TI TPA302DR

TPA302
300-mW STEREO AUDIO POWER AMPLIFIER
SLOS174B – JANUARY 1997 – REVISE MARCH 2000
D
D
D
D
D
D
D
D PACKAGE
(TOP VIEW)
300-mW Stereo Output
PC Power Supply Compatibility 5-V and
3.3-V Specified Operation
Shutdown Control
Internal Mid-Rail Generation
Thermal and Short-Circuit Protection
Surface-Mount Packaging
Functional Equivalent of the LM4880
VO 1
SHUTDOWN
BYPASS
IN2
1
8
2
7
3
6
4
5
IN1
GND
VDD
VO 2
description
The TPA302 is a stereo audio power amplifier capable of delivering 250 mW of continuous average power into
an 8-Ω load at less than 0.06% THD + N from a 5-V power supply or up to 300 mW at 1% THD + N. The TPA302
has high current outputs for driving small unpowered speakers at 8 Ω or headphones at 32 Ω. For headphone
applications driving 32-Ω loads, the TPA302 delivers 60 mW of continuous average power at less than 0.06%
THD+ N. The amplifier features a shutdown function for power-sensitive applications as well as internal thermal
and short-circuit protection. The amplifier is available in an 8-pin SOIC (D) package that reduces board space
and facilitates automated assembly.
typical application circuit
VDD 6
RF
Audio
Input
VDD
CS
VDD/2
RI
8
IN 1
3
BYPASS
4
IN 2
CI
VO1 1
–
+
CC
CB
Audio
Input
RI
CI
2
VO2 5
–
+
SHUTDOWN
CC
Bias
Control
7
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.
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
1
TPA302
300-mW STEREO AUDIO POWER AMPLIFIER
SLOS174B – JANUARY 1997 – REVISE MARCH 2000
AVAILABLE OPTIONS
PACKAGED DEVICES
TA
SMALL OUTLINE†
(D)
– 40°C to 85°C
TPA302D
† The D packages are available taped and reeled. To order a taped
and reeled part, add the suffix R (e.g., TPA302DR)
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)‡
Supply voltage, VDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 V
Input voltage , VI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to VDD + 0.3 V
Continuous total power dissipation . . . . . . . . . . . . . . . . . . . . Internally Limited (See Dissipation Rating Table)
Operating junction temperature range, TJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –40°C to 150° C
Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 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
POWER RATING
DERATING FACTOR
ABOVE TA = 25°C
TA = 70°C
POWER RATING
TA = 85°C
POWER RATING
D
731 mW
5.8 mW/°C
460 mW
380 mW
recommended operating conditions
MIN
MAX
Supply voltage, VDD
2.7
5.5
UNIT
V
Operating free-air temperature, TA
–40
85
°C
dc electrical characteristics at specified free-air temperature, VDD = 3.3 V (unless otherwise noted)
PARAMETER
IDD
VIO
Supply current
PSRR
Power supply rejection ratio
IDD(SD)
Quiescent current in shutdown
TEST CONDITION
MIN
Input offset voltage
VDD = 3.2 V to 3.4 V
TYP
MAX
2.25
5
mA
5
20
mV
55
UNIT
dB
0.6
20
µA
ac operating characteristics, VDD = 3.3 V, TA = 25°C, RL = 8 Ω (unless otherwise noted)
PARAMETER
TEST CONDITION
MIN
THD < 0.08%
PO
BOM
B1
Vn
2
Output power
