LM48410
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LM48410
SNAS403E – FEBRUARY 2007 – REVISED MAY 2013
Low EMI, Filterless, 2.3W Stereo Class D Audio
Power Amplifier with 3D Enhancement
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FEATURES
DESCRIPTION
•
The LM48410 is a single supply, high efficiency,
2.3W/channel, filterless switching audio amplifier. A
low noise PWM architecture eliminates the output
filter, reducing external component count, board area
consumption, system cost, and simplifying design. A
selectable spread spectrum modulation scheme
suppresses RF emissions, further reducing the need
for output filters.
1
2
•
•
•
•
•
•
•
•
•
•
Selectable Spread Spectrum Mode Reduces
EMI
Output Short Circuit Protection
Stereo Class D Operation
No Output Filter Required
3D Enhancement
Logic Selectable Gain
Independent Channel Shutdown Controls
Minimum External Components
Click and Pop Suppression
Micro-Power Shutdown
Available in Space-Saving 4mm x 4mm WQFN
Package
APPLICATIONS
•
•
•
Mobile Phones
PDAs
Laptops
KEY SPECIFICATIONS
•
•
•
•
•
•
•
Quiescent Power Supply Current at 3.6V
supply 4mA
Power Output at VDD = 5V, RL = 4Ω, THD ≤ 10%
2.3W (typ)
Power Output at VDD = 5V, RL = 8Ω, THD ≤ 10%
1.5W (typ)
Shutdown current 0.03μA (typ)
Efficiency at 3.6V, 100mW into 8Ω 80% (typ)
Efficiency at 3.6V, 500mW into 8Ω 85% (typ)
Efficiency at 5V, 1W into 8Ω 86% (typ)
The LM48410 is designed to meet the demands of
mobile phones and other portable communication
devices. Operating from a single 5V supply, the
device is capable of delivering 2.3W/channel of
continuous output power to a 4Ω load with less than
10% THD+N. Flexible power supply requirements
allow operation from 2.4V to 5.5V. The LM48410
offers two logic selectable modulation schemes, fixed
frequency mode, and an EMI reducing spread
spectrum mode.
The LM48410 features high efficiency compared with
conventional Class AB amplifiers. When driving an
8Ω speaker from a 3.6V supply, the device operates
with 85% efficiency at PO = 500mW/Ch. Four gain
options are pin selectable through the G0 and G1
pins. The LM48410 also includes 3D audio
enhancement that improves stereo sound quality. In
devices where the left and right speakers are in close
proximity, 3D enhancement affects channel
specialization, widening the perceived soundstage.
Output short circuit protection prevents the device
from being damaged during fault conditions. Superior
click and pop suppression eliminates audible
transients on power-up/down and during shutdown.
Independent left/right shutdown controls maximizes
power savings in mixed mono/stereo applications.
1
2
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2007–2013, Texas Instruments Incorporated
LM48410
SNAS403E – FEBRUARY 2007 – REVISED MAY 2013
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EMI Plot
Typical Application
+2.5V to +5.5V
C3D+
R3D+
3DL+
3DR+
CS
CS
VDD PVDD PVDD
CIN
OUTRA
INR+
INR-
GAIN
MODULATOR
HBRIDGE
OUTRB
CIN
SDR
G0
3D
G1
OSCILLATOR
SDL
CIN
OUTLA
INL+
INLCIN
GAIN
MODULATOR
HBRIDGE
OUTLB
3DEN
SS/FF
3DL-
R3D-
3DR-
GND
PGND
C3D-
Figure 1. Typical Audio Amplifier Application Circuit
2
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3DR-
G0
VDD
PVDD
OUTRA
OUTRB
Connection Diagram
24
23
22
21
20
19
17
GND
INR-
3
16
SDR
3DEN
4
15
SS/FF
INL-
5
14
SDL
INL+
6
13
PGND
7
8
9
10
11
12
OUTLB
2
OUTLA
INR+
PVDD
PGND
G1
18
3DL-
1
3DL+
3DR+
Figure 2. 24-Lead WQFN
4mm x 4mm x 0.8mm - Top View
See RTW0024A Package
PIN DESCRIPTIONS
Pin
Name
Description
1
3DR+
Right Channel non-inverting 3D connection. Connect to 3DL+ through
C3D+ and R3D+
2
INR+
Right Channel Non-Inverting Input
3
INR-
Right Channel Inverting Input
4
3DEN
3D Enable Input
5
INL-
Left Channel Inverting Input
6
INL+
Left Channel Non-Inverting Input
7
3DL+
Left Channel non-inverting 3D connection. Connect to 3DR+ through C3D+
and R3D+
8
3DL-
Left Channel inverting 3D connection. Connect to 3DR- through C3D-and
R3D-
9
G1
Gain Select Input 1
10, 21
PVDD
11
OUTLA
Speaker Power Supply
Left Channel Non-Inverting Output
12
OUTLB
Left Channel Inverting Output
13, 18
PGND
Power Ground
14
SDL
15
SS/FF
16
SDR
Right Channel Active Low Shutdown. Connect to VDD for normal
operation. Connect to GND to disable the right channel.
