LM4952
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SNAS230A – AUGUST 2004 – REVISED MAY 2013
LM4952 Boomer™ Audio Power Amplifier Series 3.1W Stereo-SE Audio Power Amplifier
with DC Volume Control
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FEATURES
DESCRIPTION
•
The LM4952 is a dual audio power amplifier primarily
designed for demanding applications in flat panel
monitors and TV's. It is capable of delivering 3.1
watts per channel to a 4Ω single-ended load with less
than 1% THD+N when powered by a 12VDC power
supply.
1
23
•
•
•
•
•
Pop & Click Circuitry Eliminates Noise During
Turn-on and Turn-off Transitions
Low Current, Active-low Shutdown Mode
Low Quiescent Current
Stereo 3.8W Output, RL = 4Ω
DC-controlled Volume Control
Short Circuit Protection
APPLICATIONS
•
•
•
Flat Panel Monitors
Flat Panel TV's
Computer Sound Cards
KEY SPECIFICATIONS
•
•
•
Quiscent Power Supply Current 18mA (typ)
POUT @
VDD = 12V, RL = 4Ω, 10% THD+N 3.8W (typ)
Shutdown current 55μA (typ)
Eliminating external feedback resistors, an internal,
DC-controlled, volume control allows easy and
variable gain adjustment.
Boomer audio power amplifiers were designed
specifically to provide high quality output power with a
minimal amount of external components. The
LM4952 does not require bootstrap capacitors or
snubber circuits. Therefore, it is ideally suited for
display applications requiring high power and minimal
size.
The LM4952 features a low-power consumption
active-low shutdown mode. Additionally, the LM4952
features an internal thermal shutdown protection
mechanism along with short circuit protection.
The LM4952 contains advanced pop & click circuitry
that eliminates noises which would otherwise occur
during turn-on and turn-off transitions.
1
2
3
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.
Boomer is a trademark of Texas Instruments Incorporated.
All other 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 © 2004–2013, Texas Instruments Incorporated
LM4952
SNAS230A – AUGUST 2004 – REVISED MAY 2013
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Connection Diagram
BYPASS
UZXYTT
L4952TS
-VIN
B
VOUT
B
VDD
GND
VOUT
A
SHUTDOWN
-VIN
A
DC VOL
Figure 1. DDPAK – Top View
See Package Number KTW
L4952TS = LM4952TS
Typical Application
VDD
CS
10 PF
6
CIN A
0.39 PF
AUDIO
INPUT A
2 -VIN A
COUTA
VOLUME
AMPA
+
SHUTDOWN
CONTROL
3
SHUTDOWN
9
BYPASS
C BYPAS
VOUTA
DCCONTROLLED
VOLUME
CONTROL
BIAS
4.7 PF
DC-VOL 1
8
-VIN B
AMPB
VOLUME
0V - 3.3V
COUTB
+
CIN B
0.39 PF
RL
4:
S
AUDIO
INPUT B
470 PF
4
VOUTB 7
470 PF
-
RL
4:
5
Figure 2. Typical LM4952 SE Audio Amplifier Application Circuit
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.
2
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Absolute Maximum Ratings (1) (2) (3)
Supply Voltage (pin 6, referenced to GND, pins 4 and 5)
18.0V
−65°C to +150°C
Storage Temperature
−0.3V to VDD + 0.3V
pins 4, 6, and 7
Input Voltage
−0.3V to 9.5V
pins 1, 2, 3, 8, and 9
(4)
Internally limited
ESD Susceptibility (5)
2000V
ESD Susceptibility (6)
200V
Power Dissipation
Junction Temperature
150°C
θJC (TS)
θJA (TS) (4)
Thermal Resistance
(1)
(2)
(3)
(4)
(5)
(6)
4°C/W
20°C/W
All voltages are measured with respect to the GND 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 specify specific performance limits. Electrical Characteristics state DC and AC electrical
specifications under particular test conditions which specify specific performance limits. This assumes that the device is within the
Operating Ratings. Specifications are not specified for parameters where no limit is given, however, the typical value is a good indication
of device performance.
If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and
specifications.
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 given in Absolute Maximum Ratings, whichever is
lower. For the LM4952 typical application (shown in Figure 2) with VDD = 12V, RL = 4Ω stereo operation the total power dissipation is
3.65W. θJA = 20°C/W for the DDPAK package mounted to 16in2 heatsink surface area.