Gain = –1,,
f = 1 kHz
TYP
THD < 1%
125
THD < 0.08%,
RL = 32 Ω
25
THD < 1%,
RL = 32 Ω
35
UNIT
mW
Maximum output power bandwidth
Gain = 10,
20
kHz
Unity gain bandwidth
Open loop
1.5
MHz
Channel separation
f = 1 kHz
75
dB
Supply ripple rejection ratio
f = 1 kHz
45
dB
Noise output voltage
Gain = –1
10
µVrms
POST OFFICE BOX 655303
1% THD
MAX
100
• DALLAS, TEXAS 75265
TPA302
300-mW STEREO AUDIO POWER AMPLIFIER
SLOS174B – JANUARY 1997 – REVISE MARCH 2000
dc electrical characteristics at specified free-air temperature, VDD = 5 V (unless otherwise noted)
PARAMETER
TEST CONDITION
IDD
VOO
Supply current
Output offset voltage
See Note 1
PSRR
Power supply rejection ratio
VDD = 4.9 V to 5.1 V
IDD(SD)
Quiescent current in shutdown
MIN
TYP
MAX
4
10
UNIT
mA
5
20
mV
65
dB
0.6
µA
ac operating characteristics, VDD = 5 V, TA = 25°C, RL = 8 Ω (unless otherwise noted)
PARAMETER
TEST CONDITION
MIN
TYP
THD < 0.06%
PO
BOM
B1
Vn
THD < 1%
Gain = –1,,
f = 1 kHz
Output power
MAX
UNIT
250
300
THD < 0.06%,
RL = 32 Ω
60
THD < 1%,
RL = 32 Ω
80
1% THD
mW
Maximum output power bandwidth
Gain = 10,
20
kHz
Unity gain bandwidth
Open loop
1.5
MHz
Channel separation
f = 1 kHz
75
dB
Supply ripple rejection ratio
f = 1 kHz
45
dB
Noise output voltage
Gain = –1
10
µVrms
typical application
RF
6
VDD
CB
Stereo Audio
Input
RI
8 IN1–
R
3 BYPASS
CI
CC
VO1
1
CB
From Shutdown
Control Circuit (TPA4860)
2
RI
L
RL
Bias
Control
RL
Stereo
4 IN2–
VO2 5
CC
CI
250 mW per Channel at RL = 8 Ω
60 mW per Channel at RL = 32 Ω
RF
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
3
TPA302
300-mW STEREO AUDIO POWER AMPLIFIER
SLOS174B – JANUARY 1997 – REVISE MARCH 2000
TYPICAL CHARACTERISTICS
Table of Graphs
FIGURE
THD + N
vs Frequency
1–3, 7–9,
13–15, 19–21
vs Output power
4–6, 10–12
16–18, 22–24
Total harmonic distortion plus noise
IDD
Supply current
vs Supply
y voltage
g
vs Free-air temperature
Vn
Output noise voltage
vs Frequency
Maximum package power dissipation
vs Free-air temperature
Power dissipation
vs Output power
30, 31
POmax
Maximum output power
vs Free-air temperature
32, 33
PO
Output power
vs Load resistance
vs Supply voltage
34
35
36
37
Crosstalk
vs Frequency
38, 39
Supply ripple rejection ratio
vs Frequency
40, 41
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
10
VCC = 5 V
PO = 250 mW
RL = 8 Ω
AV = –1 V/V
1
VO2
0.1
VO1
100
1k
10 k 20 k
THD + N – Total Harmonic Distortion Plus Noise – %
THD + N – Total Harmonic Distortion Plus Noise – %
29
Closed loop response
10
VCC = 5 V
PO = 250 mW
RL = 8 Ω
AV = – 5 V/V
1
VO2
VO1
0.1
0.010
20
100
Figure 1
Figure 2
POST OFFICE BOX 655303
1k
f – Frequency – Hz
f – Frequency – Hz
4
27, 28
Open loop response
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
0.010
20
25
26
• DALLAS, TEXAS 75265
10 k 20 k
TPA302
300-mW STEREO AUDIO POWER AMPLIFIER
SLOS174B – JANUARY 1997 – REVISE MARCH 2000
TYPICAL CHARACTERISTICS
10
VCC = 5 V
PO = 250 mW
RL = 8 Ω
AV = –10 V/V
1
VO1
VO2
0.1
0.010
20
100
1k
