LM4951A [TI]
具有短路保护的 1.8W 单声道 2.7V 至 9V 模拟输入 AB 类音频放大器;
| 型号： | LM4951A |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | 具有短路保护的 1.8W 单声道 2.7V 至 9V 模拟输入 AB 类音频放大器 放大器 音频放大器 |
| 文件： | 总25页 (文件大小：1539K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LM4951A
www.ti.com
SNAS453C –AUGUST 2008–REVISED APRIL 2013
LM4951A
Wide Voltage Range 1.8 Watt Audio Amplifier
With Short Circuit Protection
Check for Samples: LM4951A
1
FEATURES
DESCRIPTION
The LM4951A is an audio power amplifier designed
for applications with supply voltages ranging from
2.7V up to 9V. The LM4951A is capable of delivering
1.8W continuous average power with less than 1%
THD+N into a bridge connected 8Ω load when
operating from a 7.5VDC power supply.
23
•
Pop & Click Circuitry Eliminates Noise During
Turn-On and Turn-Off Transitions
•
Wide Supply Voltage Range: 2.7V to 9V
Low Current, Active-Low Shutdown Mode
Low Quiescent Current
•
•
•
•
•
•
Boomer™ audio power amplifiers were designed
specifically to provide high quality output power with a
minimal amount of external components. The
LM4951A does not require bootstrap capacitors, or
snubber circuits.
Thermal Shutdown Protection
Short Circuit Protection
Unity-Gain Stable
External Gain Configuration Capability
The LM4951A features a low-power consumption
active-low shutdown mode. Additionally, the
LM4951A features an internal thermal shutdown
protection mechanism and short circuit protection.
APPLICATIONS
•
•
•
•
•
Portable Devices
Cell Phones
The LM4951A contains advanced pop & click circuitry
that eliminates noises which would otherwise occur
during turn-on and turn-off transitions.
Laptop Computers
Computer Speaker Systems
MP3 Player Speakers
The LM4951A 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
1.8 W (typ)
•
•
Shutdown Current 0.01µA (typ)
Fast Turn on Time 25ms (typ)
1
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.
2
3
Boomer is a trademark of Texas Instruments.
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 © 2008–2013, Texas Instruments Incorporated
LM4951A
SNAS453C –AUGUST 2008–REVISED APRIL 2013
www.ti.com
Typical Application
Rf
V
DD
C
s
1.0 mF
V
DD
R
i
C
i
20k
V
IN
0.39 mF
-
V -
o
AMP
A
+
C
CHG
1k
R
c
20k
Control
Bias
C
BYPASS
Bypass
1.0 mF
V
IH
8W
V
IL
Shutdown
control
20k
Shutdown
+
AMP
B
V +
o
-
GND
Figure 1. Typical Bridge-Tied-Load (BTL) Audio Amplifier Application Circuit
Connection Diagram
Top View
+
Bypass
1
2
3
4
5
10
9
V
V
O
Shutdown
DD
8
NC
C
CHG
NC
7
GND
-
6
V
V
O
IN
Figure 2. WSON Package
See Package Number DPR0010A
Pin Name and Function
Pin Number
Name
Function
Type
½ supply reference voltage bypass output. See sections POWER SUPPLY
BYPASSING and SELECTING EXTERNAL COMPONENTS for more
information.
1
Bypass
Analog Output
Digital Input
Shutdown control active low signal. A logic low voltage will put the
LM4951A into Shutdown mode.
2
Shutdown
2
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM4951A
LM4951A
www.ti.com
SNAS453C –AUGUST 2008–REVISED APRIL 2013
Pin Name and Function (continued)
Pin Number
Name
Function
Type
Input capacitor charge to decrease turn on time. See section Selecting
Value A For RCfor more information.
3
CCHG
Analog Output
4
5
NC
VIN
No connection to die. Pin can be connected to any potential.
Single-ended signal input pin.
No Connect
Analog Input
Analog Output
Ground
6
VO-
GND
NC
Inverting output of amplifier.
7
Ground connection.
8
No connection to die. Pin can be connected to any potential.
Power supply.
No Connect
Power
9
VDD
VO+
10
Non-Inverting output of amplifier.
Analog Output
No connect. Pin must be electrically isolated (floating) or connected to
GND.