Human body model, 100pF discharged through a 1.5kΩ resistor.
Machine Model, 220pF–240pF discharged through all pins.
Operating Ratings
TMIN ≤ TA ≤ TMAX
Temperature Range
−40°C ≤ T A ≤ 85°C
9.6V ≤ VDD ≤ 16V
Supply Voltage
Electrical Characteristics VDD = 12V (1) (2)
The following specifications apply for VDD = 12V, AV = 20dB (nominal), RL = 4Ω, and TA = 25°C unless otherwise noted.
Symbol
IDD
Parameter
Quiescent Power Supply Current
Conditions
VIN = 0V, IO = 0A, No Load
(6)
LM4952
Units
(Limits)
Typical (3)
Limit (4) (5)
18
35
mA (max)
55
85
µA (max)
ISD
Shutdown Current
VSHUTDOWN = GND
RIN
Amplifier Input Resistance
VDC VOL = VDD/2
44
VDC VOL = GND
200
kΩ
kΩ
VIN
Amplifier Input Signal
VDD/2
Vp-p (max)
VSDIH
Shutdown Voltage Input High
2.0
VDD/2
V (min)
V (max)
VSDIL
Shutdown Voltage Input Low
0.4
V (max)
TWU
Wake-up Time
TSD
Thermal Shutdown Temperature
PO
Output Power
(1)
(2)
(3)
(4)
(5)
(6)
CB = 4.7µF
f = 1kHz,
THD+N = 1%
THD+N = 10%
440
ms
170
°C
3.1
3.8
2.8
W (min)
All voltages are measured with respect to the GND 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 specify specific performance limits. Electrical Characteristics state DC and AC electrical
specifications under particular test conditions which specify specific performance limits. This assumes that the device is within the
Operating Ratings. Specifications are not specified 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 ensured to AOQL (Average Outgoing Quality Level).
Datasheet min/max specification limits are ensured by design, test, or statistical analysis.
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.
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Electrical Characteristics VDD = 12V(1)(2) (continued)
The following specifications apply for VDD = 12V, AV = 20dB (nominal), RL = 4Ω, and TA = 25°C unless otherwise noted.
Symbol
Parameter
Conditions
LM4952
Typical
THD+N
Total Harmomic Distortion + Noise
PO = 2.0Wrms, f = 1kHz
εOS
Output Noise
A-Weighted Filter, VIN = 0V,
Input Referred
XTALK
Channel Separation
fIN = 1kHz, PO = 1W,
Input Referred
RL = 8Ω
RL = 4Ω
(3)
Limit
(4) (5)
Units
(Limits)
0.08
%
8
µV
78
72
dB
PSRR
Power Supply Rejection Ratio
VRIPPLE = 200mVp-p, f = 1kHz,
Input Referred
89
IOL
Output Current Limit
VIN = 0V, RL = 500mΩ
5
80
dB (min)
A
Electrical Characteristics for Volume Control (1) (2)
The following specifications apply for VDD = 12V, AV = 20dB (nominal), and TA = 25°C unless otherwise noted.
Symbol
Parameter
LM4952
Conditions
Typical (3)
VOLmax
Gain
VDC-VOL = Full scale, No Load
20
VOLmin
Gain
VDC-VOL = +1LSB, No Load
-46
AM
Mute Attenuation
VDC-VOL = 0V, No Load
75
(1)
(2)
(3)
(4)
Limit (4)
Units
(Limits)
dB
dB
63
dB (min)
All voltages are measured with respect to the GND 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 specify specific performance limits. Electrical Characteristics state DC and AC electrical
specifications under particular test conditions which specify specific performance limits. This assumes that the device is within the
Operating Ratings. Specifications are not specified 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 ensured to AOQL (Average Outgoing Quality Level).
External Components Description
Refer to Figure 2.
Components
Functional Description
1. 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 SELECTING EXTERNAL COMPONENTS,
for an explanation of determining CIN's value.
2. CS
The supply bypass capacitor. Refer to POWER SUPPLY BYPASSING for information about properly placing, and
selecting the value of, this capacitor.
3. CBYPASS
This capacitor filters the half-supply voltage present on the BYPASS pin. Refer to SELECTING EXTERNAL
COMPONENTS for information about properly placing, and selecting the value of, this capacitor.
4
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Typical Performance Characteristics
AV = 20dB and TA = 25°C, unless otherwise noted.
