LM4951
LM4951 Wide Voltage Range 1.8 Watt Audio Amplifier
Literature Number: SNAS244M
LM4951 March 18, 2009
Wide Voltage Range 1.8 Watt Audio Amplifier
General Description
The LM4951 is an audio power amplifier primarily designed
for demanding applications in Portable Handheld devices. It
is capable of delivering 1.8W mono BTL to an 8Ω load, con-
tinuous average power, with less than 1% distortion (THD+N)
from a 7.5VDC power supply.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. The LM4951 does not require boot-
strap capacitors, or snubber circuits.
The LM4951 features a low-power consumption active-low
shutdown mode. Additionally, the LM4951 features an inter-
nal thermal shutdown protection mechanism.
The LM4951 contains advanced pop & click circuitry that
eliminates noises which would otherwise occur during turn-on
and turn-off transitions.
The LM4951 is unity-gain stable and can be configured by
external gain-setting resistors.
Key Specifications
■ Wide Voltage Range 2.7V to 9V
■ Quiescent Power Supply Current
(VDD = 7.5V) 2.5mA (typ)
■ Power Output BTL at 7.5V,
1% THD 1.8W (typ)
■ Shutdown Current 0.01µA (typ)
■ Fast Turn on Time 25ms (typ)
Features
■Pop & click circuitry eliminates noise during turn-on and
turn-off transitions
■Low current, active-low shutdown mode
■Low quiescent current
■Thermal shutdown protection
■Unity-gain stable
■External gain configuration capability
Applications
■Portable Handheld Devices up to 9V
■Cell Phone
■PDA
Typical Application
200942f4
* RC is needed for over/under voltage protection. If inputs are less than VDD +0.3V and greater than –0.3V, and if inputs are
disabled when in shutdown mode, then RC may be shorted.
FIGURE 1. Typical Bridge-Tied-Load (BTL) Audio Amplifier Application Circuit
Boomer® is a registered trademark of National Semiconductor Corporation.
© 2009 National Semiconductor Corporation 200942 www.national.com
LM4951 Wide Voltage Range 1.8 Watt Audio Amplifier
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LM4951
Connection Diagrams
SD Package
20094229
Top View
Order Number LM4951SD
See NS Package Number SDC10A
9 Bump micro SMD Package
20094228
Top View
Order Number LM4951TL, TLX
See NS Package Number TLA09ZZA
* DAP can either be soldered to GND or left floating.
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LM4951
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 9.5V
Storage Temperature −65°C to +150°C
Input Voltage −0.3V to VDD + 0.3V
Power Dissipation (Note 3) Internally limited
ESD Susceptibility (Note 4) 2000V
ESD Susceptibility (Note 5) 200V
Junction Temperature 150°C
Thermal Resistance
θJA (LLP) (Note 3) 52°C/W
See AN-1187 'Leadless Leadframe
Packaging (LLP).'
Operating Ratings
Temperature Range
TMIN ≤ TA ≤ TMAX −40°C ≤ T A ≤ +85°C
Supply Voltage 2.7V ≤ VDD ≤ 9V
Electrical Characteristics VDD = 7.5V (Notes 1, 2)
The following specifications apply for VDD = 7.5V, AV-BTL = 6dB, RL = 8Ω unless otherwise specified. Limits apply for TA = 25°C.
