TPA751
更新时间：2024-09-18 02:16:32
品牌：TI
描述：700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS
概述
数据手册
替代型号TPA751 概述
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS 具有差动输入700毫瓦MONO低压音频功率放大器
TPA751 数据手册
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PDF下载TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
D OR DGN PACKAGE
D
D
Fully Specified for 3.3-V and 5-V Operation
(TOP VIEW)
Wide Power Supply Compatibility
2.5 V – 5.5 V
SHUTDOWN
BYPASS
IN+
V –
O
GND
1
2
3
4
8
7
6
5
D
D
D
Power Supply Rejection at 217 Hz
– 84 dB at V
– 81 dB at V
= 5 V
= 3.3 V
DD
DD
V
DD
IN–
V +
O
Output Power for R = 8 Ω
L
– 700 mW at V
– 250 mW at V
= 5 V
MicroStar Juniort (GQS) Package
DD
DD
= 3.3 V
(TOP VIEW)
Ultralow Supply Current in Shutdown
Mode . . . 1.5 nA
(E2)
(E3)
(E4)
(E5)
(A2)
V
GND
V
V
–
SHUTDOWN
BYPASS
IN+
O
(A3)
(A4)
(A5)
D
Thermal and Short-Circuit Protection
DD
+
IN–
O
D
Surface-Mount Packaging
– SOIC
– PowerPAD MSOP
– MicroStar Junior (BGA)
(SIDE VIEW)
NOTE: The shaded terminals are used for thermal
connections to the ground plane.
description
The TPA751 is a bridge-tied load (BTL) audio power amplifier developed especially for low-voltage applications
where internal speakers are required. Operating with a 3.3-V supply, the TPA751 can deliver 250-mW of
continuous power into a BTL 8-Ω load at less than 0.6% THD+N throughout voice band frequencies. Although
this device is characterized out to 20 kHz, its operation is optimized for narrower band applications such as
wireless communications. The BTL configuration eliminates the need for external coupling capacitors on the
output in most applications, which is particularly important for small battery-powered equipment. This device
features a shutdown mode for power-sensitive applications with a supply current of 1.5 nA during shutdown.
The TPA751 is available in a 3.0 × 3.0 mm MicroStar Junior (BGA), 8-pin SOIC surface-mount package and
a surface-mount PowerPAD MSOP.
V
6
5
DD
V
R
DD
F
V
DD
/2
Audio
Input
C
S
R
I
IN –
IN+
4
3
V
+
O
–
+
C
I
2
BYPASS
C
B
700 mW
–
+
V
–
8
7
O
GND
SHUTDOWN
1
Bias
Control
From System Control
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.
PowerPAD and MicroStar Junior are trademarks of Texas Instruments.
Copyright 2002, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
AVAILABLE OPTIONS
PACKAGED DEVICES
‡
†
‡
MSOP
MicroStar-Junior (BGA)
(GQS)
SMALL OUTLINE
(D)
(DGN)
TPA751DGN
ATC
Device
TPA751GQS
TPA751
TPA751D
TPA751
Package symbolization
†
‡
In the SOIC package, the maximum RMS output power is thermally limited to 350 mW; 700 mW peaks can be driven, as long
as the RMS value is less than 350 mW.
The D, DGN, and GQS packages are available taped and reeled. To order a taped and reeled part, add the suffix R to the
part number (e.g., TPA751DR).
Terminal Functions
TERMINAL
NO.
D, DGN
I/O
DESCRIPTION
NAME
GQS
BYPASS is the tap to the voltage divider for internal mid-supply bias. This terminal should be
connected to a 0.1-µF to 2.2-µF capacitor when used as an audio amplifier.
BYPASS
E3
2
I
GND
§
7
4
3
1
6
5
8
GND is the ground connection.
IN–
E5
E4
E2
A4
A5
A2
I
I
I
IN– is the inverting input. IN– is typically used as the audio input terminal.
IN+ is the noninverting input. IN+ is typically tied to the BYPASS terminal for SE input.
IN+
SHUTDOWN
SHUTDOWN places the entire device in shutdown mode when held low (I = 1.5 nA).
DD
V
V
V
V
V
V
is the supply voltage terminal.
DD
DD
+
O
O
+ is the positive BTL output.
O
O
O
O
–
– is the negative BTL output.
§
A1, A3, A5, B1–B5, C1–C5, D1–D5 are electrical and thermal connections to the ground plane.