Exposed DAP
NC
No Connect
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)
Supply Voltage
9.5V
Storage Temperature
−65°C to +150°C
Input Voltage
−0.3V to VDD + 0.3V
Power Dissipation(3)
ESD Rating(4)
Internally limited
2000V
ESD Rating(5)
200V
Junction Temperature (TJMAX
Thermal Resistance
Soldering Information
)
150°C
73°C/W
θJA (WSON)(3)
AN-1187 (Literature Number SNOA401)
(1) “Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur, including inoperability and degradation of
device reliability and/or performance. Functional operation of the device and/or non-degradation at the s or other conditions beyond
those indicated in the Recommended Operating Conditions is not implied. The Recommended Operating Conditionsindicate conditions
at which the device is functional and the device should not be operated beyond such conditions. All voltages are measured with respect
to the ground pin, unless otherwise specified.
(2) The Electrical Characteristics tables list ensured specifications under the listed Recommended Operating Conditions except as
otherwise modified or specified by the Electrical Characteristics Conditions and/or Notes. Typical specifications are estimations only and
are not ensured.
(3) The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, θJA, and the ambient temperature,
TA. The maximum allowable power dissipation is PDMAX = (TJMAX - TA) / θJA or the number given in Absolute Maximum Ratings,
whichever is lower. For the LM4951A typical application (shown in Figure 1) with VDD = 7.5V, RL = 8Ω mono-BTL operation the max
power dissipation is 1.42W. θJA = 73ºC/W.
(4) Human body model, applicable std. JESD22-A114C.
(5) Machine model, applicable std. JESD22-A115-A.
Operating Ratings(1)(2)
Temperature Range TMIN ≤ TA ≤ TMAX
−40°C ≤ T A ≤ +85°C
2.7V ≤ VDD ≤ 9V
Supply Voltage
(1) “Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur, including inoperability and degradation of
device reliability and/or performance. Functional operation of the device and/or non-degradation at the s or other conditions beyond
those indicated in the Recommended Operating Conditions is not implied. The Recommended Operating Conditionsindicate conditions
at which the device is functional and the device should not be operated beyond such conditions. All voltages are measured with respect
to the ground pin, unless otherwise specified.
(2) The Electrical Characteristics tables list ensured specifications under the listed Recommended Operating Conditions except as
otherwise modified or specified by the Electrical Characteristics Conditions and/or Notes. Typical specifications are estimations only and
are not ensured.
Copyright © 2008–2013, Texas Instruments Incorporated
Submit Documentation Feedback
3
Product Folder Links: LM4951A
LM4951A
SNAS453C –AUGUST 2008–REVISED APRIL 2013
www.ti.com
Electrical Characteristics VDD = 7.5V(1)(2)
The following specifications apply for VDD = 7.5V, AV-BTL = 6dB, RL = 8Ω unless otherwise specified. Limits apply for TA =
25°C.
LM4951A
Units
(Limits)
Parameter
Test Conditions
Typ(3)
Limit(4)
4.5
5
IDD
Quiescent Power Supply Current
Shutdown Current
VIN = 0V, IO = 0A, RL = 8Ω BTL
VSD = GND(5)
2.5
0.01
5
mA (max)
µA (max)
mV (max)
V (min)
ISD
VOS
Output Offset Voltage
Shutdown Voltage Input High
Shutdown Voltage Input Low
Pull-down Resistor on SD pin
Wake-up Time
30
VSDIH
VSDIL
RPULLDOWN
TWU
1.2
0.4
45
V (max)
75
25
kΩ (min)
ms (max)
ms (max)
CB = 1.0µF
CB = 1.0µF
35
TSD
Shutdown time
10
150
190
°C (min)
°C (max)
TSD
PO
Thermal Shutdown Temperature
Output Power
170
1.8
THD = 1% (max); f = 1kHz
RL = 8Ω Mono BTL
1.5
0.5
W (min)
% (max)
%
PO = 600mWRMS; f = 1kHz
AV-BTL = 6dB
0.07
0.35
10
THD+N
Total Harmonic Distortion + Noise
PO = 600mWRMS; f = 1kHz
AV-BTL = 26dB
A-Weighted Filter, Ri = Rf = 20kΩ
Input Referred(6)
εOS
Output Noise
µV
VRIPPLE = 200mVp-p, f = 217Hz,
CB = 1.0μF, Input Referred
PSRR
Power Supply Rejection Ratio
66
56
dB (min)
(1) “Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur, including inoperability and degradation of
device reliability and/or performance. Functional operation of the device and/or non-degradation at the s or other conditions beyond
those indicated in the Recommended Operating Conditions is not implied. The Recommended Operating Conditionsindicate conditions
at which the device is functional and the device should not be operated beyond such conditions. All voltages are measured with respect
to the ground pin, unless otherwise specified.