THD+N vs Frequency
THD+N vs Frequency
10
10
5
5
2
2
1
THD+N (%)
THD+N (%)
1
0.5
0.2
0.5
0.2
0.1
0.1
0.05
0.05
0.02
0.02
0.01
20
50 100 200 500 1k 2k
0.01
20
5k 10k 20k
FREQUENCY (Hz)
VDD = 12V, RL = 4Ω,
POUT = 2W, CIN = 1.0µF
10
VDD = 12V, RL = 8Ω,
POUT = 1W, CIN = 1.0µF
Figure 3.
THD+N vs Output Power
10
5
5
2
2
Figure 4.
THD+N vs Output Power
1
THD+N (%)
THD+N (%)
5k 10k 20k
FREQUENCY (Hz)
1
0.5
0.2
0.5
0.2
0.1
0.1
0.05
0.05
0.02
0.02
0.01
10m 20m 50m 100m 200m 500m 1
2
0.01
10m 20m 50m 100m 200m 500m 1
56
OUTPUT POWER (W)
VDD = 12V, RL = 4Ω,
fIN = 1kHz
50 100 200 500 1k 2k
VDD = 12V, RL = 8Ω,
fIN = 1kHz
Figure 5.
Output Power vs Power Supply Voltage
RL = 4Ω, fIN = 1kHz
both channels driven and loaded (average shown),
at (from top to bottom at 12V):
THD+N = 10%, THD+N = 1%
Figure 7.
2
56
OUTPUT POWER (W)
Figure 6.
Output Power vs Power Supply Voltage
RL = 8Ω, fIN = 1kHz
both channels driven and loaded (average shown),
at (from top to bottom at 12V):
THD+N = 10%, THD+N = 1%
Figure 8.
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Typical Performance Characteristics (continued)
AV = 20dB and TA = 25°C, unless otherwise noted.
MAGNITUDE (dB)
Power Supply Rejection vs Frequency
Total Power Dissipation vs Load Dissipation
+0
-5
-10
-15
-20
-25
-30
-35
-40
-45
-50
-55
-60
-65
-70
-75
-80
-85
-90
-95
-100
20
50 100 200 500 1k 2k
5k 10k 20k
FREQUENCY (Hz)
VDD = 12V, RL = 4Ω,
VRIPPLE = 200mVp-p
VDD = 12V, fIN = 1kHz,
at (from top to bottom at 1W):
RL = 4Ω, RL = 8Ω
Figure 9.
Output Power vs Load Resistance
Figure 10.
Channel-to-Channel Crosstalk vs Frequency
+0
-10
-20
AMPLITUDE (dB)
-30
-40
-50
-60
-70
-80
-90
-100
-110
-120
20
50 100 200 500 1k 2k
5k 10k 20k
FREQUENCY (Hz)
VDD = 12V, RL = 4Ω, POUT = 1W, Input Referred
at (from top to bottom at 1kHz): VINB driven,
VOUTA measured, VINA driven, VOUTB measured
VDD = 12V, fIN = 1kHz,
at (from top to bottom at 15Ω):
THD+N = 10%, THD+N = 1%
Figure 11.
Figure 12.
Channel-to-Channel Crosstalk vs Frequency
Amplifier Gain vs DC Volume Voltage
+0
20
-10
10
-20
0
AMPLIFIER GAIN (dB)
AMPLITUDE (dB)
-30
-40
-50
-60
-70
-80
-90
-20
-30
-40
-50
-100
-60
-110
-70
-120
20
50 100 200 500 1k 2k
-80
-0 +0.5 +1 +1.5 +2 +2.5 +3 +3.5 +4 +4.5 +5
5k 10k 20k
FREQUENCY (Hz)
VDD = 12V, RL = 8Ω, POUT = 1W, Input Referred
at (from top to bottom at 1kHz): VINB driven,
VOUTA measured, VINA driven, VOUTB measured
Figure 13.
6
-10
DC VOLUME VOLTAGE (V)
VDD = 12V, RL = 8Ω, at (from top to bottom at 1.5V):
Decreasing DC Volume Voltage, Increasing DC Volume Voltage
Figure 14.
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Typical Performance Characteristics (continued)
AV = 20dB and TA = 25°C, unless otherwise noted.