¶
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
Supply voltage, V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 V
DD
Input voltage, V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to V +0.3 V
I
DD
Continuous total power dissipation . . . . . . . . . . . . . . . . . . . . . Internally limited (see Dissipation Rating Table)
Operating free-air temperature range, T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –40°C to 85°C
Operating junction temperature range, T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –40°C to 150°C
A
J
Storage temperature range, T
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –65°C to 150°C
stg
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260°C
¶
Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
DISSIPATION RATING TABLE
PACKAGE
T
A
= 25°C
DERATING FACTOR
T
A
= 70°C
T = 85°C
A
||
||
GQS
D
1.66 W
725 mW
13.3 mW/°C
1.06 W
866 mW
377 mW
1.11 W
5.8 mW/°C
464 mW
1.37 W
#
DGN
2.14 W
17.1 mW/°C
#
||
See the Texas Instruments document, PowerPAD Thermally Enhanced Package Application Report
(SLMA002), for more information on the PowerPAD package. The thermal data was measured on a PCB
layoutbased on theinformation inthe sectionentitledTexasInstrumentsRecommendedBoardforPowerPAD
on page 33 of that document.
See the Texas Instruments document, MicroStar Junior Made Easy Application Brief (SSYA009A) for board
layout information on the MicroStar Junior package.
2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
recommended operating conditions
MIN
MAX
UNIT
V
Supply voltage, V
DD
2.5
5.5
High-level input voltage, V , (SHUTDOWN)
IH
0.9V
V
DD
Low-level input voltage, V , (SHUTDOWN)
IL
0.1V
V
DD
85
Operating free-air temperature, T
–40
°C
A
electrical characteristics at specified free-air temperature, V = 3.3 V, T = 25°C (unless otherwise
DD
A
noted)
PARAMETER
TEST CONDITIONS
MIN
TYP MAX
UNIT
mV
dB
|V
|
Output offset voltage (measured differentially)
Power supply rejection ratio
Supply current
SHUTDOWN = V , R = 8 Ω, RF = 10 kΩ
20
OS
PSRR
DD
L
V
DD
= 3.2 V to 3.4 V
85
1.25
I
I
SHUTDOWN = V , RF = 10 kΩ
DD
2.5
mA
nA
DD
Supply current, shutdown mode (see Figure 4) SHUTDOWN = 0 V, RF = 10 kΩ
1.5 1000
DD(SD)
|I
|I
|
SHUTDOWN, V
SHUTDOWN, V
= 3.3 V, V = V
1
1
µA
µA
IH
DD
DD
i
DD
|
= 3.3 V, V = 0 V
IL
i
operating characteristics, V
= 3.3 V, T = 25°C, R = 8 Ω
DD
A
L
PARAMETER
TEST CONDITIONS
See Figure 9
MIN
TYP MAX
UNIT
P
O
Output power, See Note 1
THD = 0.2%,
250
mW
THD + N Total harmonic distortion plus noise
P
O
= 250 mW, f = 200 Hz to 4 kHz, See Figure 7
0.55%
B
B
Maximum output power bandwidth
Unity-gain bandwidth
A
= –2 V/V,
THD = 2%,
See Figure 7
20
1.4
79
kHz
MHz
OM
V
Open loop,
f = 1 kHz,
See Figure 15
1
Supply ripple rejection ratio
Noise output voltage
C
C
= 1 µF,
See Figure 2
See Figure 19
dB
B
B
V
n
A
V
= –1V/V,
= 0.1 µF,
17
µV(rms)
NOTE 1: Output power is measured at the output terminals of the device at f = 1 kHz.
electrical characteristics at specified free-air temperature, V
noted)
= 5 V, T = 25°C (unless otherwise
A
DD
PARAMETER
TEST CONDITIONS
MIN
TYP MAX
UNIT
mV
dB
|V
|
Output offset voltage (measured differentially) SHUTDOWN = V , R = 8 Ω, RF = 10 kΩ
20
OS
PSRR
DD
L
Power supply rejection ratio
Supply current
V
DD
= 4.9 V to 5.1 V
78
I
SHUTDOWN = V , RF = 10 kΩ
DD
1.45
5
2.5
mA
nA
DD
I
Supply current, shutdown mode (see Figure 4) SHUTDOWN = 0 V, RF = 10 kΩ
1500
DD(SD)
|I
|I
|
SHUTDOWN, V
SHUTDOWN, V
= 5.5 V, V = V
1
1
µA
µA
IH
DD
DD
i
DD
|
= 5.5 V, V = 0 V
IL
i
operating characteristics, V
= 5 V, T = 25°C, R = 8 Ω
DD
A
L
PARAMETER
TEST CONDITIONS
See Figure 13
MIN
TYP MAX
UNIT
†
700
P
O
Output power
THD = 0.5%,
mW
THD + N Total harmonic distortion plus noise
P
= 250 mW, f = 200 Hz to 4 kHz, See Figure 11
0.5%
20
O
B
B
Maximum output power bandwidth
Unity-gain bandwidth
A
V
= –2 V/V,
THD = 2%,
See Figure 11
kHz
MHz
OM
Open loop,
f = 1 kHz,
See Figure 16
1.4
80
1
Supply ripple rejection ratio
Noise output voltage
C
C
= 1 µF,
See Figure 2
See Figure 20
dB
B
B
V
n
A
V
= –1 V/V,
= 0.1 µF,
17
µV(rms)
†
The GQS and DGN packages, properly mounted, can conduct 700 mW RMS power continuously. The D package, can only conduct 350 mW
RMS power continuously, with peaks to 700 mW.