(2) The Electrical Characteristics tables list ensured specifications under the listed Recommended Operating Conditions except as
otherwise modified or specified by the Electrical Characteristics Conditions and/or Notes. Typical specifications are estimations only and
are not ensured.
(3) Typical values represent most likely parametric norms at TA = +25ºC, and at the Recommended Operation Conditions at the time of
product characterization and are not specified.
(4) Datasheet min/max specification limits are ensured by test or statistical analysis.
(5) 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.
(6) Noise measurements are dependent on the absolute values of the closed loop gain setting resistors (input and feedback resistors).
4
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM4951A
LM4951A
www.ti.com
SNAS453C –AUGUST 2008–REVISED APRIL 2013
Electrical Characteristics VDD = 3.3V(1)(2)
The following specifications apply for VDD = 3.3V, AV-BTL = 6dB, RL = 8Ω unless otherwise specified. Limits apply for TA =
25°C.
LM4951A
Units
(Limits)
Parameter
Test Conditions
Typ(3)
Limit(4)
IDD
Quiescent Power Supply Current
Shutdown Current
VIN = 0V, IO = 0A, RL = 8Ω BTL
VSHUTDOWN = GND(5)
2.5
0.01
3
4.5
mA (max)
µA (max)
mV (max)
V (min)
ISD
2
VOS
VSDIH
VSDIL
TWU
TSD
Output Offset Voltage
Shutdown Voltage Input High
Shutdown Voltage Input Low
Wake-up Time
30
1.2
0.4
V (max)
ms
CB = 1.0µF
CB = 1.0µF
25
Shutdown time
10
ms (max)
THD = 1% (max); f = 1kHz
RL = 8Ω Mono BTL
PO
Output Power
280
230
mW (min)
% (max)
PO = 100mWRMS = 1kHz
AV-BTL = 6dB
0.07
0.5
THD+N
Total Harmonic Distortion + Noise
PO = 100mWRMS; f = 1kHz
AV-BTL = 26dB
0.35
10
%
µV
A-Weighted Filter, Ri = Rf = 20kΩ
Input Referred,(6)
εOS
Output Noise
VRIPPLE = 200mVp-p, f = 217Hz,
CB = 1μF, Input Referred
PSRR
Power Supply Rejection Ratio
71
61
dB (min)
(1) “Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur, including inoperability and degradation of
device reliability and/or performance. Functional operation of the device and/or non-degradation at the s or other conditions beyond
those indicated in the Recommended Operating Conditions is not implied. The Recommended Operating Conditionsindicate conditions
at which the device is functional and the device should not be operated beyond such conditions. All voltages are measured with respect
to the ground pin, unless otherwise specified.
(2) The Electrical Characteristics tables list ensured specifications under the listed Recommended Operating Conditions except as
otherwise modified or specified by the Electrical Characteristics Conditions and/or Notes. Typical specifications are estimations only and
are not ensured.
(3) Typical values represent most likely parametric norms at TA = +25ºC, and at the Recommended Operation Conditions at the time of
product characterization and are not specified.
(4) Datasheet min/max specification limits are ensured by test or statistical analysis.
(5) 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.
(6) Noise measurements are dependent on the absolute values of the closed loop gain setting resistors (input and feedback resistors).
Copyright © 2008–2013, Texas Instruments Incorporated
Submit Documentation Feedback
5
Product Folder Links: LM4951A
LM4951A
SNAS453C –AUGUST 2008–REVISED APRIL 2013
www.ti.com
Typical Performance Characteristics
THD+N vs Frequency
VDD = 3.3V, PO = 100mW, AV = 6dB
THD+N vs Frequency
VDD = 3.3V, PO = 100mW, AV = 26dB
10
5
10
1
2
1
0.5
0.2
0.1
0.1
0.01
0.05
0.02
0.01
20 50 100 200 500 1k 2k 5k 10k 20k
20
200
2k
20k
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 3.
Figure 4.
THD+N vs Frequency
VDD = 5V, PO = 400mW, AV = 6dB
THD+N vs Frequency
VDD = 5V, PO = 400mW, AV = 26dB
10
5
10
5
2
1
2
1
0.5
0.5
0.2
0.1
0.2
0.1
0.05
0.05
0.02
0.01
0.02
0.01
20 50 100 200 500 1k 2k 5k 10k 20k
20 50 100 200 500 1k 2k 5k 10k 20k
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 5.