THD+N vs Frequency
20
10
10
5
0
2
-10
1
THD+N (%)
AMPLIFIER GAIN (dB)
Amplifier Gain vs Part-to-Part DC Volume Voltage
Variation (Five parts)
-20
-30
-40
0.5
0.2
0.1
-50
0.05
-60
-70
0.02
-80
-0 +0.5 +1 +1.5 +2 +2.5 +3 +3.5 +4 +4.5 +5
0.01
20
50 100 200 500 1k 2k
VDD = 9.6V, RL = 4Ω,
POUT = 1.1W, CIN = 1.0µF
VDD = 12V, RL = 8Ω,
Figure 15.
Figure 16.
THD+N vs Frequency
10
10
5
5
2
2
THD+N (%)
0.5
0.2
0.5
0.2
0.1
0.1
0.05
0.05
0.02
0.02
0.01
20
THD+N vs Output Power
1
1
THD+N (%)
5k 10k 20k
FREQUENCY (Hz)
DC VOLUME VOLTAGE (V)
50 100 200 500 1k 2k
0.01
10m 20m 50m 100m 200m 500m 1
5k 10k 20k
FREQUENCY (Hz)
56
OUTPUT POWER (W)
VDD = 9.6V, RL = 8Ω,
POUT = 850mW, CIN = 1.0µF
VDD = 9.6V, RL = 4Ω,
fIN = 1kHz
Figure 17.
10
2
THD+N vs Output Power
Figure 18.
Total Power Dissipation vs Load Dissipation
5
2
THD+N (%)
1
0.5
0.2
0.1
0.05
0.02
0.01
10m 20m 50m 100m 200m 500m 1
2
56
OUTPUT POWER (W)
VDD = 9.6V, RL = 8Ω,
fIN = 1kHz
Figure 19.
VDD = 9.6V, fIN = 1kHz
at (from top to bottom at 1W):
RL = 4Ω, RL = 8Ω
Figure 20.
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Typical Performance Characteristics (continued)
AV = 20dB and TA = 25°C, unless otherwise noted.
Power Supply Rejection vs Frequency
MAGNITUDE (dB)
Output Power vs Load Resistance
+0
-5
-10
-15
-20
-25
-30
-35
-40
-45
-50
-55
-60
-65
-70
-75
-80
-85
-90
-95
-100
20
50 100 200 500 1k 2k
5k 10k 20k
FREQUENCY (Hz)
VDD = 9.6V, RL = 4Ω,
VRIPPLE = 200mVP-P
VDD = 9.6V, fIN = 1kHz,
at (from top to bottom at 15Ω):
THD+N = 10%, THD+N = 1%
Figure 22.
Channel-to Channel Crosstalk vs Frequency
Channel-to Channel Crosstalk vs Frequency
+0
+0
-10
-10
-20
-20
-30
-30
AMPLITUDE (dB)
AMPLITUDE (dB)
Figure 21.
-40
-50
-60
-70
-80
-40
-50
-60
-70
-80
-90
-90
-100
-100
-110
-110
-120
-120
20
50 100 200 500 1k 2k
20
5k 10k 20k
VDD = 9.6V, RL = 4Ω, POUT = 1W, Input Referred
at (from top to bottom at 1kHz): VINB driven, VOUTA measured; VINA
driven, VOUTB measured
Figure 23.
THD+N vs Frequency
THD+N vs Frequency
10
5
5
2
2
1
THD+N (%)
THD+N (%)
1
0.5
0.2
0.5
0.2
0.1
0.1
0.05
0.05
0.02
0.02
50 100 200 500 1k 2k
0.01
20
5k 10k 20k
FREQUENCY (Hz)
VDD = 14V, RL = 4Ω,
POUT = 2W, CIN = 1.0µF
8
5k 10k 20k
VDD = 9.6V, RL = 8Ω, POUT = 1W, Input Referred
at (from top to bottom at 1kHz): VINB driven, VOUTA measured; VINA
driven, VOUTB measured
Figure 24.
10
0.01
20
50 100 200 500 1k 2k
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 25.
50 100 200 500 1k 2k
5k 10k 20k
FREQUENCY (Hz)
VDD = 14V, RL = 8Ω,
POUT = 1W, CIN = 1.0µF
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Typical Performance Characteristics (continued)
AV = 20dB and TA = 25°C, unless otherwise noted.