Symbol Parameter Conditions LM4951 Units
(Limits)
Typical
(Note 6)
Limit
(Notes 7, 8)
IDD Quiescent Power Supply Current VIN = 0V, IO = 0A,RL = 8Ω2.5 4.5 mA (max)
ISD Shutdown Current VSHUTDOWN = GND (Note 9) 0.01 5 µA (max)
VOS Offset Voltage 5 30 mV (max)
VSDIH Shutdown Voltage Input High 1.2 V (min)
VSDIL Shutdown Voltage Input Low 0.4 V (max)
Rpulldown Pulldown Resistor on S/D 75 45 kΩ (min)
TWU Wake-up Time CB = 1.0µF 25 35 ms
Tsd Shutdown time CB = 1.0µF 10 ms (max)
TSD Thermal Shutdown Temperature 170 150
190
°C (min)
°C (max)
POOutput Power THD = 1% (max); f = 1kHz
RL = 8Ω Mono BTL 1.8 1.5 W (min)
THD+N Total Harmomic Distortion + Noise PO = 600mWrms; f = 1kHz
AV-BTL = 6dB 0.07 0.5 % (max)
THD+N Total Harmomic Distortion + Noise PO = 600mWrms; f = 1kHz
AV-BTL = 26dB 0.35 %
εOS Output Noise A-Weighted Filter, Ri = Rf = 20kΩ
Input Referred, Note 10 10 µV
PSRR Power Supply Rejection Ratio VRIPPLE = 200mVp-p, f = 217Hz,
CB = 1.0μF, Input Referred 66 56 dB (min)
Electrical Characteristics VDD = 3.3V (Notes 1, 2)
The following specifications apply for VDD = 3.3V, AV-BTL = 6dB, RL = 8Ω unless otherwise specified. Limits apply for TA = 25°C.
Symbol Parameter Conditions LM4951 Units
(Limits)
Typical
(Note 6)
Limit
(Notes 7, 8)
IDD Quiescent Power Supply Current VIN = 0V, IO = 0A,RL = 8Ω2.5 4.5 mA (max)
ISD Shutdown Current VSHUTDOWN = GND (Note 9) 0.01 2 µA (max)
VOS Offset Voltage 3 30 mV (max)
VSDIH Shutdown Voltage Input High 1.2 V (min)
VSDIL Shutdown Voltage Input Low 0.4 V (max)
TWU Wake-up Time CB = 1.0µF 25 ms (max)
Tsd Shutdown time CB = 1.0µF 10 ms (max)
POOutput Power THD = 1% (max); f = 1kHz
RL = 8Ω Mono BTL 280 230 mW (min)
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LM4951
Symbol Parameter Conditions LM4951 Units
(Limits)
Typical
(Note 6)
Limit
(Notes 7, 8)
THD+N Total Harmomic Distortion + Noise1 PO = 100mWrms; f = 1kHz
AV-BTL = 6dB 0.07 0.5 % (max)
THD+N Total Harmomic Distortion + Noise1 PO = 100mWrms; f = 1kHz
AV-BTL = 26dB 0.35 %
εOS Output Noise A-Weighted Filter, Ri = Rf = 20kΩ
Input Referred, Note 10 10 µV
PSRR Power Supply Rejection Ratio VRIPPLE = 200mVp-p, f = 217Hz,
CB = 1μF, Input Referred 71 61 dB (min)
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 LM4951 typical application
(shown in Figure 1) with VDD = 7.5V, RL = 8Ω mono-BTL operation the max power dissipation is 1.42W. θJA = 73°C/W.
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: 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.
Note 10: Noise measurements are dependent on the absolute values of the closed loop gain setting resistors (input and feedback resistors).