Figure 6.
THD+N vs Frequency
VDD = 7.5V, PO = 600mW, AV = 6dB
THD+N vs Frequency
VDD = 7.5V, PO = 600mW, AV = 26dB
10
10
5
5
2
1
2
1
0.5
0.2
0.1
0.5
0.05
0.2
0.1
0.02
0.01
20 50 100 200 500 1k 2k 5k 10k 20k
20
200
2k
20k
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 7.
Figure 8.
6
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM4951A
LM4951A
www.ti.com
SNAS453C –AUGUST 2008–REVISED APRIL 2013
Typical Performance Characteristics (continued)
THD+N vs Output Power
VDD = 3.3V, f = 1kHz, AV = 6dB
THD+N vs Output Power
VDD = 3.3V, f = 1kHz, AV = 26dB
10
5
10
1
2
1
0.5
0.1
0.2
0.1
0.01
500m
100m
30m
10m
10m
30m 50m 70m100m
20m 40m 60m80m
300m 500m
200m 400m
OUTPUT POWER (W)
OUTPUT POWER (W)
Figure 9.
Figure 10.
THD+N vs Output Power
VDD = 5V, f = 1kHz, AV = 6dB
THD+N vs Output Power
VDD = 5V, f = 1kHz, AV = 26dB
10
5
10
5
2
1
2
1
0.5
0.2
0.1
0.5
0.05
0.2
0.1
0.02
0.01
10m 20m
50m 100m 200m 500m
1
10m 20m
50m 100m 200m 500m
OUTPUT POWER (W)
Figure 11.
1
OUTPUT POWER (W)
Figure 12.
THD+N vs Output Power
VDD = 7.5V, f = 1kHz, AV = 6dB
THD+N vs Output Power
VDD = 7.5V, f = 1kHz, AV = 26dB
10
5
10
5
2
1
2
1
0.5
0.2
0.1
0.5
0.05
0.2
0.1
0.02
0.01
10m 20m 50m100m 200m 500m
1
2
3
10m 20m 50m 100m 200m 500m
1
2
3
OUTPUT POWER (W)
OUTPUT POWER (W)
Figure 13.
Figure 14.
Copyright © 2008–2013, Texas Instruments Incorporated
Submit Documentation Feedback
7
Product Folder Links: LM4951A
LM4951A
SNAS453C –AUGUST 2008–REVISED APRIL 2013
www.ti.com
Typical Performance Characteristics (continued)
Power Supply Rejection vs Frequency
Power Supply Rejection vs Frequency
VDD = 3.3V, AV = 6dB, VRIPPLE = 200mVP-P
VDD = 3.3V, AV = 26dB, VRIPPLE = 200mVP-P
Input Terminated into 10Ω
Input Terminated into 10Ω
+0
-2.5
-5
+0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-7.5
-10
-12.5
-15
-17.5
-20
-22.5
-25
-27.5
-30
-32.5
-35
-37.5
-40
-42.5
-45
-47.5
-50
-52.5
-55
-57.5
-60
20 50 100 200 500 1k 2k
5k 10k 20k
20 50 100 200 500 1k 2k 5k 10k 20k
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 15.
Figure 16.
Power Supply Rejection vs Frequency
VDD = 5V, AV = 6dB, VRIPPLE = 200mVP-P
Input Terminated into 10Ω
+0
Power Supply Rejection vs Frequency
VDD = 5V, AV = 26dB, VRIPPLE = 200mVP-P
Input Terminated into 10Ω
+0
-2.5
-5
-10
-20
-30
-40
-50
-60
-70
-80
-90
-7.5
-10
-12.5
-15
-17.5
-20
-22.5
-25
-27.5
-30
-32.5
-35
-37.5
-40
-42.5
-45
-47.5
-50
-52.5
-55
-57.5
-60
-100
20 50 100 200 500 1k 2k
5k 10k 20k
20 50 100 200 500 1k 2k 5k 10k 20k
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 17.
Figure 18.
Power Supply Rejection vs Frequency
VDD = 7.5V, AV = 6dB, VRIPPLE = 200mVP-P
Input Terminated into 10Ω
+0
Power Supply Rejection vs Frequency
VDD = 7.5V, AV = 26dB, VRIPPLE = 200mVP-P
Input Terminated into 10Ω
+0
-2.5
-5
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-7.5
-10
-12.5
-15
-17.5
-20
-22.5
-25
-27.5
-30
-32.5
-35
-37.5
-40
-42.5
-45
-47.5
-50
-52.5
-55
-57.5
-60
20 50 100 200 500 1k 2k
5k 10k 20k
20 50 100 200 500 1k 2k 5k 10k 20k
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 19.