17
GND
Ground
19
OUTRB
Left Channel Active Low Shutdown. Connect to VDD for normal operation.
Connect to GND to disable the left channel.
Modulation Mode Select. Connect to VDD for spread spectrum mode.
Connect to GND for fixed frequency mode
Right Channel Inverting Output
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PIN DESCRIPTIONS (continued)
Pin
Name
20
OUTRA
Description
22
VDD
Power Supply
23
G0
Gain Select Input 0
24
3DR-
Right Channel Non-Inverting Output
Right Channel inverting 3D connection. Connect to 3DL- through C3D-and
R3D-
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
Absolute Maximum Ratings (1) (2) (3)
Supply Voltage (1)
6.0V
−65°C to +150°C
Storage Temperature
Input Voltage
–0.3V to VDD +0.3V
Power Dissipation (4)
Internally Limited
(5)
2000V
ESD Susceptibility
ESD Susceptibility (6)
200V
Junction Temperature
150°C
Thermal Resistance
(1)
(2)
(3)
(4)
(5)
(6)
θJC
5.3°C/W
θJA
36.5°C/W
All voltages are measured with respect to the ground pin, unless otherwise specified.
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 ensure specific performance limits. Electrical Characteristics state DC and AC electrical
specifications under particular test conditions which ensure specific performance limits. This assumes that the device is within the
Operating Ratings. Specifications are not ensured for parameters where no limit is given, however, the typical value is a good indication
of device performance.
å
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 = (TJMAX – TA)/ θJA or the number given in Absolute Maximum Ratings,
whichever is lower.
Human body model, 100pF discharged through a 1.5kΩ resistor.
Machine Model, 220pF–240pF discharged through all pins.
Operating Ratings (1) (2)
Temperature Range TMIN ≤ TA ≤ TMAX
−40°C ≤ TA ≤ 85°C
2.4V ≤ VDD ≤ 5.5V
Supply Voltage (VDD, PVDD)
(1)
(2)
4
All voltages are measured with respect to the ground pin, unless otherwise specified.
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 ensure specific performance limits. Electrical Characteristics state DC and AC electrical
specifications under particular test conditions which ensure specific performance limits. This assumes that the device is within the
Operating Ratings. Specifications are not ensured for parameters where no limit is given, however, the typical value is a good indication
of device performance.
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Electrical Characteristics VDD = PVDD = 3.6V (1) (2)
The following specifications apply for AV = 6dB, RL = 15μH + 8Ω + 15μH, SS/FF = VDD = (Spread Spectrum mode), f = 1kHz,
unless otherwise specified. Limits apply for TA = 25°C.