3
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
PARAMETER MEASUREMENT INFORMATION
V
6
5
DD
V
DD
R
F
C
S
V
DD
/2
Audio
Input
R
I
IN –
4
3
V
O
+
–
C
IN+
I
+
2
BYPASS
R
L = 8 Ω
C
B
–
V
O
–
8
7
+
GND
SHUTDOWN
1
Bias
Control
V
DD
Figure 1. BTL Mode Test Circuit
TYPICAL CHARACTERISTICS
Table of Graphs
FIGURE
k
Supply ripple rejection ratio
Supply current
vs Frequency
2
SVR
I
vs Supply voltage
vs Supply voltage
vs Load resistance
vs Frequency
3, 4
DD
5
6
P
Output power
O
7, 8, 11, 12
THD+N
Total harmonic distortion plus noise
vs Output power
vs Frequency
9, 10, 13, 14
15, 16
Open loop gain and phase
Closed loop gain and phase
Output noise voltage
vs Frequency
17, 18
V
P
vs Frequency
19, 20
n
Power dissipation
vs Output power
21, 22
D
4
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
TYPICAL CHARACTERISTICS
SUPPLY RIPPLE REJECTION RATIO
SUPPLY CURRENT
vs
SUPPLY VOLTAGE
vs
FREQUENCY
0
–10
–20
1.8
1.6
1.4
1.2
R
C
= 8 Ω
= 1 µF
L
B
SHUTDOWN = V
RF = 10 kΩ
DD
Inputs Floating
–30
–40
–50
–60
–70
1
0.8
0.6
V
DD
= 3.3 V
–80
V
DD
= 5 V
1k
–90
–100
20
100
10k 20k
2.5
3
3.5
DD
4
4.5
5
5.5
f – Frequency – Hz
V
– Supply Voltage – V
Figure 2
Figure 3
SUPPLY CURRENT
vs
SUPPLY VOLTAGE
10
SHUTDOWN = 0 V
RF = 10 kΩ
9
8
7
6
5
4
3
2
1
0
2.5
3
3.5
DD
4
4.5
5
5.5
V
– Supply Voltage – V
Figure 4
5
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
TYPICAL CHARACTERISTICS
OUTPUT POWER
vs
SUPPLY VOLTAGE
1000
THD+N 1%
f = 1 kHz
800
600
R
= 8 Ω
L
400
200
0
R
= 32 Ω
L
2.5
3
3.5
4
4.5
5
5.5
V
DD
– Supply Voltage – V
Figure 5
OUTPUT POWER
vs
LOAD RESISTANCE
800
THD+N = 1%
f = 1 kHz
700
600
500
400
V
DD
= 5 V
300
200
V
DD
= 3.3 V
100
0
8
16
24
32
40
48
56
64
R
– Load Resistance – Ω
L
Figure 6
6
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
TYPICAL CHARACTERISTICS
TOTAL HARMONIC DISTORTION PLUS NOISE
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
vs
FREQUENCY
FREQUENCY
10
10
V
P
R
= 3.3 V
= 250 mW
= 8 Ω
DD
O
L
V
= 3.3 V
DD
R = 8 Ω
L
A
V
= –2 V/V
A
V
= –20 V/V
1
P
O
= 50 mW
1
A
V
=– 10 V/V
A
V
= –2 V/V
0.1
0.1
P
O
= 125 mW
P
O
= 250 mW
1k
0.01
0.01
20
100
1k
10k 20k
20
100
10k 20k
f – Frequency – Hz
f – Frequency – Hz
Figure 7
Figure 8
TOTAL HARMONIC DISTORTION PLUS NOISE
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
vs
OUTPUT POWER
OUTPUT POWER
10
10
V
= 3.3 V
DD
f = 1 kHz
= –2 V/V
A
V
f = 20 kHz
f = 10 kHz
1
1
f = 1 kHz
f = 20 Hz
R
= 8 Ω
L
0.1
0.1
V
R
C
= 3.3 V
= 8 Ω
= 1 µF
= –2 V/V
DD
L
B
A
V
0.01
0.01
0
0.05 0.1 0.15 0.2 0.25 0.3 0.35
– Output Power – W
0.4
0.01
0.1
1
P
O
P
O
– Output Power – W
Figure 9
Figure 10
7
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
TYPICAL CHARACTERISTICS
TOTAL HARMONIC DISTORTION PLUS NOISE
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
vs
FREQUENCY
FREQUENCY
10
10
V
P
R
= 5 V
= 700 mW
= 8 Ω
DD
O
L
V
R
A
V
= 5 V
DD
= 8 Ω
L
= –2 V/V
P
O
= 50 mW
A
V
= –20 V/V
1
1
A
V
= –10 V/V
P
O
= 700 mW
A
V
= –2 V/V
0.1
0.1
P
O
= 350 mW
0.01
0.01
20
100
1k
10k 20k
20
100
1k
10k 20k
f – Frequency – Hz
f – Frequency – Hz
Figure 11
Figure 12
TOTAL HARMONIC DISTORTION PLUS NOISE
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
vs
OUTPUT POWER
OUTPUT POWER
10
10
V
= 5 V
DD
f = 1 kHz
= –2 V/V
A
V
f = 20 kHz
f = 10 kHz
1
1
f = 1 kHz
R
= 8 Ω
L
f = 20 Hz
= 5 V
= 8 Ω
= 1 µF
0.1
0.1
V
R
C
DD
L
B
A
V
= –2 V/V
0.01
0.01
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
1
0.01
0.1
1
P
O
– Output Power – W
P
O
– Output Power – W
Figure 13
Figure 14
8
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