Figure 20.
8
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM4951A
LM4951A
www.ti.com
SNAS453C –AUGUST 2008–REVISED APRIL 2013
Typical Performance Characteristics (continued)
Noise Floor
VDD = 3.3V, AV = 6dB, Ri = Rf = 20kΩ
BW < 80kHz, A-weighted
Noise Floor
VDD = 3V, AV = 26dB, Ri = 20kΩ, Rf = 200kΩ
BW < 80kHz, A-weighted
50m
40m
30m
150m
20m
120m
100m
10m
9m
8m
7m
6m
5m
95m
90m
85m
82m
75m
72m
4m
3m
65m
62m
2m
55m
52m
50m
1m
20 50 100 200 500 1k 2k
5k 10k 20k
20 50 100 200 500 1k 2k
5k 10k 20k
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 21.
Figure 22.
Noise Floor
Noise Floor
VDD = 5V, AV = 6dB, Ri = Rf = 20kΩ
VDD = 5V, AV = 26dB, Ri = 20kΩ, Rf = 200kΩ
BW < 80kHz, A-weighted
BW < 80kHz, A-weighted
50m
40m
30m
150m
20m
120m
100m
10m
9m
8m
7m
6m
5m
95m
90m
85m
82m
75m
72m
4m
3m
65m
62m
2m
55m
52m
50m
1m
20 50 100 200 500 1k 2k
5k 10k 20k
20 50 100 200 500 1k 2k
5k 10k 20k
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 23.
Figure 24.
Noise Floor
Noise Floor
VDD = 7.5V, AV = 6dB, Ri = Rf = 20kΩ
VDD = 7.5V, AV = 26dB, Ri = 20kΩ, Rf = 200kΩ
BW < 80kHz, A-weighted
BW < 80kHz, A-weighted
50m
40m
30m
150m
20m
120m
100m
10m
9m
8m
7m
6m
5m
95m
90m
85m
82m
75m
72m
4m
3m
65m
62m
2m
55m
52m
50m
1m
20 50 100 200 500 1k 2k
5k 10k 20k
20 50 100 200 500 1k 2k
5k 10k 20k
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 25.
Figure 26.
Copyright © 2008–2013, Texas Instruments Incorporated
Submit Documentation Feedback
9
Product Folder Links: LM4951A
LM4951A
SNAS453C –AUGUST 2008–REVISED APRIL 2013
www.ti.com
Typical Performance Characteristics (continued)
Power Dissipation
vs Output Power
VDD = 3.3V, RL = 8Ω, f = 1kHz
Power Dissipation
vs Output Power
VDD = 7.5V, RL = 8Ω, f = 1kHz
1600
1400
1200
1000
800
600
400
200
0
300
250
200
150
100
50
0
0
50
100
150
200
250
300
0
200 400 600 800 1000 1200 1400
OUTPUT POWER (mW)
OUTPUT POWER (mW)
Figure 27.
Figure 28.
Clipping Voltage vs Supply Voltage
RL = 8Ω,
Supply Current
vs Supply Voltage
from top to bottom: Negative Voltage Swing; Positive
RL = 8Ω, VIN = 0V, Rsource = 50Ω
Voltage Swing
2.5
2
1.4
1.2
1
1.5
0.8
0.6
0.4
0.2
0
1
0.5
0
2
3
4
5
6
7
8
9
10
0
2
4
6
8
10
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
Figure 29.
Figure 30.
Output Power vs Supply Voltage
Output Power vs Load Resistance
VDD = 3.3V, f = 1kHz
from top to bottom: THD+N = 10%, THD+N = 1%
RL = 8Ω,
from top to bottom: THD+N = 10%, THD+N = 1%
450
4
400
350
300
250
200
150
100
50
3.5
3
2.5
2
1.5
1
0.5
0
0
0
20
40
60
80
100
2.7 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9
LOAD RESISTANCE (W)
SUPPLY VOLTAGE (V)
Figure 31.
Figure 32.