10 k 20 k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
THD + N – Total Harmonic Distortion Plus Noise – %
THD + N – Total Harmonic Distortion Plus Noise – %
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
10
VCC = 5 V
f = 20 Hz
RL = 8 Ω
AV = –1 V/V
1
0.1
VO2
VO1
0.010
0.01
0.1
f – Frequency – Hz
Figure 3
Figure 4
10
VCC = 5 V
f = 1 kHz
RL = 8 Ω
AV = –1 V/V
1
VO1
VO2
0.010
0.01
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
THD + N – Total Harmonic Distortion Plus Noise – %
THD + N – Total Harmonic Distortion Plus Noise – %
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
0.1
1
PO – Output Power – W
0.1
1
10
VCC = 5 V
f = 20 kHz
RL = 8 Ω
AV = –1 V/V
1
VO1
VO2
0.1
0.010
0.01
PO – Output Power – W
0.1
1
PO – Output Power – W
Figure 5
Figure 6
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
5
TPA302
300-mW STEREO AUDIO POWER AMPLIFIER
SLOS174B – JANUARY 1997 – REVISE MARCH 2000
TYPICAL CHARACTERISTICS
10
VCC = 5 V
PO = 60 mW
RL = 32 Ω
AV = –1 V/V
1
VO1
0.1
VO2
0.010
20
100
1k
10 k 20 k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
THD + N – Total Harmonic Distortion Plus Noise – %
THD + N – Total Harmonic Distortion Plus Noise – %
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
10
VCC = 5 V
PO = 60 mW
RL = 32 Ω
AV = –5 V/V
1
VO1
VO2
0.1
0.010
20
100
f – Frequency – Hz
Figure 7
VCC = 5 V
PO = 60 mW
RL = 32 Ω
AV = –10 V/V
1
VO1
VO2
0.1
1k
10 k 20 k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
THD + N – Total Harmonic Distortion Plus Noise – %
THD + N – Total Harmonic Distortion Plus Noise – %
10
100
10
VCC = 5 V
f = 20 Hz
RL = 32 Ω
AV = –1 V/V
1
VO2
0.1
VO1
0.010
0.01
f – Frequency – Hz
0.1
PO – Output Power – W
Figure 9
6
10 k 20 k
Figure 8
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
0.010
20
1k
f – Frequency – Hz
Figure 10
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
1
TPA302
300-mW STEREO AUDIO POWER AMPLIFIER
SLOS174B – JANUARY 1997 – REVISE MARCH 2000
TYPICAL CHARACTERISTICS
10
VCC = 5 V
f = 1 kHz
RL = 32 Ω
AV = –1 V/V
1
0.1
VO1
0.010
0.01
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
THD + N – Total Harmonic Distortion Plus Noise – %
THD + N – Total Harmonic Distortion Plus Noise – %
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
VO2
0.1
1
10
VCC = 5 V
f = 20 kHz
RL = 32 Ω
AV = –1 V/V
1
VO1
VO2
0.1
0.010
0.01
PO – Output Power – W
0.1
Figure 11
Figure 12
10
VCC = 3.3 V
PO = 100 mW
RL = 8 Ω
AV = –1 V/V
1
VO1
0.1
VO2
100
1k
10 k 20 k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
THD + N – Total Harmonic Distortion Plus Noise – %
THD + N – Total Harmonic Distortion Plus Noise – %
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
0.010
20
1
PO – Output Power – W
10
VCC = 3.3 V
PO = 100 mW
RL = 8 Ω
AV = –5 V/V
1
VO1
VO2
0.1
0.010
20
f – Frequency – Hz
100
1k
10 k 20 k
f – Frequency – Hz
Figure 13
Figure 14
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
7
TPA302
300-mW STEREO AUDIO POWER AMPLIFIER