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LM4951
Typical Performance Characteristics
THD+N vs Frequency
VDD = 3.3V, PO = 100mW, AV = 6dB
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THD+N vs Frequency
VDD = 3.3V, PO = 100mW, AV = 26dB
20094202
THD+N vs Frequency
VDD = 5V, PO = 400mW, AV = 6dB
20094203
THD+N vs Frequency
VDD = 5V, PO = 400mW, AV = 26dB
20094204
THD+N vs Frequency
VDD = 7.5V, PO = 600mW, AV = 6dB
20094205
THD+N vs Frequency
VDD = 7.5V, PO = 600mW, AV = 26dB
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LM4951
THD+N vs Output Power
VDD = 3.3V, f = 1kHz, AV = 6dB
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THD+N vs Output Power
VDD = 3.3V, f = 1kHz, AV = 26dB
20094208
THD+N vs Output Power
VDD = 5V, f = 1kHz, AV = 6dB
20094209
THD+N vs Output Power
VDD = 5V, f = 1kHz, AV = 26dB
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THD+N vs Output Power
VDD = 7.5V, f = 1kHz, AV = 6dB
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THD+N vs Output Power
VDD = 7.5V, f = 1kHz, AV = 26dB
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LM4951
Power Supply Rejection vs Frequency
VDD = 3.3V, AV = 6dB, VRIPPLE = 200mVP-P
Input Terminated into 10Ω
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Power Supply Rejection vs Frequency
VDD = 3.3V, AV = 26dB, VRIPPLE = 200mVP-P
Input Terminated into 10Ω
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Power Supply Rejection vs Frequency
VDD = 5V, AV = 6dB, VRIPPLE = 200mVP-P
Input Terminated into 10Ω
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Power Supply Rejection vs Frequency
VDD = 5V, AV = 26dB, VRIPPLE = 200mVP-P
Input Terminated into 10Ω
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Power Supply Rejection vs Frequency
VDD = 7.5V, AV = 6dB, VRIPPLE = 200mVP-P
Input Terminated into 10Ω
20094217
Power Supply Rejection vs Frequency
VDD = 7.5V, AV = 26dB, VRIPPLE = 200mVP-P
Input Terminated into 10Ω
20094218
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LM4951
Noise Floor
VDD = 3.3V, AV = 6dB, Ri = Rf = 20kΩ
BW < 80kHz, A-weighted
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Noise Floor
VDD = 3V, AV = 26dB, Ri = 20kΩ, Rf = 200kΩ
BW < 80kHz, A-weighted
20094220
Noise Floor
VDD = 5V, AV = 6dB, Ri = Rf = 20kΩ
BW < 80kHz, A-weighted
20094221
Noise Floor
VDD = 5V, AV = 26dB, Ri = 20kΩ, Rf = 200kΩ
BW < 80kHz, A-weighted
20094222
Noise Floor
VDD = 7.5V, AV = 6dB, Ri = Rf = 20kΩ
BW < 80kHz, A-weighted
20094223
Noise Floor
VDD = 7.5V, AV = 26dB, Ri = 20kΩ, Rf = 200kΩ
BW < 80kHz, A-weighted
20094224
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LM4951
Power Dissipation
vs Output Power
VDD = 3.3V, RL = 8Ω, f = 1kHz
20094225
Power Dissipation
vs Output Power
VDD = 7.5V, RL = 8Ω, f = 1kHz
20094226
Supply Current
vs Supply Voltage
RL = 8Ω, VIN = 0V, Rsource = 50Ω
20094227
Clipping Voltage vs Supply Voltage
RL = 8Ω,
from top to bottom: Negative Voltage Swing; Positive
Voltage Swing
200942e9
Output Power vs Supply Voltage
RL = 8Ω,
from top to bottom: THD+N = 10%, THD+N = 1%
200942f0
Output Power vs Load Resistance
VDD = 3.3V, f = 1kHz
from top to bottom: THD+N = 10%, THD+N = 1%
200942f1
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LM4951
Output Power vs Load Resistance
VDD = 7.5V, f = 1kHz
from top to bottom: THD+N = 10%, THD+N = 1%
200942f2
Frequency Response vs Input Capacitor Size
RL = 8Ω
from top to bottom: Ci = 1.0µF, Ci = 0.39µF, Ci = 0.039µF
200942f3
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LM4951
Application Information
HIGH VOLTAGE BOOMER
Unlike previous 5V Boomer® amplifiers, the LM4951 is de-
signed to operate over a power supply voltages range of 2.7V
to 9V. Operating on a 7.5V power supply, the LM4951 will
deliver 1.8W into an 8Ω BTL load with no more than 1% THD
+N.