TYPICAL CHARACTERISTICS
OPEN-LOOP GAIN AND PHASE
vs
FREQUENCY
80
70
180°
V
R
= 3.3 V
= Open
DD
L
140°
100°
60
50
Phase
60°
20°
40
30
Gain
20
10
–20°
–60°
0
–100°
–140°
–180°
–10
–20
–30
1
10
2
10
3
10
4
10
1
f – Frequency – kHz
Figure 15
OPEN-LOOP GAIN AND PHASE
vs
FREQUENCY
80
70
60
50
40
30
20
10
0
180°
V
R
= 5 V
= Open
DD
L
140°
100°
Phase
60°
20°
Gain
–20°
–60°
–100°
–140°
–180°
–10
–20
–30
1
10
2
10
3
10
4
10
1
f – Frequency – kHz
Figure 16
9
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
TYPICAL CHARACTERISTICS
CLOSED-LOOP GAIN AND PHASE
vs
FREQUENCY
1
180°
170°
Phase
0.75
0.5
0.25
0
160°
150°
Gain
–0.25
–0.5
–0.75
–1
140°
130°
120°
V
= 3.3 V
DD
= 8 Ω
–1.25
–1.5
R
P
L
= 250 mW
O
–1.75
–2
1
2
10
3
10
4
10
5
10
6
10
10
f – Frequency – Hz
Figure 17
CLOSED-LOOP GAIN AND PHASE
vs
FREQUENCY
1
180°
170°
Phase
Gain
0.75
0.5
0.25
0
160°
150°
–0.25
–0.5
–0.75
–1
140°
130°
120°
V
R
= 5 V
= 8 Ω
= 700 m W
DD
L
–1.25
–1.5
P
O
–1.75
–2
1
2
10
3
10
4
10
5
10
6
10
10
f – Frequency – Hz
Figure 18
10
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
TYPICAL CHARACTERISTICS
OUTPUT NOISE VOLTAGE
OUTPUT NOISE VOLTAGE
vs
vs
FREQUENCY
FREQUENCY
100
100
V
= 3.3 V
V
= 5 V
DD
BW = 22 Hz to 22 kHz
DD
BW = 22 Hz to 22 kHz
R
A
= 8 Ω or 32 Ω
= –1 V/V
R
A
= 8 Ω or 32 Ω
= –1 V/V
L
V
L
V
V
O
BTL
V
BTL
O+
O
V
O+
V
10
10
1
20
1
20
100
1k
10k 20k
100
1k
10k 20k
f – Frequency – Hz
f – Frequency – Hz
Figure 19
Figure 20
POWER DISSIPATION
vs
OUTPUT POWER
POWER DISSIPATION
vs
OUTPUT POWER
350
300
250
200
150
100
800
V
DD
= 3.3 V
V
DD
= 5 V
R
= 8 Ω
R
= 8 Ω
700
600
500
400
300
200
L
L
R
= 32 Ω
L
R
= 32 Ω
L
50
0
100
0
0
200
400
600
0
200
400
600
800
1000
P
D
– Output Power – mW
P – Output Power – mW
D
Figure 21
Figure 22
11
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
APPLICATION INFORMATION
bridged-tied load
Figure 23showsalinearaudiopoweramplifier(APA)inaBTLconfiguration. TheTPA751BTLamplifierconsists
of two linear amplifiers driving both ends of the load. There are several potential benefits to this differential drive
configuration, but initially consider power to the load. The differential drive to the speaker means that as one
side is slewing up, the other side is slewing down, and vice versa. This, in effect, doubles the voltage swing on
the load as compared to a ground referenced load. Plugging 2 × V
is squared, yields 4× the output power from the same supply rail and load impedance (see equation 1).
into the power equation, where voltage
O(PP)
V
O(PP)
V
+
(rms)
Ǹ
2 2
2
V
(1)
(rms)
Power +
R
L
V
DD
V
O(PP)
2x V
R
O(PP)
L
V
DD
–V
O(PP)
Figure 23. Bridge-Tied Load Configuration
In a typical portable handheld equipment sound channel operating at 3.3 V, bridging raises the power into an
8-Ω speaker from a singled-ended (SE, ground reference) limit of 62.5 mW to 250 mW. In sound power that is
a 6-dB improvement, which is loudness that can be heard. In addition to increased power, there are frequency
response concerns. Consider the single-supply SE configuration shown in Figure 24. A coupling capacitor is
required to block the dc offset voltage from reaching the load. These capacitors can be quite large
(approximately 33 µF to 1000 µF), so they tend to be expensive, heavy, occupy valuable PCB area, and have
the additional drawback of limiting low-frequency performance of the system. This frequency-limiting effect, due
to the high pass filter network created with the speaker impedance and the coupling capacitance, is calculated
with equation 2.