SLOS174B – JANUARY 1997 – REVISE MARCH 2000
TYPICAL CHARACTERISTICS
10
VCC = 3.3 V
PO = 100 mW
RL = 8 Ω
AV = –10 V/V
1
VO1
VO2
0.1
0.010
20
100
1k
10 k 20 k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
THD + N – Total Harmonic Distortion Plus Noise – %
THD + N – Total Harmonic Distortion Plus Noise – %
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
10
VCC = 3.3 V
f = 20 Hz
RL = 8 Ω
AV = –1 V/V
1
0.1
VO1
VO2
0.010
0.01
f – Frequency – Hz
Figure 15
VCC = 3.3 V
f = 1 kHz
RL = 8 Ω
AV = –1 V/V
1
VO1
0.1
VO2
0.1
1
THD + N – Total Harmonic Distortion Plus Noise – %
THD + N – Total Harmonic Distortion Plus Noise – %
10
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
10
VCC = 3.3 V
f = 20 kHz
RL = 8 Ω
AV = –1 V/V
1
VO1
VO2
0.1
0.010
0.01
PO – Output Power – W
0.1
PO – Output Power – W
Figure 17
8
1
Figure 16
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
0.010
0.01
0.1
PO – Output Power – W
Figure 18
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
1
TPA302
300-mW STEREO AUDIO POWER AMPLIFIER
SLOS174B – JANUARY 1997 – REVISE MARCH 2000
TYPICAL CHARACTERISTICS
10
VCC = 3.3 V
PO = 25 mW
RL = 32 Ω
AV = –1 V/V
1
VO2
0.1
VO1
0.010
20
100
1k
10 k 20 k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
THD + N – Total Harmonic Distortion Plus Noise – %
THD + N – Total Harmonic Distortion Plus Noise – %
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
10
VCC = 3.3 V
PO = 25 mW
RL = 32 Ω
AV = –5 V/V
1
VO1
VO2
0.1
0.010
20
100
f – Frequency – Hz
Figure 19
VCC = 3.3 V
PO = 25 mW
RL = 32 Ω
AV = –10 V/V
1
VO1
VO2
0.1
1k
10 k 20 k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
THD + N – Total Harmonic Distortion Plus Noise – %
THD + N – Total Harmonic Distortion Plus Noise – %
10
100
10 k 20 k
Figure 20
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
0.010
20
1k
f – Frequency – Hz
10
VCC = 3.3 V
f = 20 Hz
RL = 32 Ω
AV = –1 V/V
1
VO2
0.1
VO1
0.010
0.01
f – Frequency – Hz
0.1
1
PO – Output Power – W
Figure 21
Figure 22
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
9
TPA302
300-mW STEREO AUDIO POWER AMPLIFIER
SLOS174B – JANUARY 1997 – REVISE MARCH 2000
TYPICAL CHARACTERISTICS
10
VCC = 3.3 V
f = 1 kHz
RL = 32 Ω
AV = –1 V/V
1
0.1
VO1
VO2
0.010
0.01
0.1
1
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
THD + N – Total Harmonic Distortion Plus Noise – %
THD + N – Total Harmonic Distortion Plus Noise – %
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
10
VCC = 3.3 V
f = 20 kHz
RL = 32 Ω
AV = –1 V/V
VO1
1
VO2
0.1
0.010
0.01
0.1
PO – Output Power – W
1
PO – Output Power – W
Figure 23
Figure 24
SUPPLY CURRENT DISTRIBUTION
vs
FREE-AIR TEMPERATURE
SUPPLY CURRENT
vs
SUPPLY VOLTAGE
6
5
TA = 25°C
5V
4.5
5
Max
5V
5V
I DD – Supply Current – mA
I DD – Supply Current – mA
Max
4
3.5
3
2.5
2
4
3
Typ
2
Typ
Typ
Min
Min
Max
Min
3.3 V
Max
Min
3.3 V
Typ
Max
Typ
Min
Typ
Max
Min
3.3 V
1
1.5
1
2.5
3
4.5
3.5
4
VDD – Supply Voltage – V
5
5.5
0
–50
50
75
–25
0
25
TA – Free-Air Temperature – °C
Figure 25
