, with respect to ground, as
listed in the Absolute Maximum Ratings section.
Output Coupling Capacitor Value Selection
The capacitors COUTA and COUTB that block the VDD/2 output DC bias voltage and couple the output AC signal to the
amplifier loads also determine low frequency response.
These capacitors, combined with their respective loads create a highpass filter cutoff frequency. The frequency is also
given by Equation (6).
Using the same conditions as above, with a 4Ω speaker,
COUT is 820µF (nearest common valve).
POWER SUPPLY BYPASSING
As with any power amplifier, proper supply bypassing is
critical for low noise performance and high power supply
rejection. Applications that employ a voltage regulator typically use a 10µF in parallel with a 0.1µF filter capacitors to
stabilize the regulator’s output, reduce noise on the supply
line, and improve the supply’s transient response. However,
their presence does not eliminate the need for a local 1.0µF
tantalum bypass capacitance connected between the
LM4940’s supply pins and ground. Do not substitute a ceramic capacitor for the tantalum. Doing so may cause oscillation. Keep the length of leads and traces that connect
capacitors between the LM4940’s power supply pin and
ground as short as possible. Connecting a 10µF capacitor,
CBYPASS, between the BYPASS pin and ground improves
the internal bias voltage’s stability and improves the amplifier’s PSRR. The PSRR improvements increase as the bypass pin capacitor value increases. Too large, however,
increases turn-on time and can compromise the amplifier’s
click and pop performance. The selection of bypass capacitor values, especially CBYPASS, depends on desired PSRR
requirements, click and pop performance (as explained in
the section, SELECTING EXTERNAL COMPONENTS),
system cost, and size constraints.
Bypass Capacitor Value
Besides minimizing the input capacitor size, careful consideration should be paid to value of CBYPASS, the capacitor
connected to the BYPASS pin. Since CBYPASS determines
how fast the LM4940 settles to quiescent operation, its value
is critical when minimizing turn-on pops. The slower the
LM4940’s outputs ramp to their quiescent DC voltage (nominally VDD/2), the smaller the turn-on pop. Choosing CBYPASS
equal to 10µF along with a small value of CIN (in the range of
0.1µF to 0.39µF), produces a click-less and pop-less shutdown function. As discussed above, choosing CIN no larger
than necessary for the desired bandwidth helps minimize
clicks and pops.
OPTIMIZING CLICK AND POP REDUCTION
PERFORMANCE
The LM4940 contains circuitry that eliminates turn-on and
shutdown transients ("clicks and pops"). For this discussion,
turn-on refers to either applying the power supply voltage or
when the micro-power shutdown mode is deactivated.
As the VDD/2 voltage present at the BYPASS pin ramps to its
final value, the LM4940’s internal amplifiers are configured
as unity gain buffers and are disconnected from the AMPA
and AMPB pins. An internal current source charges the capacitor connected between the BYPASS pin and GND in a
controlled manner. Ideally, the input and outputs track the
voltage applied to the BYPASS pin. The gain of the internal
amplifiers remains unity until the voltage applied to the BYPASS pin.
The gain of the internal amplifiers remains unity until the
voltage on the bypass pin reaches VDD/2. As soon as the
voltage on the bypass pin is stable, the device becomes fully
operational and the amplifier outputs are reconnected to
their respective output pins. Although the BYPASS pin current cannot be modified, changing the size of CBYPASS alters
the device’s turn-on time. Here are some typical turn-on
times for various values of CBYPASS:
MICRO-POWER SHUTDOWN
The LM4940 features an active-low micro-power shutdown
mode. When active, the LM4940’s micro-power shutdown
feature turns off the amplifier’s bias circuitry, reducing the
supply current. The low 40µA typical shutdown current is
achieved by applying a voltage to the SHUTDOWN pin that
is as near to GND as possible. A voltage that is greater than
GND may increase the shutdown current.
There are a few methods to control the micro-power shutdown. These include using a single-pole, single-throw switch
(SPST), a microprocessor, or a microcontroller. When using
a switch, connect a 100kΩ pull-up resistor between the
SHUTDOWN pin and VDD and the SPST switch between the
SHUTDOWN pin and GND. Select normal amplifier operation by opening the switch. Closing the switch applies GND
to the SHUTDOWN pin, activating micro-power shutdown.
The switch and resistor guarantee that the SHUTDOWN pin
will not float. This prevents unwanted state changes. In a
system with a microprocessor or a microcontroller, use a
digital output to apply the active-state voltage to the SHUTDOWN pin.
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10
(Continued)
CB (µF)
TON (ms)
1.0
120
2.2
120
4.7
200
10
440
(8)
Thus, a minimum gain of 11.6 allows the LM4940’s to reach
full output swing and maintain low noise and THD+N performance. For this example, let AV = 12. The amplifier’s overall
BTL gain is set using the input (RINA) and feedback (R)
resistors of the first amplifier in the series BTL configuration.