10
THD+N vs Output Power
10
5
5
2
2
1
THD+N (%)
THD+N (%)
1
THD+N vs Output Power
0.5
0.2
0.5
0.2
0.1
0.1
0.05
0.05
0.02
0.02
0.01
10m 20m 50m 100m 200m 500m 1
2
0.01
10m 20m 50m 100m 200m 500m 1
56
OUTPUT POWER (W)
VDD = 14V, RL = 4Ω,
fIN = 1kHz
VDD = 14V, RL = 8Ω
fIN = 1kHz
Figure 27.
Power Supply Rejection vs Frequency
POWER SUPPLY REJECTION (dB)
2
56
OUTPUT POWER (W)
Figure 28.
Output Power vs Load Resistance
+0
-5
-10
-15
-20
-25
-30
-35
-40
-45
-50
-55
-60
-65
-70
-75
-80
-85
-90
-95
-100
20
50 100 200 500 1k 2k
5k 10k 20k
FREQUENCY (Hz)
VDD = 14V, RL = 4Ω
VRIPPLE = 200mVP-P
Figure 29.
VDD = 15V, fIN = 1kHz,
at (from top to bottom at 2W):
RL = 4Ω, RL = 8Ω
THD+N vs Output Power
VDD = 15V, at (from top to bottom at 15Ω):
THD+N = 10%, THD+N = 1%, fIN = 1kHz
Figure 31.
Figure 30.
THD+N vs Output Power
VDD = 16V, RL = 4Ω,
fIN = 1kHz
Figure 32.
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Typical Performance Characteristics (continued)
AV = 20dB and TA = 25°C, unless otherwise noted.
Channel-to-Channel Crosstalk vs Frequency
+0
+0
-10
-10
-20
-20
-30
-30
AMPLITUDE (dB)
AMPLITUDE (dB)
Channel-to-Channel Crosstalk vs Frequency
-40
-50
-60
-70
-80
-40
-50
-60
-70
-80
-90
-90
-100
-100
-110
-110
-120
20
50 100 200 500 1k 2k
-120
20
5k 10k 20k
50 100 200 500 1k 2k
FREQUENCY (Hz)
VDD = 16V, RL = 4Ω, POUT = 1W, Input Referred
at (from top to bottom at 1kHz): VINB driven, VOUTA measured; VINA
driven, VOUTB measured
Figure 33.
VDD = 16V, RL = 8Ω, POUT = 1W, Input Referred
at (from top to bottom at 1kHz): VINB driven, VOUTA measured; VINA
driven, VOUTB measured
Figure 34.
Power Supply Current vs Power Supply Voltage
Clipping Voltage vs Power Supply Voltage
1.75
1.5
25
CLIPPING VOLTAGE (V)
POWER SUPPLY CURRENT (mA)
30
20
15
10
1.25
1
0.75
0.5
0.25
0
9.5
5
9
10
11
12
13
14
15
16
17
10.5
11.5
12.5
13.5
14.5
15.5
POWER SUPPLY VOLTAGE (V)
POWER SUPPLY VOLTAGE (V)
RL = 4Ω, fIN = 1kHz
at (from top to bottom at 12.5V):
positive signal swing, negative signal swing
Figure 36.
RL = 4Ω,
VIN = 0V, RSOURCE = 50Ω
Figure 35.
Clipping Voltage vs Power Supply Voltage
Power Dissipation vs Ambient Temperature
1.25
CLIPPING VOLTAGE (V)
5k 10k 20k
FREQUENCY (Hz)
1
0.75
0.5
0.25
0
9.5
10.5
11.5
12.5
13.5
14.5
15.5
POWER SUPPLY VOLTAGE (V)
RL = 8Ω, fIN = 1kHz
at (from to bottom at 12.5V):
positive signal swing, negative signal swing
Figure 37.
10
VDD = 12V, RL = 4Ω (SE), fIN = 1kHz,
(from to bottom at 80°C): 16in2 copper plane heatsink area, 8in2
copper plane heatsink area
Figure 38.
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Typical Performance Characteristics (continued)
AV = 20dB and TA = 25°C, unless otherwise noted.
Power Dissipation vs Ambient Temperature
VDD = 12V, RL = 8Ω, fIN = 1kHz,
(from to bottom at 120°C): 16in2 copper plane heatsink area, 8in2 copper plane heatsink area
Figure 39.