Symbol
VOS
Parameter
Differential Output Offset Voltage
Conditions
VIN = 0, VDD = 2.4V to 5.0V
LM48410
Typical (3)
Limit (4) (5)
5
Units
(Limits)
mV
VIN = 0, No Load
IDD
Quiescent Power Supply Current
Both channels active, VDD = 3.6V
4
6.5
mA (max)
VDD = 5V
5
8.5
mA (max)
1
μA (max)
ISD
Shutdown Current
VIH
Logic Input High Voltage
1.4
V (min)
VIL
Logic Input Low Voltage
0.4
V (max)
TWU
Wake Up Time
fSW
Switching Frequency
VSDL = VSDR = GND
4
SS/FF = VDD (Spread Spectrum)
300
SS/FF = GND (Fixed Frequency)
300
G0, G1 = GND, RL = ∞
AV
RIN
(1)
(2)
(3)
(4)
(5)
0.03
6
kHz (max)
kHz
5.5
dB (min)
6.5
dB (max)
11.5
dB (min)
12.5
dB (max)
G0 = VDD, G1 = GND
12
G0 = GND, G1 = VDD
18
G0, G1 = VDD
24
AV = 6dB
160
kΩ
AV = 12dB
80
kΩ
AV = 18dB
40
kΩ
AV = 24dB
20
kΩ
Gain
Input Resistance
ms
390
17.5
dB (min)
18.5
dB (max)
23.5
dB (min)
24.5
dB (max)
All voltages are measured with respect to the ground pin, unless otherwise specified.
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 ensure specific performance limits. Electrical Characteristics state DC and AC electrical
specifications under particular test conditions which ensure specific performance limits. This assumes that the device is within the
Operating Ratings. Specifications are not ensured for parameters where no limit is given, however, the typical value is a good indication
of device performance.
Typicals are measured at 25°C and represent the parametric norm.
Limits are specified to TI's AOQL (Average Outgoing Quality Level).
Datasheet min/max specification limits are specified by design, test, or statistical analysis.
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Electrical Characteristics VDD = PVDD = 3.6V(1)(2) (continued)
The following specifications apply for AV = 6dB, RL = 15μH + 8Ω + 15μH, SS/FF = VDD = (Spread Spectrum mode), f = 1kHz,
unless otherwise specified. Limits apply for TA = 25°C.
Symbol
Parameter
Conditions
LM48410
Typical (3)
Limit (4) (5)
Units
(Limits)
RL = 15μH + 4Ω + 15μH, THD ≤ 10%
f = 1kHz, 22kHz BW
VDD = 5V
2.3
W
VDD = 3.6V
1.14
W
VDD = 2.5V
490
mW
RL = 15μH + 8Ω + 15μH, THD ≤ 10%
f = 1kHz, 22kHz BW
PO
Output Power (Per Channel)
VDD = 5V
1.5
VDD = 3.6V
740
VDD = 2.5V
330
W
600
mW (min)
mW
RL = 15μH + 4Ω + 15μH, THD ≤ 1%
f = 1kHz, 22kHz BW
VDD = 5V
1.85
W
VDD = 3.6V
940
mW
V DD = 2.5V
400
mW
VDD = 5V
1.18
W
VDD = 3.6V
580
mW
VDD = 2.5V
270
mW
PO = 500mW/Ch, f = 1kHz, RL = 8Ω
0.025
%
PO = 300mW/Ch, f = 1kHz, RL = 8Ω
0.07
%
70
68
dB
dB
RL = 15μH + 8Ω + 15μH, THD = 1%
f = 1kHz, 22kHz BW
THD+N
PSRR
Total Harmonic Distortion
Power Supply Rejection Ratio
VRIPPLE = 200mVP-P Sine,
Inputs AC GND,
CIN = 1μF, input referred
fRipple = 217Hz
fRipple = 1kHz,
CMRR
Common Mode Rejection Ratio
VRIPPLE = 1VP-P
fRIPPLE = 217Hz
65
dB
η
Efficiency
PO = 1W/Ch, f = 1kHz,
RL = 8Ω, VDD = 5V
86
%
Xtalk
Crosstalk
PO = 500mW/Ch, f = 1kHz
82
dB
SNR
Signal to Noise Ratio
VDD = 5V, PO = 1W
Fixed Frequency Mode
88
dB
εOS
Output Noise
Input referred, Fixed Frequency
Mode
A-Weighted Filter
28
μV
6
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Typical Performance Characteristics
THD+N vs Output Power
f = 1kHz, AV = 6dB, RL = 8Ω
100
THD+N vs Output Power
f = 1kHz, AV = 6dB, RL = 4Ω
100
VDD = 5V
V DD = 5V
10
VDD = 3.6V
THD+N (%)
THD+N (%)
10
VDD = 2.5V
1
VDD = 3.6V
1
V DD = 2.5V
0.1
0.1
0.01
0.001
0.01
0.1
1
0.01
0.001
10
0.1
1
10
OUTPUT POWER (W)
Figure 4.