10
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM4951A
LM4951A
www.ti.com
SNAS453C –AUGUST 2008–REVISED APRIL 2013
Typical Performance Characteristics (continued)
Output Power vs Load Resistance
VDD = 7.5V, f = 1kHz
from top to bottom: THD+N = 10%, THD+N = 1%
Frequency Response vs Input Capacitor Size
RL = 8Ω
from top to bottom: Ci = 1.0µF, Ci = 0.39µF, Ci = 0.039µF
3000
2500
2000
1500
1000
500
20
16
12
8
4
0
-4
-8
-12
-16
-20
-24
-28
0
20
50 100 200 500 1k 2k
5k 10k 20k
8
16 32 48 64 80 96 112
LOAD RESISTANCE (W)
FREQUENCY (Hz)
Figure 33.
Figure 34.
Copyright © 2008–2013, Texas Instruments Incorporated
Submit Documentation Feedback
11
Product Folder Links: LM4951A
LM4951A
SNAS453C –AUGUST 2008–REVISED APRIL 2013
www.ti.com
APPLICATION INFORMATION
BRIDGE CONFIGURATION EXPLANATION
As shown in Figure 1, the LM4951A consists of two operational amplifiers that drive a speaker connected
between their outputs. 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 resistors set AMPB's gain to -1.
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 advantage of this phase difference, a load is placed
between AMPA and AMPB and driven differentially (commonly referred to as "bridge-tied load"). This results in a
differential, or BTL, gain of:
AVD = 2(Rf/ Ri) (V/V)
(1)
Bridge mode amplifiers are different from single-ended amplifiers that drive loads connected between a single
amplifier's output and ground. For a given supply voltage, bridge mode has an 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 signal is not clipped.
Under rare conditions, with unique combinations of high power supply voltage and high closed loop gain settings,
the LM4951A 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 amplifiers 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 increases internal IC power
dissipation and may permanently damage loads such as speakers.
POWER DISSIPATION
The LM4951A'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 (W)
(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 LM4951A's TJMAX = 150°C. In the SD package, the LM4951A'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 LM4951A's maximum
junction temperature.
TA = TJMAX - PDMAX-MONOBTLθJA (°C)
(4)
For a typical application with a 7.5V power supply and a BTL 8Ω load, the maximum ambient temperature that
allows maximum stereo power dissipation without exceeding the maximum junction temperature is 46°C for the
SD package.
TJMAX = PDMAX-MONOBTLθJA + TA (°C)
(5)
Equation 5 gives the maximum junction temperature TJMAX. If the result violates the LM4951A's maximum
junction temperature of 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.
12
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM4951A
LM4951A
www.ti.com
SNAS453C –AUGUST 2008–REVISED APRIL 2013
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, ensure 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 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 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 LM4951A'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 LM4951A's power supply pin and ground as short as possible. Connecting a larger 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,
system cost, and size constraints.
MICRO-POWER SHUTDOWN
The LM4951A features an active-low micro-power shutdown mode. When active, the LM4951A'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.
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.
As shown in Figure 1, the input resistor (Ri) and the input capacitor (Ci) create a high-pass filter. The cutoff
frequency can be found using Equation 6.
fc = 1/2πRiCi (Hz)
(6)
As an example when using a speaker with a low frequency limit of 50Hz, Ci, using Equation 6 is 0.159µF with Ri
set to 20kΩ. The values for Ci and Ri shown in Figure 1 allow the LM4951A to drive a high efficiency, full range
speaker whose response extends down to 20Hz.
Selecting Value A For RC
The LM4951A is designed for very fast turn on time. The CCHG pin allows the input capacitor to charge quickly to
improve click/pop performance. RC protects the CCHG pin 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 RC
is 1kΩ. If the input signal is less than VDD+0.3V and greater than -0.3V, and if the input signal is disabled when in
shutdown mode, RC may be shorted out.
OPTIMIZING CLICK AND POP REDUCTION PERFORMANCE
The LM4951A 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 LM4951A's internal amplifiers are
configured as unity gain buffers. 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.
Copyright © 2008–2013, Texas Instruments Incorporated
Submit Documentation Feedback
13
Product Folder Links: LM4951A
LM4951A
SNAS453C –AUGUST 2008–REVISED APRIL 2013
www.ti.com
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, there is a delay to prevent undesirable output transients (“click and
pops”). After this delay, the device becomes fully functional.
THERMAL SHUTDOWN AND SHORT CIRCUIT PROTECTION
The LM4951A has thermal shutdown and short circuit protection to fully protect the device. The thermal
shutdown circuit is activated when the die temperature exceeds a safe temperature. The short circuit protection
circuitry senses the output current. When the output current exceeds the threshold under a short condition, a
short will be detected and the output deactivated until the short condition is removed. If the output current is
lower than the threshold then a short will not be detected and the outputs will not be deactivated. Under such
conditions the die temperature will increase and, if the condition persist to raise the die temperature to the
thermal shutdown threshold, initiate a thermal shutdown response. Once the die cools the outputs will become
active.