BRIDGE CONFIGURATION EXPLANATION
As shown in Figure 1, the LM4951 consists of two operational
amplifiers that drive a speaker connected between their out-
puts. The value of input and feedback resistors determine the
gain of each amplifier. External resistors Ri and Rf set the
closed-loop gain of AMPA, whereas two 20kΩ internal resis-
tors set AMPB's gain to -1. The LM4951 drives a load, such
as a speaker, connected between the two amplifier outputs,
VO+ and VO -. Figure 1 shows that AMPA's output serves as
AMPB's input. This results in both amplifiers producing signals
identical in magnitude, but 180° out of phase. Taking advan-
tage of this phase difference, a load is placed between
AMPA and AMPB and driven differentially (commonly referred
to as "bridge mode"). This results in a differential, or BTL, gain
of
AVD = 2(Rf / Ri) (1)
Bridge mode amplifiers are different from single-ended am-
plifiers that drive loads connected between a single amplifier's
output and ground. For a given supply voltage, bridge mode
has a distinct advantage over the single-ended configuration:
its differential output doubles the voltage swing across the
load. Theoretically, this produces four times the output power
when compared to a single-ended amplifier under the same
conditions. This increase in attainable output power assumes
that the amplifier is not current limited and that the output sig-
nal is not clipped. To ensure minimum output signal clipping
when choosing an amplifier's closed-loop gain, refer to the
AUDIO POWER AMPLIFIER DESIGN section. Under rare
conditions, with unique combinations of high power supply
voltage and high closed loop gain settings, the LM4951 may
exhibit low frequency oscillations.
Another advantage of the differential bridge output is no net
DC voltage across the load. This is accomplished by biasing
AMP1's and AMP2's outputs at half-supply. This eliminates
the coupling capacitor that single supply, single-ended am-
plifiers require. Eliminating an output coupling capacitor in a
typical single-ended configuration forces a single-supply
amplifier's half-supply bias voltage across the load. This in-
creases internal IC power dissipation and may permanently
damage loads such as speakers.
POWER DISSIPATION
Power dissipation is a major concern when designing a suc-
cessful bridged amplifier.
The LM4951's dissipation when driving a BTL load is given
by Equation (2). For a 7.5V supply and a single 8Ω BTL load,
the dissipation is 1.42W.
PDMAX-MONOBTL = 4(VDD) 2 / 2π2RL: Bridge Mode (2)
The maximum power dissipation point given by Equation (2)
must not exceed the power dissipation given by Equation (3):
PDMAX' = (TJMAX - TA) / θJA (3)
The LM4951's TJMAX = 150°C. In the SD package, the
LM4951's θJA is 73°C/W when the metal tab is soldered to a
copper plane of at least 1in2. This plane can be split between
the top and bottom layers of a two-sided PCB. Connect the
two layers together under the tab with an array of vias. At any
given ambient temperature TA, use Equation (3) to find the
maximum internal power dissipation supported by the IC
packaging. Rearranging Equation (3) and substituting
PDMAX for PDMAX' results in Equation (4). This equation gives
the maximum ambient temperature that still allows maximum
stereo power dissipation without violating the LM4951's max-
imum junction temperature.
TA = TJMAX - PDMAX-MONOBTLθJA (4)
For a typical application with a 7.5V power supply and a BTL
8Ω load, the maximum ambient temperature that allows max-
imum stereo power dissipation without exceeding the maxi-
mum junction temperature is approximately 46°C for the TS
package.
TJMAX = PDMAX-MONOBTLθJA + TA(5)
Equation (5) gives the maximum junction temperature
TJMAX. If the result violates the LM4951'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 ambi-
ent temperatures are allowed as output power or duty cycle
decreases.