THD+N vs Frequency
VDD = 2.5V, POUT = 100mW, RL = 8Ω
THD+N vs Frequency
VDD = 3.6V, POUT = 250mW, RL = 8Ω
100
100
10
10
1
0.1
0.01
1
0.1
0.01
0.001
20
100
1k
10k 20k
0.001
20
100
1k
10k 20k
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 5.
Figure 6.
THD+N vs Frequency
VDD = 5V, POUT = 375mW, RL = 8Ω
THD+N vs Frequency
VDD = 2.5V, POUT = 100mW, RL = 4Ω
100
100
10
10
THD+N (%)
THD+N (%)
0.01
Figure 3.
THD+N (%)
THD+N (%)
OUTPUT POWER (W)
1
0.1
0.01
0.001
20
1
0.1
0.01
100
1k
10k 20k
0.001
20
100
1k
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 7.
Figure 8.
10k 20k
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Typical Performance Characteristics (continued)
THD+N vs Frequency
VDD = 5V, POUT = 375mW, RL = 4Ω
100
100
10
10
THD+N (%)
THD+N (%)
THD+N vs Frequency
VDD = 3.6V, POUT = 250mW, RL = 4Ω
1
0.1
0.01
1
0.1
0.01
0.001
20
100
1k
0.001
20
10k 20k
1k
10k 20k
FREQUENCY (Hz)
Figure 9.
Figure 10.
Efficiency vs Output Power
RL = 4Ω, f = 1kHz
Efficiency vs Output Power
RL = 8Ω, f = 1kHz
100
100
VDD = 5V
90
90
80
EFFICIENCY (%)
80
EFFICIENCY (%)
100
FREQUENCY (Hz)
70
VDD = 3.6V
60
VDD = 2.5V
50
40
50
40
30
20
20
10
10
0
0
500
1000
1500
VDD = 3.6V
60
30
0
VDD = 5V
70
2000
VDD = 2.5V
0
300
600
900
1200
1500
OUTPUT POWER (mW)
OUTPUT POWER (mW)
Figure 11.
Figure 12.
Power Dissipation vs Output Power
RL = 4Ω, f = 1kHz
Power Dissipation vs Output Power
RL = 8Ω, f = 1kHz
1500
500
1200
VDD = 5V
VDD = 2.5V
900
VDD = 3.6V
600
300
0
8
POWER DISSIPATION (mW)
POWER DISSIPATION (mW)
450
400
1000
2000
3000
VDD = 2.5V
300
VDD = 3.6V
250
200
150
100
50
POUT = POUTL + POUTR
0
VDD = 5V
350
4000
POUT = POUTL + POUTR
0
0
500
1000
1500
2000
2500
OUTPUT POWER (mW)
OUTPUT POWER (mW)
Figure 13.
Figure 14.
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Typical Performance Characteristics (continued)
Output Power vs Supply Voltage
RL = 4Ω, f = 1kHz
Output Power vs Supply Voltage
RL = 8Ω, f = 1kHz
2000
3000
OUTPUT POWER (mW)
OUTPUT POWER (mW)
2500
2000
THD+N = 10%
1500
THD+N = 1%
1000
1500
THD+N = 10%
1000
THD+N = 1%
500
500
0
2.5
0
3
3.5
4
4.5
5
2.5
5.5
3
4
4.5
5
5.5
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
Figure 15.
Figure 16.
PSRR vs Frequency
VDD = 3.6V, VRIPPLE= 200mVP-P, RL = 8Ω
Crosstalk vs Frequency
VDD = 3.6V, VRIPPLE = 1VP-P, RL = 8Ω
0
0
-10
-10
-20
CROSSTALK (dB)
-20
PSRR(dB)
3.5
-30
-40
-50
-60
-30
-40
-50
-60
-70
-80
-70
-80
20
-90
100
1k
-100
20
10k 20k
100
FREQUENCY (Hz)
Figure 17.