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LM4952
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APPLICATION INFORMATION
HIGH VOLTAGE BOOMER WITH INCREASED OUTPUT POWER
VDD
CS
10 PF
6
CIN A
0.39 PF
AUDIO
INPUT A
2 -VIN A
COUTA
VOLUME
AMPA
+
SHUTDOWN
CONTROL
3
SHUTDOWN
9
BYPASS
C BYPAS
VOUTA
DCCONTROLLED
VOLUME
CONTROL
BIAS
4.7 PF
DC-VOL 1
8
-VIN B
AMPB
VOLUME
0V - 3.3V
COUTB
+
CIN B
0.39 PF
RL
4:
S
AUDIO
INPUT B
470 PF
4
VOUTB 7
470 PF
-
RL
4:
5
Figure 40. Typical LM4952 SE Application Circuit
Unlike previous 5V Boomer amplifiers, the LM4952 is designed to operate over a power supply voltages range of
9.6V to 16V. Operating on a 12V power supply, the LM4952 will deliver 3.8W into a 4Ω SE load with no more
than 10% THD+N.
POWER DISSIPATION
Power dissipation is a major concern when designing a successful single-ended or bridged amplifier. Equation 1
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
(1)
The LM4952's dissipation is twice the value given by Equation 1 when driving two SE loads. For a 12V supply
and two 4Ω SE loads, the LM4952's dissipation is 1.82W.
The maximum power dissipation point given by Equation 1 must not exceed the power dissipation given by
Equation 2:
PDMAX' = (TJMAX - TA) / θJA
(2)
The LM4952's TJMAX = 150°C. In the TS package, the LM4952'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.
Connect the two layers together under the tab with a 5x5 array of vias. At any given ambient temperature TA, use
Equation 2 to find the maximum internal power dissipation supported by the IC packaging. Rearranging
Equation 2 and substituting PDMAX for PDMAX' results in Equation 3. This equation gives the maximum ambient
temperature that still allows maximum stereo power dissipation without violating the LM4952's maximum junction
temperature.
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TA = TJMAX - PDMAX-SEθJA
(3)
For a typical application with a 12V power supply and an SE 4Ω load, the maximum ambient temperature that
allows maximum stereo power dissipation without exceeding the maximum junction temperature is approximately
77°C for the TS package.
TJMAX = PDMAX-MONOBTLθJA + TA
(4)
Equation 4 gives the maximum junction temperature TJMAX. If the result violates the LM4952'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.
If the result of Equation 1 is greater than that of Equation 2, 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.
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 Absolute Maximum Ratings (1) (2) (3).
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 10µF tantalum bypass capacitance
connected between the LM4952'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 LM4952's power supply pin and ground as short as possible.
BYPASS PIN BYPASSING
Connecting a 4.7µF 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. The selection of bypass capacitor values,
especially CBYPASS, depends on desired PSRR requirements, click and pop performance (as explained in
SELECTING EXTERNAL COMPONENTS), system cost, and size constraints.
MICRO-POWER SHUTDOWN
The LM4952 features an active-low micro-power shutdown mode. When active, the LM4952's micro-power
shutdown feature turns off the amplifier's bias circuitry, reducing the supply current. The low 55µA 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.
(1)
(2)
(3)
All voltages are measured with respect to the GND 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 specify specific performance limits. Electrical Characteristics state DC and AC electrical
specifications under particular test conditions which specify specific performance limits. This assumes that the device is within the
Operating Ratings. Specifications are not specified for parameters where no limit is given, however, the typical value is a good indication
of device performance.
If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and
specifications.
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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. Figure 41 shows a simple switch-based circuit that can be
used to control the LM4952's shutdown fucntion. Select normal amplifier operation by closing the switch.
Opening the switch applies GND to the SHUTDOWN pin, activating micro-power shutdown. The switch and
resistor ensure 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.
VDD
SPST
47 k:
To SHUTDOWN Pin
47 k:
Figure 41. Simple switch and voltage divider generates shutdown control signal
DC VOLUME CONTROL
The LM4952 has an internal stereo volume control whose setting is a function of the DC voltage applied to the
DC VOL input pin.
The LM4952 volume control consists of 31 steps that are individually selected by a variable DC voltage level on
the volume control pin. As shown in Figure 42, the range of the steps, controlled by the DC voltage, is 20dB to 46dB.
The gain levels are 1dB/step from 20dB to 14dB, 2dB/step from 14dB to -16dB, 3dB/step from -16dB to -27dB,
4dB/step from -27db to -31dB, 5dB/step from -31dB to -46dB.