1
(2)
f
+
c
2pR C
L C
12
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
APPLICATION INFORMATION
bridged-tied load (continued)
For example, a 68-µF capacitor with an 8-Ω speaker would attenuate low frequencies below 293 Hz. The BTL
configuration cancels the dc offsets, which eliminates the need for the blocking capacitors. Low-frequency
performance is then limited only by the input network and speaker response. Cost and PCB space are also
minimized by eliminating the bulky coupling capacitor.
V
DD
–3 dB
V
O(PP)
C
C
V
O(PP)
R
L
f
c
Figure 24. Single-Ended Configuration and Frequency Response
Increasing power to the load does carry a penalty of increased internal power dissipation. The increased
dissipation is understandable considering that the BTL configuration produces 4× the output power of a SE
configuration. Internal dissipation versus output power is discussed further in the thermal considerations
section.
BTL amplifier efficiency
The primary cause of linear amplifier inefficiencies is voltage drop across the output stage transistors. There
are two components of the internal voltage drop. One is the headroom or dc voltage drop that varies inversely
to output power. The second component is due to the sinewave nature of the output. The total voltage drop, can
be calculated by subtracting the RMS value of the output voltage from V . The internal voltage drop multiplied
DD
by the RMS value of the supply current, I rms, determines the internal power dissipation of the amplifier.
DD
An easy-to-use equation to calculate efficiency starts out being equal to the ratio of power from the power supply
to the power delivered to the load. To accurately calculate the RMS values of power in the load and in the
amplifier, the current and voltage waveform shapes must first be understood (see Figure 25).
I
V
O
DD
I
DD(RMS)
V
(LRMS)
Figure 25. Voltage and Current Waveforms for BTL Amplifiers
13
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
APPLICATION INFORMATION
BTL amplifier efficiency (continued)
Although the voltages and currents for SE and BTL are sinusoidal in the load, currents from the supply are very
different between SE and BTL configurations. In an SE application, the current waveform is a half-wave rectified
shape, whereas in BTL it is a full-wave rectified waveform. This means RMS conversion factors are different.
Keep in mind that for most of the waveform both the push and pull transistors are not on at the same time, which
supports the fact that each amplifier in the BTL device only draws current from the supply for half the waveform.
The following equations are the basis for calculating amplifier efficiency.
P
L
Efficiency of a BTL amplifier +
(3)
P
SUP
where
2
2
V rms
L
V
V
P
P
P
+
, and V
+
, therefore, P
+
L
LRMS
L
Ǹ
R
2R
2
L
L
p
2V
V
p
V
P
1
p
P
1
p
P
+
+
sin(t) dt
[cos(t)]
ŕ
P
+ V
I
avg
I
and
avg +
and
0
p R
SUP
DD DD
DD
R
R
L
L
0
L
therefore,
2 V
V
DD
P
P
+
SUP
p R
L
P = Power delivered to load
substituting P and P
into equation 7,
SUP
L
L
P
V
= Power drawn from power supply
= RMS voltage on BTL load
2
V
SUP
LRMS
P
R = Load resistance
L
2 R
p V
L
P
Efficiency of a BTL amplifier +
V = Peak voltage on BTL load
P
+
4 V
2 V
V
I
avg = Average current drawn from the
power supply
DD
DD
DD
P
p R
L
where
V
= Power supply voltage
= Efficiency of a BTL amplifier
DD
η
BTL
V
+
2 P R
Ǹ
P
L
L
therefore,
p
2 P R
Ǹ
L
L
h
+
BTL
(4)
4 V
DD
14
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
APPLICATION INFORMATION
application schematics
Figure 26 is a schematic diagram of a typical handheld audio application circuit, configured for a gain of
–10 V/V.
V
6
5
DD
R
50 kΩ
F
V
DD
C
S
V
DD
/2
Audio
Input
1 µF
R
10 kΩ
I
IN –
4
3
V
O
+
–
C
IN+
I
+
2
BYPASS
C
B
2.2 µF
700 mW
–
V
O
–
8
7
+
GND
SHUTDOWN
1
Bias
Control
From System Control
Figure 26. TPA751 Application Circuit
Figure 27 is a schematic diagram of a typical handheld audio application circuit, configured for a gain of
–10 V/V with a differential input.