Figure 18.
CMRR vs Frequency
VDD = 3.6V, VCM = 1VP-P, RL = 8Ω
Supply Current vs Supply Voltage
No Load
-10
7
SUPPLY CURRENT (mA)
8
-20
CMRR (dB)
10k 20k
FREQUENCY (Hz)
0
-30
-40
-50
-60
6
5
4
3
2
1
-70
-80
20
1k
100
1k
10k 20k
0
2.5
3
3.5
4
4.5
FREQUENCY (Hz)
SUPPLY VOLTAGE (V)
Figure 19.
Figure 20.
5
5.5
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Typical Performance Characteristics (continued)
Fixed Frequency FFT
VDD = 3.6V
0 dB
Spread Spectrum FFT
VDD = 3.6V
0
0 dB
-10
-10
-20
-20
-30
-30
-40
-40
-50
-50
-60
-60
-70
-70
-80
-80
-90
-90
-100
20 Hz
10 MHz
-100
20 Hz
Figure 21.
10
0
10 MHz
Figure 22.
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APPLICATION INFORMATION
GENERAL AMPLIFIER FUNCTION
The LM48410 stereo Class D audio power amplifier features a filterless modulation scheme that reduces external
component count, conserving board space and reducing system cost. The outputs of the device transition from
VDD to GND with a 300kHz switching frequency. With no signal applied, the outputs switch with a 50% duty cycle,
in phase, causing the two outputs to cancel. This cancellation results in no net voltage across the speaker, thus
there is no current to the load in the idle state.
When an input signal is applied, the duty cycle (pulse width) of the LM48410 output's change. For increasing
output voltage, the duty cycle of one side of each output increases, while the duty cycle of the other side of each
output decreases. For decreasing output voltages, the converse occurs. The difference between the two pulse
widths yields the differential output voltage.
FIXED FREQUENCY MODE
The LM48410 features two modulations schemes, a fixed frequency mode and a spread spectrum mode. Select
the fixed frequency mode by setting SS/FF = GND. In fixed frequency mode, the amplifier outputs switch at a
constant 300kHz. In fixed frequency mode, the output spectrum consists of the fundamental and its associated
harmonics (see Typical Performance Characteristics).
SPREAD SPECTRUM
The logic selectable spread spectrum mode eliminates the need for output filters, ferrite beads or chokes. In
spread spectrum mode, the switching frequency varies randomly by 30% about a 300kHz center frequency,
reducing the wideband spectral content and improving EMI emissions radiated by the speaker and associated
cables and traces. A fixed frequency class D exhibits large amounts of spectral energy at multiples of the
switching frequency. The spread spectrum architecture of the LM48410 spreads the same energy over a larger
bandwidth (See Typical Performance Characteristics). The cycle-to-cycle variation of the switching period does
not affect the audio reproduction, efficiency, or PSRR. Set SS/FF = VDD for spread spectrum mode.
DIFFERENTIAL AMPLIFIER EXPLANATION
As logic supplies continue to shrink, system designers are increasingly turning to differential analog signal
handling to preserve signal to noise ratios with restricted voltage swings. The LM48410 features two fully
differential speaker amplifiers. A differential amplifier amplifies the difference between the two input signals.
Traditional audio power amplifiers have typically offered only single-ended inputs resulting in a 6dB reduction of
SNR relative to differential inputs. The LM48410 also offers the possibility of DC input coupling which eliminates
the input coupling capacitors. A major benefit of the fully differential amplifier is the improved common mode
rejection ratio (CMRR) over single-ended input amplifiers. The increased CMRR of the differential amplifier
reduces sensitivity to ground offset related noise injection, especially important in noisy systems.
POWER DISSIPATION AND EFFICIENCY
The major benefit of a Class D amplifier is increased efficiency versus a Class AB. The efficiency of the
LM48410 is attributed to the region of operation of the transistors in the output stage. The Class D output stage
acts as current steering switches, consuming negligible amounts of power compared to a Class AB amplifier.
Most of the power loss associated with the output stage is due to the IR loss of the MOSFET on-resistance,
along with switching losses due to gate charge.