20
10
AMPLIFIER GAIN (dB)
0
-10
-20
-30
-40
-50
-60
-70
-80
-0 +0.5 +1 +1.5 +2 +2.5 +3 +3.5 +4 +4.5 +5
DC VOLUME VOLTAGE (V)
Figure 42. Volume Control Response
Like all volume controls, the LM4952's internal volume control is set while listening to an amplified signal that is
applied to an external speaker. The actual voltage applied to the DC VOL input pin is a result of the volume a
listener desires. As such, the volume control is designed for use in a feedback system that includes human ears
and preferences. This feedback system operates quite well without the need for accurate gain. The user simply
sets the volume to the desired level as determined by their ear, without regard to the actual DC voltage that
14
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produces the volume. Therefore, the accuracy of the volume control is not critical, as long as volume changes
monotonically and step size is small enough to reach a desired volume that is not too loud or too soft. Since the
gain is not critical, there may be a volume variation from part-to-part even with the same applied DC volume
control voltage. The gain of a given LM4952 can be set with fixed external voltage, but another LM4952 may
require a different control voltage to achieve the same gain. Figure 43 is a curve showing the volume variation of
five typical LM4952s as the voltage applied to the DC VOL input pin is varied. For gains between –20dB and
+16dB, the typical part-to-part variation is typically ±1dB for a given control voltage.
20
10
AMPLIFIER GAIN (dB)
0
-10
-20
-30
-40
-50
-60
-70
-80
-0 +0.5 +1 +1.5 +2 +2.5 +3 +3.5 +4 +4.5 +5
DC VOLUME VOLTAGE (V)
Figure 43. Typical Part-to-Part Gain Variation as a Function of DC Vol Control Voltage
VOLUME CONTROL VOLTAGE GENERATION
Figure 44 shows a simple circuit that can be used to create an adjustable DC control voltage that is applied to
the DC Vol input. The 91kΩ series resistor and the 50kΩ potentiometer create a voltage divider between the
supply voltage, VDD, and GND. The series resistor’s value assumes a 12V power supply voltage. The voltage
present at the node between the series resistor and the top of the potentiometer need only be a nominal value of
3.5V and must not exceed 9.5V, as stated in the LM4952’s Absolute Maximum Ratings.
VDD
91 k:
RS
50 k:
RVOL
4
DC VOL
LM4952
10 PF*
* optional
Capacitor connected to DC VOL pin minimizes voltage fluctuation when using unregulated supplies that could cause
changes in perceived volume setting.
Figure 44. Typical Circuit Used for DC Voltage Volume Control
UNREGULATED POWER SUPPLIES AND THE DC VOL CONTROL
As an amplifier’s output power increases, the current that flows from the power supply also increases. If an
unregulated power supply is used, its output voltage can decrease (“droop” or “sag”) as this current increases. It
is not uncommon for an unloaded unregulated 15V power supply connected to the LM4952 to sag by as much as
2V when the amplifier is drawing 1A to 2A while driving 4Ω stereo loads to full power dissipation. Figure 45 is an
oscilloscope photo showing an unregulated power supply’s voltage sag while powering an LM4952 that is driving
4Ω stereo loads. The amplifier’s input is a typical music signal supplied by a CD player. As shown, the sag can
be quite significant.
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Wave forms shown include VDD (Trace A), VOUT A (Trace B), VOUT B (Trace C), and the DC voltage applied to the DC
VOL pin (Trace D).
Figure 45. LM4952 Operating on an Unregulated 12V (Nominal) Power Supply
This sagging supply voltage presents a potential problem when the voltage that drives the DC Vol pin is derived
from the voltage supplied by an unregulated power supply. This is the case for the typical volume control circuit
(a 50kΩ potentiometer in series with a 91kΩ resistor) shown in Figure 44. The potentiometer’s wiper is
connected to the DC Vol pin. With this circuit, power supply voltage fluctuations will be seen by the DC Vol input.
Though attenuated by the voltage divider action of the potentiometer and the series resistor, these fluctuations
may cause perturbations in the perceived volume. An easy and simple solution that suppresses these
perturbations is a 10μF capacitor connected between the DC Vol pin and ground. See the result of this capacitor
in Figure 46. This capacitance can also be supplemented with bulk capacitance in the range of 1000μF to
10,000μF connected to the unregulated power supply’s output. Figure 48 shows how this bulk capacitance
minimizes fluctuations on VDD.