10
Figure 26
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
100
TPA302
300-mW STEREO AUDIO POWER AMPLIFIER
SLOS174B – JANUARY 1997 – REVISE MARCH 2000
TYPICAL CHARACTERISTICS
OUTPUT NOISE VOLTAGE
vs
FREQUENCY
OUTPUT NOISE VOLTAGE
vs
FREQUENCY
1000
1000
VCC = 3.3 V
V n – Output Noise Voltage – µ V
V n – Output Noise Voltage – µ V
VCC = 5 V
100
VO1
10
VO2
1
20
100
1k
100
10
1
20
10 k 20 k
100
f – Frequency – Hz
Figure 27
10 k 20 k
Figure 28
MAXIMUM PACKAGE POWER DISSIPATION
vs
FREE-AIR TEMPERATURE
POWER DISSIPATION
vs
OUTPUT POWER
1
0.75
VDD = 5 V
0.75
Power Dissipation – W
Maximum Package Power Dissipation – W
1k
f – Frequency – Hz
0.5
0.25
0.5
RL = 8 Ω
0.25
RL = 16 Ω
0
–25
0
25
50
75
100
125
150
175
Two Channels Active
0
0
TA – Free-Air Temperature – °C
Figure 29
0.5
0.25
PO – Output Power – W
0.75
Figure 30
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
11
TPA302
300-mW STEREO AUDIO POWER AMPLIFIER
SLOS174B – JANUARY 1997 – REVISE MARCH 2000
TYPICAL CHARACTERISTICS
POWER DISSIPATION
vs
OUTPUT POWER
MAXIMUM OUTPUT POWER
vs
FREE-AIR TEMPERATURE
0.3
160
VDD = 3.3 V
Two Channels Active
140
T A – Free-Air Temperature – °C
0.25
Power Dissipation – W
VDD = 5 V
Two Channels Active
0.2
RL = 8 Ω
0.15
0.1
RL = 16 Ω
0.05
RL = 16 Ω
120
RL = 8 Ω
100
80
60
40
0
0
0.05
0.15
0.25
0.2
0.1
PO – Output Power – W
0.3
20
0.35
0
0.25
0.5
PO max – Maximum Output Power – W
Figure 31
Figure 32
MAXIMUM OUTPUT POWER
vs
FREE-AIR TEMPERATURE
OUTPUT POWER
vs
LOAD RESISTANCE
400
350
RL = 16Ω
140
130
PO – Output Power – mW
TA – Free-Air Temperature – °C
150
RL = 8Ω
120
110
300
250
200
VDD = 5 V
150
100
VDD = 3.3 V
50
VDD = 3.3 V
Two Channels Active
100
0
0.075
0.15
PO max – Maximum Output Power – W
0.225
0
5
10
Figure 33
12
0.75
35
40
15
20
25 30
RL – Load Resistance – Ω
Figure 34
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
45
50
TPA302
300-mW STEREO AUDIO POWER AMPLIFIER
SLOS174B – JANUARY 1997 – REVISE MARCH 2000
TYPICAL CHARACTERISTICS
OUTPUT POWER
vs
SUPPLY VOLTAGE
OPEN LOOP RESPONSE
THD = 1%
Gain
60
350
0°
50
RL = 8 Ω
250
–20°
40
200
Phase
30
–40°
Phase
300
Gain – dB
PO – Output Power – mW
400
20°
70
450
20
–60°
150
10
100
RL = 32 Ω
–80°
0
50
–10
0
2.5
3
4.5
3.5
4
VDD – Supply Voltage – V
5
10
5.5
100
1k
10 k
100 k
1M
–100°
10 M 100 M
f – Frequency – Hz
Figure 35
Figure 36
CROSSTALK
vs
FREQUENCY
CLOSED LOOP RESPONSE
0
200°
20
Gain
–10
VDD = 5 V
Phase
–20
0
100°
Crosstalk – dB
0°
–20
Phase
Gain – dB
–30
–40
–50
V02 to V01
(b to a)
–60
–70
–100°
–40
–80
V01 to V02
(a to b)
–90
–60
10
100
1k
10 k
100 k
1M
–200°
10 M 100 M
–100
10
100
1k
10 k
100 k
f – Frequency – Hz
f – Frequency – Hz
Figure 37
Figure 38
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
13
TPA302
300-mW STEREO AUDIO POWER AMPLIFIER
SLOS174B – JANUARY 1997 – REVISE MARCH 2000
TYPICAL CHARACTERISTICS
CROSSTALK
vs
FREQUENCY
SUPPLY RIPPLE REJECTION RATIO
vs
FREQUENCY
0
– 10
Supply Ripple Rejection Ratio – dB
– 10
0
VDD = 3.3 V
– 20