If the result of Equation (2) is greater than that of Equation (3),
then decrease the supply voltage, increase the load
impedance, or reduce the ambient temperature. Further, en-
sure that speakers rated at a nominal 8Ω do not fall below
6Ω. If these measures are insufficient, a heat sink can be
added to reduce θJA. The heat sink can be created using ad-
ditional 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 pow-
er dissipation information at lower output power levels.
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.
POWER SUPPLY BYPASSING
As with any power amplifier, proper supply bypassing is crit-
ical for low noise performance and high power supply rejec-
tion. 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 im-
prove the supply's transient response. However, their pres-
ence does not eliminate the need for a local 1.0µF tantalum
bypass capacitance connected between the LM4951's supply
pins and ground. Do not substitute a ceramic capacitor for the
tantalum. Doing so may cause oscillation. Keep the length of
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LM4951
leads and traces that connect capacitors between the
LM4951's power supply pin and ground as short as possible.
Connecting a larger capacitor, CBYPASS, between the BY-
PASS pin and ground improves the internal bias voltage's
stability and improves the amplifier's PSRR. The PSRR im-
provements increase as the bypass pin capacitor value in-
creases. 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, de-
pends on desired PSRR requirements, click and pop perfor-
mance (as explained in the section, SELECTING EXTER-
NAL COMPONENTS), system cost, and size constraints.
MICRO-POWER SHUTDOWN
The LM4951 features an active-low micro-power shutdown
mode. When active, the LM4951's micro-power shutdown
feature turns off the amplifier's bias circuitry, reducing the
supply current. The low 0.01µA 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 shut-
down. These include using a single-pole, single-throw switch
(SPST), a microprocessor, or a microcontroller. When using
a switch, connect the SPST switch between the shutdown pin
and VDD. Select normal amplifier operation by closing the
switch. Opening the switch applies GND to the SHUTDOWN
pin activating micro-power shutdwon.The switch and internal
pull-down 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.
SELECTING EXTERNAL COMPONENTS
Input Capacitor Value Selection
Two quantities determine the value of the input coupling ca-
pacitor: the lowest audio frequency that requires amplification
and desired output transient suppression.
As shown in Figure 1, the input resistor (Ri) and the input ca-
pacitor (Ci) produce a high pass filter cutoff frequency that is
found using Equation (6).
fc = 1/2πRiCi(6)
As an example when using a speaker with a low frequency
limit of 50Hz, Ci, using Equation (6) is 0.159µF. The 0.39µF
CINA shown in Figure 1 allows the LM4951 to drive high effi-
ciency, full range speaker whose response extends below
30Hz.
Selecting Value For RC
The LM4951 is designed for very fast turn on time. The Cchg
pin allows the input capacitors (CinA and CinB) to charge
quickly to improve click/pop performance. Rchg1 and Rchg2
protect the Cchg pins from any over/under voltage conditions
caused by excessive input signal or an active input signal
when the device is in shutdown. The recommended value for
Rchg1 and Rchg2 is 1kΩ. If the input signal is less than VDD
+0.3V and greater than -0.3V, and if the input signal is dis-
abled when in shutdown mode, Rchg1 and Rchg2 may be
shorted out.
OPTIMIZING CLICK AND POP REDUCTION
PERFORMANCE
The LM4951 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 LM4951's internal amplifiers are configured as
unity gain buffers. An internal current source charges the ca-
pacitor 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 volt-
age on the bypass pin reaches VDD/2. As soon as the voltage
on the bypass pin is stable, there is a delay to prevent unde-
sirable output transients (“click and pops”). After this delay,
the device becomes fully functional.
AUDIO POWER AMPLIFIER DESIGN
Audio Amplifier Design: Driving 1.8W into an 8Ω BTL
The following are the desired operational parameters:
Power Output 1.8WRMS
Load Impedance 8Ω
Input Level 0.3VRMS (max)
Input Impedance 20kΩ
Bandwidth 50Hz–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 (7), 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 Volt-
age in the Typical Performance Characteristics curves,
must be added to the result obtained by Equation (7). The
result is Equation (8).