V
6
5
DD
R
50 kΩ
F
V
DD
C
S
V
DD
/2
Audio
Input–
1 µF
R
10 kΩ
I
IN –
4
3
V
O
+
–
C
C
IN+
I
I
+
R
10 kΩ
R
F
I
Audio
Input+
50 kΩ
2
BYPASS
C
B
700 mW
–
V
O
–
8
7
2.2 µF
+
GND
SHUTDOWN
1
Bias
Control
From System Control
Figure 27. TPA751 Application Circuit With Differential Input
15
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
APPLICATION INFORMATION
application schematics (continued)
It is important to note that using the additional R resistor connected between IN+ and BYPASS causes V /2
F
DD
to shift slightly, which could influence the THD+N performance of the amplifier. Although an additional external
operational amplifier could be used to buffer BYPASS from R , tests in the lab have shown that the THD+N
F
performance is only minimally affected by operating in the fully differential mode as shown in Figure 27. The
following sections discuss the selection of the components used in Figures 26 and 27.
component selection
gain setting resistors, R and R
F
I
The gain for each audio input of the TPA751 is set by resistors R and R according to equation 5 for BTL mode.
F
I
R
F
BTL gain + * 2ǒ Ǔ
(5)
R
I
BTL mode operation brings about the factor 2 in the gain equation due to the inverting amplifier mirroring the
voltage swing across the load. Given that the TPA751 is a MOS amplifier, the input impedance is very high;
consequently input leakage currents are not generally a concern, although noise in the circuit increases as the
value of R increases. In addition, a certain range of R values is required for proper start-up operation of the
F
F
amplifier. Taken together it is recommended that the effective impedance seen by the inverting node of the
amplifier be set between 5 kΩ and 20 kΩ. The effective impedance is calculated in equation 6.
R R
F I
Effective impedance +
(6)
R ) R
F
I
As an example, consider an input resistance of 10 kΩ and a feedback resistor of 50 kΩ. The BTL gain of the
amplifier would be –10 V/V and the effective impedance at the inverting terminal would be 8.3 kΩ, which is well
within the recommended range.
For high performance applications, metal film resistors are recommended because they tend to have lower
noise levels than carbon resistors. For values of R above 50 kΩ, the amplifier tends to become unstable due
F
to a pole formed from R and the inherent input capacitance of the MOS input structure. For this reason, a small
F
compensation capacitor of approximately 5 pF should be placed in parallel with R when R is greater than
F
F
50 kΩ. This, in effect, creates a low-pass filter network with the cutoff frequency defined in equation 7.
–3 dB
1
(7)
f
+
c
2pR C
F F
f
c
For example, if R is 100 kΩ and C is 5 pF, then f is 318 kHz, which is well outside of the audio range.
F
F
c
16
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
APPLICATION INFORMATION
input capacitor, C
I
In the typical application an input capacitor, C , is required to allow the amplifier to bias the input signal to the
I
proper dc level for optimum operation. In this case, C and R form a high-pass filter with the corner frequency
I
I
determined in equation 8.
–3 dB
1
f
+
(8)
c
2pR C
I
I
f
c
The value of C is important to consider, as it directly affects the bass (low frequency) performance of the circuit.
I
Consider the example where R is 10 kΩ and the specification calls for a flat bass response down to 40 Hz.
I
Equation 8 is reconfigured as equation 9.
1
C +
(9)
I
2pR f
c
I
In this example, C is 0.40 µF, so one would likely choose a value in the range of 0.47 µF to 1 µF. A further
I
consideration for this capacitor is the leakage path from the input source through the input network (R , C ) and
I
I
thefeedbackresistor(R )totheload. Thisleakagecurrentcreatesadcoffsetvoltageattheinputtotheamplifier
F
that reduces useful headroom, especially in high gain applications. For this reason a low-leakage tantalum or
ceramic capacitor is the best choice. When polarized capacitors are used, the positive side of the capacitor
should face the amplifier input in most applications, as the dc level there is held at V /2, which is likely higher
DD
than the source dc level. It is important to confirm the capacitor polarity in the application.
power supply decoupling, C
S
The TPA751 is a high-performance CMOS audio amplifier that requires adequate power supply decoupling to
ensure the output total harmonic distortion (THD) is as low as possible. Power supply decoupling also prevents
oscillations for long lead lengths between the amplifier and the speaker. The optimum decoupling is achieved
by using two capacitors of different types that target different types of noise on the power supply leads. For
higher frequency transients, spikes, or digital hash on the line, a good low equivalent-series-resistance (ESR)
ceramic capacitor, typically 0.1 µF, placed as close as possible to the device V
lower-frequency noise signals, a larger aluminum electrolytic capacitor of 10µF orgreaterplacedneartheaudio
lead, works best. For filtering
DD
power amplifier is recommended.
17
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
APPLICATION INFORMATION
midrail bypass capacitor, C
B
The midrail bypass capacitor, C , is the most critical capacitor and serves several important functions. During
B
start-up or recovery from shutdown mode, C determines the rate at which the amplifier starts up. The second
B
function is to reduce noise produced by the power supply caused by coupling into the output drive signal. This
noise is from the midrail generation circuit internal to the amplifier, which appears as degraded PSRR and
THD + N. The capacitor is fed from a 250-kΩ source inside the amplifier. To keep the start-up pop as low as
possible, the relationship shown in equation 10 should be maintained. This insures the input capacitor is fully
charged before the bypass capacitor is fully charged and the amplifier starts up.