SHUTDOWN FUNCTION
The LM48410 features independent left and right channel shutdown controls, allowing each channel to be
disabled independently. SDR controls the right channel, while SDL controls the left channel. Driving either low
disables the corresponding channel, reducing supply current to 0.1µA.
It is best to switch between ground and VDD for minimum current consumption while in shutdown. The LM48410
may be disabled with shutdown voltages in between GND and VDD, the idle current will be greater than the
typical 0.1μA value.
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The LM48410 shutdown inputs have internal pulldown resistors. The purpose of these resistors is to eliminate
any unwanted state changes when SD is floating. To minimize shutdown current, SD should be driven to GND or
left floating. If SD is not driven to GND or floating, an increase in shutdown supply current will be noticed.
PROPER SELECTION OF EXTERNAL COMPONENTS
Power Supply Bypassing/Filtering
Proper power supply bypassing is important for low noise performance and high PSRR. Place the supply bypass
capacitor as close to the device as possible. Typical applications employ a voltage regulator with 10µF and 0.1µF
bypass capacitors that increase supply stability. These capacitors do not eliminate the need for bypassing of the
LM48410 supply pins. A 1µF capacitor is recommended.
Input Capacitor Slection
Input capacitors may be required for some applications, or when the audio source is single-ended. Input
capacitors block the DC component of the audio signal, eliminating any conflict between the DC component of
the audio source and the bias voltage of the LM48410. The input capacitors create a high-pass filter with the
input resistance RIN. The -3dB point of the high-pass filter is found using Equation 1 below.
f = 1 / 2πRINCIN
(1)
The values for RIN can be found in the Electrical Characteristics table for each gain setting.
The input capacitors can also be used to remove low frequency content from the audio signal. Small speakers
cannot reproduce, and may even be damaged by low frequencies. High-pass filtering the audio signal helps
protect the speakers. When the LM48410 is using a single-ended source, power supply noise on the ground is
seen as an input signal. Setting the high-pass filter point above the power supply noise frequencies, 217 Hz in a
GSM phone, for example, filters out the noise such that it is not amplified and heard on the output. Capacitors
with a tolerance of 10% or better are recommended for impedance matching and improved CMRR and PSRR.
3D Enhancement
The LM48410 features TI’s 3D enhancement effect that widens the perceived soundstage of a stereo audio
signal. The 3D enhancement increases the apparent stereo channel separation, improving audio reproduction
whenever the left and right speakers are too close to one another.
An external RC network shown in Figure 1 is required to enable the 3D effect. Because the LM48410 is a fully
differential amplifier, there are two separate RC networks, one for each stereo input pair (INL+ and INR+, and
INL- and INR-). Set 3DEN high to enable the 3D effect. Set 3DEN low to disable the 3D effect.
The 3D RC network acts as a high pass filter. The amount of the 3D effect is set by the R3D resistor. Decreasing
the value of R3D increases the 3D effect. The C3D capacitor sets the frequency at which the 3D effect occurs.
Increasing the value of C3D decreases the low frequency cutoff point, extending the 3D effect over a wider
bandwidth. The low frequency cutoff point is given by:
f3D(–3dB) = 1 / 2π(R3D)(C3D)
(2)
Enabling the 3D effect increase the gain by a factor of (1+20kΩ/R3D). Setting R3D to 20kΩ results in a gain
increase of 6dB whenever the 3D effect is enabled. In fully differential configuration, the component values of the
two RC networks must be identical. Any component variations can affect the sound quality of the 3D effect. In
single-ended configuration, only the RC network of the input pairs being driven by the audio source needs to be
connected. For instance, if audio is applied to INR+ and INL+, then a 3D network must be connected between
3DL+ and 3DR+. 3DL- and 3DR- can be left unconnected.
12
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AUDIO AMPLIFIER GAIN SETTING
The LM48410 features four internally configured gain settings. The device gain is selected through the two logic
inputs, G0 and G1. The gain settings are as shown in the following table.
LOGIC INPUT
GAIN
G1
G0
V/V
dB
0
0
2
6
0
1
4
12
1
0
8
18
1
1
16
24
SINGLE-ENDED AUDIO AMPLIFIER CONFIGURATION
The LM48410 is compatible with single-ended sources. When configured for single-ended inputs, input
capacitors must be used to block and DC component at the input of the device. Figure 23 shows the typical
single-ended applications circuit.