Crosstalk – dB
– 30
– 40
– 50
V02 to V01
(b to a)
– 60
– 70
– 80
V01 to VO2
(a to b)
– 90
– 100
10
100
1k
VDD = 5 V
– 20
– 30
– 40
VO2
– 50
VO1
– 60
– 70
– 80
– 90
10 k
– 100
100
100 k
1k
f – Frequency – Hz
f – Frequency – Hz
Figure 39
Figure 40
SUPPLY RIPPLE REJECTION RATIO
vs
FREQUENCY
0
Supply Ripple Rejection Ratio – dB
– 10
VDD = 3.3 V
– 20
– 30
– 40
VO2
– 50
VO1
– 60
– 70
– 80
– 90
– 100
100
1k
10 k
f – Frequency – Hz
Figure 41
14
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
20 k
10 k
20 k
TPA302
300-mW STEREO AUDIO POWER AMPLIFIER
SLOS174B – JANUARY 1997 – REVISE MARCH 2000
APPLICATION INFORMATION
selection of components
Figure 42 is a schematic diagram of a typical application circuit.
50 kΩ
50 kΩ
VDD 6
VDD = 5 V
RF
CF
CS
VDD/2
Audio
Input
RI
8
IN 1
3
BYPASS
4
IN 2
CI
VO1 1
CC
RL
CB
Audio
Input
RI
VO2 5
CC
CI
RL
CF
RF
2
SHUTDOWN (see Note A)
Bias
Control
7
NOTE A: SHUTDOWN must be held low for normal operation and asserted high for shutdown mode.
Figure 42. TPA302 Typical Notebook Computer Application Circuit
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
15
TPA302
300-mW STEREO AUDIO POWER AMPLIFIER
SLOS174B – JANUARY 1997 – REVISE MARCH 2000
APPLICATION INFORMATION
gain setting resistors, RF and RI
ǒǓ
The gain for the TPA302 is set by resistors RF and RI according to equation 1.
Gain
+*
RF
(1)
RI
Given that the TPA302 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 RF increases. In
addition, a certain range of RF values is required for proper start-up operation of the 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 2.
Effective Impedance
+ RRF)RRI
F
(2)
I
As an example, consider an input resistance of 10 kΩ and a feedback resistor of 50 kΩ. The gain of the amplifier
would be – 5 and the effective impedance at the inverting terminal would be 8.3 kΩ, which is 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 RF above 50 kΩ the amplifier tends to become unstable due to a pole
formed from RF and the inherent input capacitance of the MOS input structure. For this reason, a small
compensation capacitor of approximately 5 pF should be placed in parallel with RF. This, in effect, creates a
low-pass filter network with the cutoff frequency defined in equation 3.
f c(lowpass)
+ 2 p R1 C
(3)
F F
For example if RF is 100 kΩ and CF is 5 pF then fc(lowpass) is 318 kHz, which is well outside of the audio range.
input capacitor, CI
In the typical application an input capacitor, CI, is required to allow the amplifier to bias the input signal to the
proper dc level for optimum operation. In this case, CI and RI form a high-pass filter with the corner frequency
determined in equation 4.
f c(highpass)
+ 2 p R1 C
(4)
I I
The value of CI is important to consider as it directly affects the bass (low frequency) performance of the circuit.
Consider the example where RI is 10 kΩ and the specification calls for a flat bass response down to 40 Hz.
Equation 4 is reconfigured as equation 5.