(7)
VDD = VOUTPEAK + VODTOP + VODBOT (8)
The commonly used 7.5V supply voltage easily meets this.
The additional voltage creates the benefit of headroom, al-
lowing the LM4951 to produce peak output power in excess
of 1.8W 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 LM4951's
power dissipation requirements, the minimum differential gain
needed to achieve 1.8W dissipation in an 8Ω BTL load is
found using Equation (9).
(9)
Thus, a minimum gain of 12.6 allows the LM4951's to reach
full output swing and maintain low noise and THD+N perfor-
mance. For this example, let AV-BTL = 13. The amplifier's
overall BTL gain is set using the input (Ri) and feedback (Rf)
resistors of the first amplifier in the series BTL configuration.
Additionaly, AV-BTL is twice the gain set by the first amplifier's
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LM4951
Ri and Rf. With the desired input impedance set at 20kΩ, the
feedback resistor is found using Equation (10).
Rf / Ri = AV-BTL / 2 (10)
The value of Rf is 130kΩ (choose 191kΩ, the closest value).
The nominal output power is 1.8W.
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 re-
sponse 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 ±0.25dB-de-
sired limit. The results are an
fL = 50Hz / 5 = 10Hz (11)
and an
fL = 20kHz x 5 = 100kHz (12)
As mentioned in the SELECTING EXTERNAL COMPO-
NENTS section, Ri and Ci create a highpass filter that sets the
amplifier's lower bandpass frequency limit. Find the coupling
capacitor's value using Equation (13).
Ci = 1 / 2πRifL(13)
The result is
1 / (2πx20kΩx10Hz) = 0.795µF
Use a 0.82µF capacitor, the closest standard value.
The product of the desired high frequency cutoff (100kHz in
this example) and the differential gain AVD, determines the
upper passband response limit. With AVD = 7 and fH = 100kHz,
the closed-loop gain bandwidth product (GBWP) is 700kHz.
This is less than the LM4951's 3.5MHz GBWP. With this mar-
gin, the amplifier can be used in designs that require more
differential gain while avoiding performance restricting band-
width limitations.
RECOMMENDED PRINTED CIRCUIT BOARD LAYOUT
Figures 2–4 show the recommended two-layer PC board lay-
out that is optimized for the SD10A. This circuit is designed
for use with an external 7.5V supply 8Ω (min) speakers.
These circuit boards are easy to use. Apply 7.5V and ground
to the board's VDD and GND pads, respectively. Connect a
speaker between the board's OUTA and OUTB outputs.
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LM4951
Demonstration Board Layout
200942f8
FIGURE 2. Recommended TS SE PCB Layout:
Top Silkscreen
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FIGURE 3. Recommended TS SE PCB Layout:
Top Layer
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LM4951
200942f6
FIGURE 4. Recommended TS SE PCB Layout:
Bottom Layer
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LM4951
Revision History
Rev Date Description
1.0 8/25/04 Initial WEB.
1.1 10/19/05 Added the micro SMD pkg, then WEB.
1.2 08/30/06 Added the Limit value (=35) on the Twu
(7.5V Elect Char table), then WEB.
1.3 09/11/06 Added the “Selecting Value For Rc,
then WEB.
1.4 05/21/07 Fixed a typo ( X3 value = 0.600±0.075)
instead of (X3 = 0.600±0.75).
1.5 03/18/09 Text edits.
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LM4951
Physical Dimensions inches (millimeters) unless otherwise noted
Order Number LM4951SD
NS Package Number SDC10A
Order Number LM4951TL, TLX
NS Package Number TLA09ZZA
X1 = 1.463±0.03, X2 = 1.463±0.03, X3 = 0.600±0.075
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LM4951
Notes
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LM4951
Notes
LM4951 Wide Voltage Range 1.8 Watt Audio Amplifier
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