Same conditions and waveforms as shown in Figure 45, except that a 10μF capacitor has been connected between
the DC VOL pin and GND (Trace D).
Figure 46.
If space constraints preclude the use of a 10μF capacitor connected to the DC Vol pin or large amounts of bulk
supply capacitance, or if more resistance to the fluctuations is desired, using an LM4040-4.1 voltage reference
shown in Figure 47 is recommended. The value of the 91kΩ resistor, already present in the typical volume
applications circuit, should be changed to 62kΩ. This sets the LM4040-4.1’s bias current at 125μA when using a
nominal 12V supply, well within the range of current needed by this reference.
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VDD
62 k:
50 k:
4
DC VOL
LM4040-4.1
RVOL
LM4952
Using an LM4040–4.1 to set the maximum DC volume control voltage and attenuate power supply variations when
using unregulated supplies that would otherwise perturb the volume setting.
Figure 47.
Same conditions and waveforms as shown in Figure 46, except that a 4700μF capacitor has been connected
between the VDD pin and GND (Trace A).
Figure 48.
SELECTING EXTERNAL COMPONENTS
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.
The amplifier's input resistance and the input capacitor (CIN) produce a high pass filter cutoff frequency that is
found using Equation 5.
FCIN = 1/(2πRINCIN)
(5)
As an example when using a speaker with a low frequency limit of 50Hz and based on the LM4952's 44kΩ
nominal minimum input resistance, CIN, using Equation 5 is 0.072μF. The 0.39μF CINA shown in Figure 40 allows
the LM4952 to drive high efficiency, full range speaker whose response extends below 30Hz.
Similarly, the output coupling capacitor and the load impedance also form a high pass filter. The cutoff frequency
formed by these two components is found using Equation 6.
fCOUT = 1/(2πRLOADCOUT)
(6)
Expanding on the example above and assuming a nominal speaker impedance of 4Ω, response below 30Hz is
assured if the output coupling capacitors have a value, using Equation 6, greater than 1330μF.
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 LM4952 settles to quiescent
operation, its value is critical when minimizing turn-on pops. The slower the LM4952’s outputs ramp to their
quiescent DC voltage (nominally VDD/2), the smaller the turn-on pop. Choosing CBYPASS equal to 4.7μF 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.
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Routing Input and BYPASS Capacitor Grounds
Optimizing the LM4952’s low distortion performance is easily accomplished by connecting the input signal’s
ground reference directly to the DDPAK’s grounded tab connection. In like manner, the ground lead of the
capacitor connected between the BYPASS pin and GND should also be connected to the package’s grounded
tab.
OPTIMIZING CLICK AND POP REDUCTION PERFORMANCE
The LM4952 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/4 voltage present at the BYPASS pin ramps to its final value, the LM4952's internal amplifiers are
muted. Once the voltage at the BYPASS pin reaches VDD/4, the amplifiers are unmuted.
The gain of the internal amplifiers remains unity until the voltage on the bypass pin reaches VDD/4. 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.
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 selecting a CBYPASS value that
is greater than twelve times CIN's value.
RECOMMENDED PRINTED CIRCUIT BOARD LAYOUT
Figure 47 through Figure 49 show the recommended two-layer PC board layout that is optimized for the DDPAKpackaged, SE-configured LM4952 and associated external components. These circuits are designed for use with
an external 12V supply and 4Ω(min)(SE) speakers.
These circuit boards are 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 respective GND pins.
Demonstration Board Layout
Figure 49. Recommended TS SE PCB Layout:
Top Silkscreen
18
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Figure 50. Recommended TS SE PCB Layout:
Top Layer
Figure 51. Recommended TS SE PCB Layout:
Bottom Layer
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LM4952
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REVISION HISTORY
Changes from Original (May 2013) to Revision A
•
20
Page
Changed layout of National Data Sheet to TI format .......................................................................................................... 19
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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)
LM4952TS/NOPB
ACTIVE
DDPAK/
TO-263
KTW
9
45
RoHS-Exempt
& Green
SN
Level-3-245C-168 HR
-40 to 85
LM4952TS
LM4952TSX/NOPB
ACTIVE
DDPAK/
TO-263
KTW
9
500
RoHS-Exempt
& Green
SN
Level-3-245C-168 HR
-40 to 85
LM4952TS
(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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