CI
+ 2pR f
1
(5)
I c(highpass)
In this example, CI is 0.40 µF so one would likely choose a value in the range of 0.47 µF to 1 µF. A further
consideration for this capacitor is the leakage path from the input source through the input network (RI, CI) and
the feedback resistor (RF) to the load. This leakage current creates a dc offset voltage at the input to the amplifier
that reduces useful headroom, especially in high-gain applications (> 10). 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 VDD/2, which is likely
higher than the source dc level. Please note that it is important to confirm the capacitor polarity in the application.
16
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
TPA302
300-mW STEREO AUDIO POWER AMPLIFIER
SLOS174B – JANUARY 1997 – REVISE MARCH 2000
APPLICATION INFORMATION
power supply decoupling, CS
The TPA302 is a high-performance CMOS audio amplifier that requires adequate power supply decoupling to
ensure that 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 VDD lead, works best. For
filtering lower-frequency noise signals, a larger aluminum electrolytic capacitor of 10 µF or greater placed near
the power amplifier is recommended.
midrail bypass capacitor, CB
The midrail bypass capacitor, CB, serves several important functions. During startup or recovery from shutdown
mode, CB determines the rate at which the amplifier starts up. This helps to push the start-up pop noise into
the subaudible range (so low it can not be heard). The second 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. The capacitor is fed from a 25-kΩ source inside the amplifier. To keep the start-up pop as low
as possible, the relationship shown in equation 6 should be maintained.
ǒ
CB
1
25 kΩ
1
v
Ǔ ǒC R Ǔ
(6)
I I
As an example, consider a circuit where CB is 0.1 µF, CI is 0.22 µF and RI is 10 kΩ. Inserting these values into
the equation 9 results in: 400 ≤ 454 which satisfies the rule. Bypass capacitor, CB, values of 0.1 µF to 1 µF
ceramic or tantalum low-ESR capacitors are recommended for the best THD and noise performance.
output coupling capacitor, CC
In the typical single-supply single-ended (SE) configuration, an output coupling capacitor (CC) is required to
block the dc bias at the output of the amplifier thus preventing dc currents in the load. As with the input coupling
capacitor, the output coupling capacitor and impedance of the load form a high-pass filter governed by
equation 7.
fc
+ 2 p R1 C
(7)
L C
The main disadvantage, from a performance standpoint, is that the load impedances are typically small, which
drives the low-frequency corner higher. Large values of CC are required to pass low frequencies into the load.
Consider the example where a CC of 68 µF is chosen and loads vary from 8 Ω, 32 Ω, and 47 kΩ. Table 1
summarizes the frequency response characteristics of each configuration.
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
17
TPA302
300-mW STEREO AUDIO POWER AMPLIFIER
SLOS174B – JANUARY 1997 – REVISE MARCH 2000
APPLICATION INFORMATION
Table 1. Common Load Impedances vs Low Frequency Output Characteristics in SE Mode
RL
CC
68 µF
LOWEST FREQUENCY
8Ω
32 Ω
68 µF
73 Hz
47,000 Ω
68 µF
0.05 Hz
293 Hz
As Table 1 indicates, most of the bass response is attenuated into 8-Ω loads while headphone response is
adequate and drive into line level inputs (a home stereo for example) is very good.
The output coupling capacitor required in single-supply SE mode also places additional constraints on the
selection of other components in the amplifier circuit. The rules described earlier still hold with the addition of
the following relationship:
ǒ
CB
1
25 kΩ
Ǔvǒ ǓƠ
1
CI RI
1
R LC C
(8)
shutdown mode
The TPA302 employs a shutdown mode of operation designed to reduce quiescent supply current, IDD(q), to
the absolute minimum level during periods of nonuse for battery-power conservation. For example, during
device sleep modes or when other audio-drive currents are used (i.e., headphone mode), the speaker drive is
not required. The SHUTDOWN input terminal should be held low during normal operation when the amplifier
is in use. Pulling SHUTDOWN high causes the outputs to mute and the amplifier to enter a low-current state,
IDD < 1 µA. SHUTDOWN should never be left unconnected because amplifier operation would be unpredictable.
using low-ESR capacitors
Low-ESR capacitors are recommended throughout this applications section. A real 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.