INL+
INL-
GAIN
CONTROL
INR+
INR-
Figure 23. Single-Ended Circuit Diagram
PCB LAYOUT GUIDELINES
As output power increases, interconnect resistance (PCB traces and wires) between the amplifier, load and
power supply create a voltage drop. The voltage loss due to the traces between the LM48410 and the load
results in lower output power and decreased efficiency. Higher trace resistance between the supply and the
LM48410 has the same effect as a poorly regulated supply, increasing ripple on the supply line, and reducing
peak output power. The effects of residual trace resistance increases as output current increases due to higher
output power, decreased load impedance or both. To maintain the highest output voltage swing and
corresponding peak output power, the PCB traces that connect the output pins to the load and the supply pins to
the power supply should be as wide as possible to minimize trace resistance.
The use of power and ground planes will give the best THD+N performance. In addition to reducing trace
resistance, the use of power planes creates parasitic capacitors that help to filter the power supply line.
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The inductive nature of the transducer load can also result in overshoot on one or both edges, clamped by the
parasitic diodes to GND and VDD in each case. From an EMI standpoint, this is an aggressive waveform that can
radiate or conduct to other components in the system and cause interference. In is essential to keep the power
and output traces short and well shielded if possible. Use of ground planes beads and micros-strip layout
techniques are all useful in preventing unwanted interference.
As the distance from the LM48410 and the speaker increases, the amount of EMI radiation increases due to the
output wires or traces acting as antennas. An antenna becomes a more efficient radiator with lenth. Ferrite chip
inductors places close to the LM48410 outputs may be needed to reduce EMI radiation.
EXPOSED-DAP MOUNTING CONSIDERATIONS
The LM48410 WQFN package features an exposed thermal pad on its underside (DAP, or die attach paddle).
The exposed DAP lowers the package’s thermal resistance by providing a direct heat conduction path from the
die to the printed circuit board. Connect the exposed thermal pad to GND though a large pad and multiple vias to
a GND plane on the bottom of the PCB.
Bill of Materials
Table 1. LM48410SQ Demo Board Bill of Materials
Qty
C1–C4
4
1μF±10%, 16V X7R ceramic
capacitors (1206)
Panasonic
ECJ-3YB1C105K
C5–C9
5
1μF±10%, 16V X7R ceramic
capacitors (603)
Panasonic
ECJ-1VB1C105K
C10
1
1μF±10%, 16V X7R tantalum
capacitors (B-case))
AVX
R1, R2
2
82kΩ±5% resistor (603)
R3, R4
2
100kΩ potentiometer
T1, T2
2
Common mode choke, A1, 800Ω
at 100HHz
JU1–JU6
6
3–pin header
U1
14
Description
Recommended
Manufacturer
Designation
LM48410SQ (24–pin SQA, 4mm
x 4mm x 0.8mm)
Part Number
TPSB106K016R0800
ST4B104CT
TDK
ACM4532–801
Texas Instruments
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LM48410 Demonstration Board Schematic Diagram
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Demoboard PCB Layout
16
Figure 24. Top Silkscreen
Figure 25. Top Soldermask
Figure 26. Top Layer
Figure 27. Layer 2
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Figure 28. Layer 3
Figure 29. Bottom Layer
Figure 30. Bottom Silkscreen
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REVISION HISTORY
Rev
Date
1.0
02/21/07
Initial release.
Description
1.1
03/19/07
Text edits.
1.2
07/11/07
Added the demo boards and schematic diagram.
1.3
02/22/08
Fixed the PID (product folder).
1.4
04/29/08
Text edits.
1.5
07/03/08
Text edits (under SHUTDOWN FUNCTION).
Changes from Revision D (May 2013) to Revision E
•
18
Page
Changed layout of National Data Sheet to TI format .......................................................................................................... 17
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PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
LM48410SQ/NOPB
ACTIVE
WQFN
RTW
24
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 85
L48410
LM48410SQX/NOPB
ACTIVE
WQFN
RTW
24
4500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 85
L48410
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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