TPA721
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
SLOS231B NOVEMBER 1998 REVISED MARCH 2000
1
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
D
Fully Specified for 3.3-V and 5-V Operation
D
Wide Power Supply Compatibility
2.5 V 5.5 V
D
Output Power for R
L
= 8
700 mW at V
DD
= 5 V, BTL
250 mW at V
DD
= 3.3 V, BTL
D
Integrated Depop Circuitry
D
Thermal and Short-Circuit Protection
D
Surface-Mount Packaging
SOIC
PowerPAD
TM
MSOP
description
The TPA721 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 TPA721 can deliver 250-mW of
continuous power into a BTL 8-
load at less than 0.6% THD+N throughout voice band frequencies. Although
this device is characterized out to 20 kHz, its operation was 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 7
A during shutdown. The
TPA721 is available in an 8-pin SOIC surface-mount package and the surface-mount PowerPAD MSOP, which
reduces board space by 50% and height by 40%.
Audio
Input
Bias
Control
VDD
700 mW
6
5
7
VO+
VDD
1
2
4
BYPASS
IN
VDD/2
CI
RI
CS
CB
RF
SHUTDOWN
VO 8
GND
From System Control
3
IN+
+
+
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.
Copyright
2000, 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
2
3
4
8
7
6
5
SHUTDOWN
BYPASS
IN+
IN
V
O
GND
V
DD
V
O
+
D OR DGN PACKAGE
(TOP VIEW)
PowerPAD is a trademark of Texas Instruments.
TPA721
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
SLOS231B NOVEMBER 1998 REVISED MARCH 2000
2
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
AVAILABLE OPTIONS
PACKAGED DEVICES
MSOP
TA
SMALL OUTLINE
(D)
MSOP
(DGN)
MSOP
Symbolization
40
C to 85
C
TPA721D
TPA721DGN
ABC
In the D package, the maximum 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 and DGN packages are available taped and reeled. To order a taped and reeled part, add
the suffix R to the part number (e.g., TPA301DR).
Terminal Functions
TERMINAL
I/O
DESCRIPTION
NAME
NO.
I/O
DESCRIPTION
BYPASS
2
I
BYPASS is the tap to the voltage divider for internal mid-supply bias. This terminal should be connected
to a 0.1-
F to 2.2-
F capacitor when used as an audio amplifier.
GND
7
GND is the ground connection.
IN
4
I
IN is the inverting input. IN is typically used as the audio input terminal.
IN+
3
I
IN + is the noninverting input. IN + is typically tied to the BYPASS terminal.
SHUTDOWN
1
I
SHUTDOWN places the entire device in shutdown mode when held high (IDD < 7
A).
VDD
6
VDD is the supply voltage terminal.
VO+
5
O
VO+ is the positive BTL output.
VO
8
O
VO is the negative BTL output.
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
Supply voltage, V
DD
6 V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input voltage, V
I
0.3 V to V
DD
+0.3 V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Continuous total power dissipation
internally limited (see Dissipation Rating Table)
. . . . . . . . . . . . . . . . . . . . .
Operating free-air temperature range, T
A
40
C to 85
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating junction temperature range, T
J
40
C to 150
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage temperature range, T
stg
65
C to 150
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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
TA
25
C
DERATING FACTOR
TA = 70
C
TA = 85
C
D
725 mW
5.8 mW/
C
464 mW
377 mW
DGN
2.14 W
17.1 mW/
C
1.37 W
1.11 W
Please see the Texas Instruments document, PowerPAD Thermally Enhanced Package Application Report
(literature number SLMA002), for more information on the PowerPAD package. The thermal data was
measured on a PCB layout based on the information in the section entitled
Texas Instruments Recommended
Board for PowerPAD on page 33 of the before mentioned document.
recommended operating conditions
MIN
MAX
UNIT
Supply voltage, VDD
2.5
5.5
V
Operating free-air temperature, TA
40
85
C
TPA721
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
SLOS231B NOVEMBER 1998 REVISED MARCH 2000
3
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
electrical characteristics at specified free-air temperature, V
DD
= 3.3 V, T
A
= 25
C (unless otherwise
noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
VOO
Output offset voltage (measured differentially)
See Note 1
20
mV
PSRR
Power supply rejection ratio
VDD = 3.2 V to 3.4 V
85
dB
IDD
Supply current
BTL mode
1.25
2.5
mA
IDD(SD)
Supply current, shutdown mode (see Figure 4)
7
50
A
NOTE 1: At 3 V < VDD < 5 V the dc output voltage is approximately VDD/2.