10
1
ǒCB 250 kΩǓ v ǒRF ) R Ǔ CI
(10)
I
As an example, consider a circuit where C is 2.2 µF, C is 0.47 µF, R is 50 kΩ, and R is 10 kΩ. Inserting these
B
I
F
I
values into the equation 10 we get:
18.2 v 35.5
whichsatisfiestherule.Bypasscapacitor,C ,valuesof0.1µFto2.2µFceramicortantalumlow-ESRcapacitors
B
are recommended for the best THD and noise performance.
using low-ESR capacitors
Low-ESR capacitors are recommended throughout this applications section. A real (as opposed to ideal)
capacitor can be modeled simply as a resistor in series with an ideal capacitor. The voltage drop across this
resistor minimizes the beneficial effects of the capacitor in the circuit. The lower the equivalent value of this
resistance, the more the real capacitor behaves like an ideal capacitor.
5-V versus 3.3-V operation
The TPA751 operates over a supply range of 2.5 V to 5.5 V. This data sheet provides full specifications for 5-V
and 3.3-V operation, as these are considered to be the two most common standard voltages. There are no
special considerations for 3.3-V versus 5-V operation with respect to supply bypassing, gain setting, or stability.
The most important consideration is that of output power. Each amplifier in TPA751 can produce a maximum
voltage swing of V
– 1 V. This means, for 3.3-V operation, clipping starts to occur when V
= 4 V at 5 V. The reduced voltage swing subsequently reduces maximum output power into
= 2.3 V as
DD
O(PP)
opposed to V
O(PP)
an 8-Ω load before distortion becomes significant.
Operation from 3.3-V supplies, as can be shown from the efficiency formula in equation 4, consumes
approximately two-thirds the supply power of operation from 5-V supplies for a given output-power level.
18
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
APPLICATION INFORMATION
headroom and thermal considerations
Linearpoweramplifiersdissipateasignificantamountofheatinthepackageundernormaloperatingconditions.
A typical music CD requires 12 dB to 15 dB of dynamic headroom to pass the loudest portions without distortion
as compared with the average power output. From the TPA751 data sheet, one can see that when the TPA751
is operating from a 5-V supply into an 8-Ω speaker that 700 mW peaks are available. Converting watts to dB:
P
700 mW
1 W
W
P
+ 10Log
+ 10Log
+ –1.5 dB
dB
P
ref
Subtracting the headroom restriction to obtain the average listening level without distortion yields:
–1.5 dB – 15 dB = –16.5 (15 dB headroom)
–1.5 dB – 12 dB = –13.5 (12 dB headroom)
–1.5 dB – 9 dB = –10.5 (9 dB headroom)
–1.5 dB – 6 dB = –7.5 (6 dB headroom)
–1.5 dB – 3 dB = –4.5 (3 dB headroom)
Converting dB back into watts:
PdBń10
P
+ 10
x P
W
ref
= 22 mW (15 dB headroom)
= 44 mW (12 dB headroom)
= 88 mW (9 dB headroom)
= 175 mW (6 dB headroom)
= 350 mW (3 dB headroom)
This is valuable information to consider when attempting to estimate the heat dissipation requirements for the
amplifier system. Comparing the absolute worst case, which is 700 mW of continuous power output with 0 dB
of headroom, against 12 dB and 15 dB applications drastically affects maximum ambient temperature ratings
for the system. Using the power dissipation curves for a 5-V, 8-Ω system, the internal dissipation in the TPA751
and maximum ambient temperatures is shown in Table 1.
Table 1. TPA751 Power Rating, 5-V, 8-Ω, BTL
D PACKAGE
(SOIC)
DGN PACKAGE
(MSOP)
GQS PACKAGE
(MicroStar Junior
PEAK OUTPUT
POWER
POWER
DISSIPATION
(mW)
)
AVERAGE
OUTPUT POWER
MAXIMUM AMBIENT
TEMPERATURE
MAXIMUM AMBIENT
TEMPERATURE
MAXIMUM AMBIENT
TEMPERATURE
(mW)
700
700
700
700
700
700 mW
675
595
475
350
225
34°C
47°C
68°C
89°C
111°C
110°C
115°C
122°C
125°C
125°C
99°C
105°C
114°C
123°C
125°C
350 mW (3 dB)
176 mW (6 dB)
88 mW (9 dB)
44 mW (12 dB)
Table 1 shows that the TPA751 can be used to its full 700-mW rating without any heat sinking in still air up to
110°C, 34°C, and 99°C for the DGN package (MSOP), D package (SOIC), and GQS (MicroStar Junior )
package, respectively.