18
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
TPA302
300-mW STEREO AUDIO POWER AMPLIFIER
SLOS174B – JANUARY 1997 – REVISE MARCH 2000
APPLICATION INFORMATION
thermal considerations
A prime consideration when designing an audio amplifier circuit is internal power dissipation in the device. The
curve in Figure 43 provides an easy way to determine what output power can be expected out of the TPA302
for a given system ambient temperature in designs using 5-V supplies. This curve assumes no forced airflow
or additional heat sinking.
160
VDD = 5 V
Two Channels Active
TA – Free-Air Temperature – °C
140
RL = 16 Ω
120
RL = 8 Ω
100
80
60
40
20
0
0.5
0.25
PO max – Maximum Output Power – W
0.75
Figure 43. Free-Air Temperature Versus Maximum Output Power
5-V versus 3.3-V operation
The TPA302 was designed for operation over a supply range of 2.7 V to 5.5 V. This data sheet provides full
specifications for 5-V and 3.3-V operation since are considered to be the two most common standard voltages.
There are no special considerations for 3.3-V versus 5-V operation as far as supply bypassing, gain setting, or
stability. Supply current is slightly reduced from 3.5 mA (typical) to 2.5 mA (typical). The most important
consideration is that of output power. Each amplifier in the TPA302 can produce a maximum voltage swing of
VDD – 1 V. This means, for 3.3-V operation, clipping starts to occur when VO(PP) = 2.3 V as opposed when
VO(PP) = 4 V while operating at 5 V. The reduced voltage swing subsequently reduces maximum output power
into the load before distortion begins to become significant.
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
19
TPA302
300-mW STEREO AUDIO POWER AMPLIFIER
SLOS174B – JANUARY 1997 – REVISE MARCH 2000
MECHANICAL INFORMATION
D (R-PDSO-G**)
PLASTIC SMALL-OUTLINE PACKAGE
14 PINS SHOWN
0.050 (1,27)
0.020 (0,51)
0.014 (0,35)
14
0.010 (0,25) M
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°– 8°
A
0.044 (1,12)
0.016 (0,40)
Seating Plane
0.069 (1,75) MAX
0.010 (0,25)
0.004 (0,10)
PINS **
0.004 (0,10)
8
14
16
A MAX
0.197
(5,00)
0.344
(8,75)
0.394
(10,00)
A MIN
0.189
(4,80)
0.337
(8,55)
0.386
(9,80)
DIM
4040047 / D 10/96
NOTES: B.
C.
D.
E.
20
All linear dimensions are in inches (millimeters).
This drawing is subject to change without notice.
Body dimensions do not include mold flash or protrusion, not to exceed 0.006 (0,15).
Falls within JEDEC MS-012
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
IMPORTANT NOTICE
Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue
any product or service without notice, and advise customers to obtain the latest version of relevant information
to verify, before placing orders, that information being relied on is current and complete. All products are sold
subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those
pertaining to warranty, patent infringement, and limitation of liability.
TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in
accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent
TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily
performed, except those mandated by government requirements.
CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF
DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE (“CRITICAL
APPLICATIONS”). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, AUTHORIZED, OR
WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT DEVICES OR SYSTEMS OR OTHER
CRITICAL APPLICATIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO
BE FULLY AT THE CUSTOMER’S RISK.
In order to minimize risks associated with the customer’s applications, adequate design and operating
safeguards must be provided by the customer to minimize inherent or procedural hazards.
TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent
that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other
intellectual property right of TI covering or relating to any combination, machine, or process in which such
semiconductor products or services might be or are used. TI’s publication of information regarding any third
party’s products or services does not constitute TI’s approval, warranty or endorsement thereof.
Copyright  2000, Texas Instruments Incorporated