operating characteristics, V
DD
= 3.3 V, T
A
= 25
C, R
L
= 8
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
PO
Output power, see Note 2
THD = 0.5%,
See Figure 9
250
mW
THD + N
Total harmonic distortion plus noise
PO = 250 mW,
f = 200 Hz to 4 kHz, See Figure 7
0.55%
BOM
Maximum output power bandwidth
Gain = 2,
THD = 2%, See Figure 7
20
kHz
B1
Unity-gain bandwidth
Open Loop,
See Figure 15
1.4
MHz
kSVR
Supply ripple rejection ratio
f = 1 kHz,
CB = 1
F, See Figure 2
79
dB
Vn
Noise output voltage
Gain = 1,
CB = 0.1
F, See Figure 19
17
V(rms)
NOTE 2: Output power is measured at the output terminals of the device at f = 1 kHz.
electrical characteristics at specified free-air temperature, V
DD
= 5 V, T
A
= 25
C (unless otherwise
noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
VOO
Output offset voltage (measured differentially)
20
mV
PSRR
Power supply rejection ratio
VDD = 4.9 V to 5.1 V
78
dB
IDD
Supply current
1.25
2.5
mA
IDD(SD)
Supply current, shutdown mode (see Figure 4)
50
100
A
operating characteristics, V
DD
= 5 V, T
A
= 25
C, R
L
= 8
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
PO
Output power
THD = 0.5%,
See Figure 13
700
mW
THD + N
Total harmonic distortion plus noise
PO = 250 mW,
f = 200 Hz to 4 kHz, See Figure 11
0.5%
BOM
Maximum output power bandwidth
Gain = 2,
THD = 2%, See Figure 11
20
kHz
B1
Unity-gain bandwidth
Open Loop,
See Figure 16
1.4
MHz
kSVR
Supply ripple rejection ratio
f = 1 kHz,
CB = 1
F, See Figure 2
80
dB
Vn
Noise output voltage
Gain = 1,
CB = 0.1
F, See Figure 20
17
V(rms)
The DGN package, properly mounted, can conduct 700 mW RMS power continuously. The D package can only conduct 350 mW RMS power
continuously wtih peaks to 700 mW.
TPA721
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
SLOS231B NOVEMBER 1998 REVISED MARCH 2000
4
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
PARAMETER MEASUREMENT INFORMATION
Audio
Input
Bias
Control
VDD
6
5
7
VO+
VDD
1
2
4
BYPASS
IN
VDD/2
CI
RI
CS
CB
RF
SHUTDOWN
VO 8
RL = 8
GND
3
IN+
+
+
Figure 1. BTL Mode Test Circuit
TYPICAL CHARACTERISTICS
Table of Graphs
FIGURE
kSVR
Supply ripple rejection ratio
vs Frequency
2
IDD
Supply current
vs Supply voltage
3, 4
PO
Output power
vs Supply voltage
5
PO
Output power
vs Load resistance
6
THD + N
Total harmonic distortion plus noise
vs Frequency
7, 8, 11, 12
THD + N
Total harmonic distortion plus noise
vs Output power
9, 10, 13, 14
Open loop gain and phase
vs Frequency
15, 16
Closed loop gain and phase
vs Frequency
17, 18
Vn
Output noise voltage
vs Frequency
19, 20
PD
Power dissipation
vs Output power
21, 22
TPA721
700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER
SLOS231B NOVEMBER 1998 REVISED MARCH 2000
5
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
TYPICAL CHARACTERISTICS
Figure 2
50
60
80
100
20
100
1k
30
20
f Frequency Hz
SUPPLY RIPPLE REJECTION RATIO
vs
FREQUENCY
0
10k
20k
10
40
70
90
VDD = 5 V
VDD = 3.3 V
RL = 8
CB = 1
F
BTL
k
SVR
Supply Ripple Rejection Ratio dB
Figure 3
VDD Supply Voltage V
SUPPLY CURRENT
vs
SUPPLY VOLTAGE
1.8
0.8
0.6
1
3
4
5.5
5
I DD
Supply Current mA
BTL
2.5
3.5
4.5
1.6
1.2
1.4
VDD Supply Voltage V
SUPPLY CURRENT
vs
SUPPLY VOLTAGE
20
10
0
3
4
3.5
4.5
60
5
30
SHUTDOWN = High
40
50
5.5
2.5
I DD
Supply Current
A
70
80
90
Figure 4
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