19
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
MECHANICAL DATA
GQS (S-PBGA-N24)
PLASTIC BALL GRID ARRAY
3,20
2,80
2,00 TYP
0,50
E
D
C
B
A
3,20
2,80
2,00 TYP
1
2
3
4
5
(BOTTOM VIEW)
1,00 MAX
Seating Plane
0,08
0,35
0,25
0,21
0,11
M
0,05
4201012/A 04/00
NOTES: A. All linear dimensions are in millimeters.
B. This drawing is subject to change without notice.
C. MicroStar Junior configuration
20
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
MECHANICAL DATA
D (R-PDSO-G**)
PLASTIC SMALL-OUTLINE PACKAGE
14 PINS SHOWN
0.050 (1,27)
0.020 (0,51)
0.010 (0,25)
M
0.014 (0,35)
14
8
0.008 (0,20) NOM
0.244 (6,20)
0.228 (5,80)
0.157 (4,00)
0.150 (3,81)
Gage Plane
0.010 (0,25)
1
7
0°–ā8°
0.044 (1,12)
0.016 (0,40)
A
Seating Plane
0.004 (0,10)
0.010 (0,25)
0.004 (0,10)
0.069 (1,75) MAX
PINS **
8
14
16
DIM
0.197
(5,00)
0.344
(8,75)
0.394
(10,00)
A MAX
0.189
(4,80)
0.337
(8,55)
0.386
(9,80)
A MIN
4040047/D 10/96
NOTES: D. All linear dimensions are in inches (millimeters).
E. This drawing is subject to change without notice.
F. Body dimensions do not include mold flash or protrusion, not to exceed 0.006 (0,15).
G. Falls within JEDEC MS-012
21
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPA751
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
WITH DIFFERENTIAL INPUTS
SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002
MECHANICAL DATA
DGN (S-PDSO-G8)
PowerPAD PLASTIC SMALL-OUTLINE PACKAGE
0,38
0,25
0,65
M
0,25
8
5
Thermal Pad
(See Note D)
0,15 NOM
3,05
2,95
4,98
4,78
Gage Plane
0,25
0°–ā6°
1
4
0,69
0,41
3,05
2,95
Seating Plane
0,10
0,15
0,05
1,07 MAX
4073271/A 04/98
NOTES: A. All linear dimensions are in millimeters.
B. This drawing is subject to change without notice.
C. Body dimensions include mold flash or protrusions.
D. The package thermal performance may be enhanced by attaching an external heat sink to the thermal pad.
This pad is electrically and thermally connected to the backside of the die and possibly selected leads.
E. Falls within JEDEC MO-187
PowerPAD is a trademark of Texas Instruments.
22
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications,
enhancements, improvements, and other changes to its products and services at any time and to discontinue
any product or service without notice. Customers should obtain the latest relevant information before placing
orders and should verify that such information is current and complete. All products are sold subject to TI’s terms
and conditions of sale supplied at the time of order acknowledgment.
TI warrants performance of its hardware products to the specifications applicable at the time of sale in
accordance with TI’s standard warranty. Testing and other quality control techniques are used to the extent TI
deems necessary to support this warranty. Except where mandated by government requirements, testing of all
parameters of each product is not necessarily performed.
TI assumes no liability for applications assistance or customer product design. Customers are responsible for
their products and applications using TI components. To minimize the risks associated with customer products
and applications, customers should provide adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right,
copyright, maskworkright, orotherTIintellectualpropertyrightrelatingtoanycombination, machine, orprocess
in which TI products or services are used. Information published by TI regarding third–party products or services
does not constitute a license from TI to use such products or services or a warranty or endorsement thereof.
Use of such information may require a license from a third party under the patents or other intellectual property
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Reproduction of information in TI data books or data sheets is permissible only if reproduction is without
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Resale of TI products or services with statements different from or beyond the parameters stated by TI for that
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Mailing Address:
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Post Office Box 655303
Dallas, Texas 75265
Copyright 2002, Texas Instruments Incorporated
TPA751 替代型号
| 型号 | 制造商 | 描述 | 替代类型 | 文档 |
| TPA711 | TI | 700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER | 功能相似 |
|
| TPA701 | TI | 700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER | 功能相似 |
|
| TPA721 | TI | 700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER | 功能相似 |
|
TPA751 相关器件
| 型号 | 制造商 | 描述 | 价格 | 文档 |
| TPA751D | TI | 700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS | 获取价格 |
|
| TPA751DG4 | TI | 700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS | 获取价格 |
|
| TPA751DGN | TI | 700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS | 获取价格 |
|
| TPA751DGNG4 | TI | 700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS | 获取价格 |
|
| TPA751DGNR | TI | 700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS | 获取价格 |
|
| TPA751DGNRG4 | TI | 700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS | 获取价格 |
|
| TPA751DR | TI | 700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS | 获取价格 |
|
| TPA751DRG4 | TI | 700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS | 获取价格 |
|
| TPA751GQS | TI | 700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS | 获取价格 |
|
| TPA751GQSR | TI | Amplifier. Other | 获取价格 |
|
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