RECOMMENDED PRINTED CIRCUIT BOARD LAYOUT
Figures 2–4 show the recommended two-layer PC board layout that is optimized for the SD10A. This circuit is
designed for use with an external 7.5V supply 8Ω (min) speakers.
Demonstration Board Circuit
Figure 35. Demo Board Circuit
14
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM4951A
LM4951A
www.ti.com
SNAS453C –AUGUST 2008–REVISED APRIL 2013
Demonstration Board Layout
Figure 36. Top Silkscreen
Figure 37. Top Layer
Copyright © 2008–2013, Texas Instruments Incorporated
Submit Documentation Feedback
15
Product Folder Links: LM4951A
LM4951A
SNAS453C –AUGUST 2008–REVISED APRIL 2013
www.ti.com
Figure 38. Bottom Layer
Table 1. Bill Of Materials
Bill Of Materials
Designator
RIN1
Value
20kΩ
200kΩ
100kΩ
1kΩ
Tolerance
1%
Part Description
1/8W, 0805 Resistor
Comments
R1
1%
1/8W, 0805 Resistor
RPULLUP
R2
1%
1/8W, 0805 Resistor
1%
1/8W, 0805 Resistor
R4, R5
CIN1
0Ω
1%
1/8W, 0805 Resistor
0.39μF
4.7μF
1μF
10%
10%
10%
Ceramic Capacitor, 25V, Size 1206
16V Tantalum Capacitor, Size A
16V Tantalum Capacitor, Size A
CSUPPLY
CBYPASS
C1
Not Used
0.100” 1x2 header, vertical mount
Input, Output, Vdd/GND Shutdown
DPR0010A package
U1
LM4951A, Mono, 1.8W, Audio Amplifier
16
Submit Documentation Feedback
Copyright © 2008–2013, Texas Instruments Incorporated
Product Folder Links: LM4951A
LM4951A
www.ti.com
SNAS453C –AUGUST 2008–REVISED APRIL 2013
REVISION HISTORY
Rev
Date
Description
1.0
08/13/08
09/05/08
Initial release.
Text edits.
1.01
Changes from Revision B (April 2013) to Revision C
Page
•
Changed layout of National Data Sheet to TI format .......................................................................................................... 16
Copyright © 2008–2013, Texas Instruments Incorporated
Submit Documentation Feedback
17
Product Folder Links: LM4951A
PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status Package Type Package Pins Package
Eco Plan
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
Samples
Drawing
Qty
(1)
(2)
(3)
(4/5)
(6)
LM4951ASD/NOPB
LM4951ASDX/NOPB
ACTIVE
ACTIVE
WSON
WSON
DPR
DPR
10
10
1000 RoHS & Green
4500 RoHS & Green
SN
Level-1-260C-UNLIM
Level-1-260C-UNLIM
-40 to 85
-40 to 85
4951ASD
4951ASD
SN
(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 <=1000ppm threshold. Antimony trioxide based
flame retardants must also meet the <=1000ppm threshold requirement.
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6)
Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two
lines if the finish value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 1
PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
Addendum-Page 2
PACKAGE MATERIALS INFORMATION
www.ti.com
5-Nov-2021
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
SPQ
Reel
Reel
A0
B0
K0
P1
W
Pin1
Diameter Width (mm) (mm) (mm) (mm) (mm) Quadrant
(mm) W1 (mm)
LM4951ASD/NOPB
LM4951ASDX/NOPB
WSON
WSON
DPR
DPR
10
10
1000
4500
178.0
330.0
12.4
12.4
4.3
4.3
4.3
4.3
1.3
1.3
8.0
8.0
12.0
12.0
Q1
Q1
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
5-Nov-2021
*All dimensions are nominal
Device
Package Type Package Drawing Pins
SPQ
Length (mm) Width (mm) Height (mm)
LM4951ASD/NOPB
LM4951ASDX/NOPB
WSON
WSON
DPR
DPR
10
10
1000
4500
208.0
367.0
191.0
367.0
35.0
35.0
Pack Materials-Page 2
PACKAGE OUTLINE
DPR0010A
WSON - 0.8 mm max height
SCALE 3.000
PLASTIC SMALL OUTLINE - NO LEAD
4.1
3.9
A
B
(0.2)
4.1
3.9
PIN 1 INDEX AREA
FULL R
BOTTOM VIEW
SIDE VIEW
20.000
ALTERNATIVE LEAD
DETAIL
0.8
0.7
C
SEATING PLANE
0.08 C
0.05
0.00
EXPOSED
THERMAL PAD
2.6 0.1
(0.1) TYP
SEE ALTERNATIVE
LEAD DETAIL
5
6
2X
3.2
11
3
0.1
8X 0.8
1
10
0.35
0.25
0.1
10X
0.5
0.3
PIN 1 ID
10X
C A B
C
0.05
4218856/B 01/2021
NOTES:
1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing
per ASME Y14.5M.