Additionaly, AV-BTL is twice the gain set by the first amplifier’s
RIN and Rf. With the desired input impedance set at 20kΩ,
the feedback resistor is found using Equation (11).
In order eliminate "clicks and pops", all capacitors must be
discharged before turn-on. Rapidly switching VDD may not
allow the capacitors to fully discharge, which may cause
"clicks and pops".
There is a relationship between the value of CIN and
CBYPASS that ensures minimum output transient when power
is applied or the shutdown mode is deactivated. Best performance is achieved by setting the time constant created by
CIN and Ri + Rf to a value less than the turn-on time for a
given value of CBYPASS as shown in the table above.
Rf / RIN = AV
The value of Rf is 240kΩ. The nominal output power is 3W.
The last step in this design example is setting the amplifier’s
-3dB frequency bandwidth. To achieve the desired ± 0.25dB
pass band magnitude variation limit, the low frequency response must extend to at least one-fifth the lower bandwidth
limit and the high frequency response must extend to at least
five times the upper bandwidth limit. The gain variation for
both response limits is 0.17dB, well within the ± 0.25dBdesired limit. The results are an
AUDIO POWER AMPLIFIER DESIGN
Audio Amplifier Design: Driving 3W into a 4Ω load
The following are the desired operational parameters:
Power Output
3WRMS
Load Impedance
Input Level
(9)
4Ω
0.3VRMS (max)
Input Impedance
fL = 100Hz / 5 = 20Hz
(10)
fL = 20kHz x 5 = 100kHz
(11)
20kΩ
Bandwidth
100Hz–20kHz ± 0.25dB
The design begins by specifying the minimum supply voltage
necessary to obtain the specified output power. One way to
find the minimum supply voltage is to use the Output Power
vs Power Supply Voltage curve in the Typical Performance
Characteristics section. Another way, using Equation (8), is
to calculate the peak output voltage necessary to achieve
the desired output power for a given load impedance. To
account for the amplifier’s dropout voltage, two additional
voltages, based on the Clipping Dropout Voltage vs Power
Supply Voltage in the Typical Performance Characteristics curves, must be added to the result obtained by Equation (8). The result is Equation (9).
and an
As mentioned in the SELECTING EXTERNAL COMPONENTS section, RINA and CINA, as well as COUT and RL,
create a highpass filter that sets the amplifier’s lower bandpass frequency limit. Find the coupling capacitor’s value
using Equation (14).
CIN = 1 / 2πRINfL
(12)
The result is
1 / (2πx20kΩx20Hz) = 0.398µF = CIN
(6)
and
VDD = VOUTPEAK + VODTOP + VODBOT
(7)
1 / (2πx4Ωx20Hz) = 1989µF = COUT
The Output Power vs. Power Supply Voltage graph for an 8Ω
load indicates a minimum supply voltage of 11.8V. The commonly used 12V supply voltage easily meets this. The additional voltage creates the benefit of headroom, allowing the
LM4940 to produce an output power of 3W without clipping
or other audible distortion. The choice of supply voltage must
also not create a situation that violates of maximum power
dissipation as explained above in the Power Dissipation
section. After satisfying the LM4940’s power dissipation requirements, the minimum differential gain needed to achieve
3W dissipation in a 4Ω BTL load is found using Equation
(10).
Use a 0.39µF capacitor for CIN and a 2000µF capacitor for
COUT, the closest standard values.
The product of the desired high frequency cutoff (100kHz in
this example) and the differential gain AV, determines the
upper passband response limit. With AV = 12 and fH =
100kHz, the closed-loop gain bandwidth product (GBWP) is
1.2mHz. This is less than the LM4940’s 3.5MHz GBWP. With
this margin, the amplifier can be used in designs that require
more differential gain while avoiding performance restricting
bandwidth limitations.
11
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LM4940
Application Information
LM4940
Application Information
This circuit board is easy to use. Apply 12V and ground to
the board’s VDD and GND pads, respectively. Connect a
speaker between the board’s OUTA and OUTB outputs and
their respective GND terminals.
(Continued)
RECOMMENDED PRINTED CIRCUIT BOARD LAYOUT
Figure 5 through Figure 7 show the recommended two-layer
PC board layout that is optimized for the TO263-packaged
LM4940 and associated external components. This circuit
board is designed for use with an external 12V supply and
4Ω(min) speakers.
Demonstration Board Layout
20075663
FIGURE 4. Recommended TS PCB Layout:
Top Silkscreen
20075664
FIGURE 5. Recommended TS PCB Layout:
Top Layer
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12
LM4940
Demonstration Board Layout
(Continued)
20075665
FIGURE 6. Recommended TS PCB Layout:
Bottom Layer
13
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LM4940 6W Stereo Audio Power Amplifier
Physical Dimensions
inches (millimeters) unless otherwise noted
Plastic Package,
Order Number LM4940TS
NS Package Number TS9A
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.
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Email: [email protected]
National Semiconductor
Japan Customer Support Center
Fax: 81-3-5639-7507
Email: [email protected]
Tel: 81-3-5639-7560