2. This drawing is subject to change without notice.
3. The package thermal pad must be soldered to the printed circuit board for thermal and mechanical performance.
www.ti.com
EXAMPLE BOARD LAYOUT
DPR0010A
WSON - 0.8 mm max height
PLASTIC SMALL OUTLINE - NO LEAD
(2.6)
10X (0.6)
SYMM
10
1
10X (0.3)
(1.25)
SYMM
11
(3)
8X (0.8)
6
5
(
0.2) VIA
TYP
(1.05)
(R0.05) TYP
(3.8)
LAND PATTERN EXAMPLE
EXPOSED METAL SHOWN
SCALE:15X
0.07 MIN
ALL AROUND
0.07 MAX
ALL AROUND
EXPOSED
METAL
EXPOSED
METAL
SOLDER MASK
OPENING
METAL UNDER
SOLDER MASK
METAL
EDGE
SOLDER MASK
OPENING
NON SOLDER MASK
DEFINED
SOLDER MASK
DEFINED
(PREFERRED)
SOLDER MASK DETAILS
4218856/B 01/2021
NOTES: (continued)
4. This package is designed to be soldered to a thermal pad on the board. For more information, see Texas Instruments literature
number SLUA271 (www.ti.com/lit/slua271).
www.ti.com
EXAMPLE STENCIL DESIGN
DPR0010A
WSON - 0.8 mm max height
PLASTIC SMALL OUTLINE - NO LEAD
SYMM
10X (0.6)
METAL
TYP
(0.68)
10
1
10X (0.3)
(0.76)
11
SYMM
8X (0.8)
4X
(1.31)
5
6
(R0.05) TYP
4X (1.15)
(3.8)
SOLDER PASTE EXAMPLE
BASED ON 0.125 mm THICK STENCIL
EXPOSED PAD 11:
77% PRINTED SOLDER COVERAGE BY AREA
SCALE:20X
4218856/B 01/2021
NOTES: (continued)
5. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate
design recommendations.
www.ti.com
IMPORTANT NOTICE AND DISCLAIMER
TI PROVIDES TECHNICAL AND RELIABILITY DATA (INCLUDING DATA SHEETS), DESIGN RESOURCES (INCLUDING REFERENCE
DESIGNS), APPLICATION OR OTHER DESIGN ADVICE, WEB TOOLS, SAFETY INFORMATION, AND OTHER RESOURCES “AS IS”
AND WITH ALL FAULTS, AND DISCLAIMS ALL WARRANTIES, EXPRESS AND IMPLIED, INCLUDING WITHOUT LIMITATION ANY
IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT OF THIRD
PARTY INTELLECTUAL PROPERTY RIGHTS.
These resources are intended for skilled developers designing with TI products. You are solely responsible for (1) selecting the appropriate
TI products for your application, (2) designing, validating and testing your application, and (3) ensuring your application meets applicable
standards, and any other safety, security, regulatory or other requirements.
These resources are subject to change without notice. TI grants you permission to use these resources only for development of an
application that uses the TI products described in the resource. Other reproduction and display of these resources is prohibited. No license
is granted to any other TI intellectual property right or to any third party intellectual property right. TI disclaims responsibility for, and you
will fully indemnify TI and its representatives against, any claims, damages, costs, losses, and liabilities arising out of your use of these
resources.
TI’s products are provided subject to TI’s Terms of Sale or other applicable terms available either on ti.com or provided in conjunction with
such TI products. TI’s provision of these resources does not expand or otherwise alter TI’s applicable warranties or warranty disclaimers for
TI products.
TI objects to and rejects any additional or different terms you may have proposed. IMPORTANT NOTICE
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2021, Texas Instruments Incorporated
相关型号：
©2020 ICPDF网 联系我们和版权申明