TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
D
D
D
D
D
D
Desktop Computer Amplifier Solution
– 1.75-W Bridge Tied Load (BTL) Center
Channel
– 500-mW L/R Single-Ended Channels
Low Distortion Output
– < 0.05% THD+N at Full Power
Full 3.3-V and 5-V Specifications
Surface-Mount Power Package
24-Pin TSSOP
L/R Input MUX Feature
Shutdown Control . . . IDD = 5 µA
CFC
RILC
CB
1
2
3
4
5
6
7
8
9
10
11
12
GND/HS
NC
LOUT
LLINEIN
LHPIN
CIN
VDD
SHUTDOWN
MUTE OUT
COUT+
MODE B
GND/HS
19
NC
CIN
GND/HS
NC
ROUT
RLINEIN
RHPIN
BYPASS
VDD
NC
HP/LINE
COUT–
MODE A
GND/HS
COUT+ 10
–
BYPASS
9
MUTE OUT
8
SHUTDOWN
MODE A 14
CNTL
MODE B 11
7, 18
HP/LINE 16
NC
RIR
20
21
RHPIN
RLINEIN
Internal
Speaker
COUT – 15
+
VDD
VDD
VDD
RM2
RM1
VDD
COUTR
Right
MUX
–
+
ROUT 22
RM3
CIR
NC
RIL
CIL
24
23
22
21
20
19
18
17
16
15
14
13
RFC
6
RIRC
PWP PACKAGE
(TOP VIEW)
RFR
5
LHPIN
4
LLINEIN
RFL
Left
MUX
–
+
LOUT 3
COUTL
GND/HS
1, 12, 13, 24
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 is a trademark of Texas Instruments Incorporated.
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.
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1
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
description
The TPA0103 is a 3-channel audio power amplifier in a 24-pin TSSOP thermal package primarily targeted at
desktop PC or notebook applications. The left/right (L/R) channel outputs are single ended (SE) and capable
of delivering 500 mW of continuous RMS power per channel into 4-Ω loads. The center channel output is a
bridged tied load (BTL) configuration for delivering maximum output power from PC power supplies. Combining
the SE line drivers and high power center channel amplifiers in a single TSSOP package simplifies design and
frees up board space for other features. Full power distortion levels of less than 0.25% THD+N into 4-Ω loads
from a 5-V supply voltage are typical. Low-voltage application are also well served by the TPA0103 providing
800 mW to the center channel into 4-Ω loads with a 3.3-V supply voltage.
Amplifier gain is externally configured by means of two resistors per input channel and does not require external
compensation for settings of 1 to 10. A two channel input MUX circuit is integrated on the L/R channel inputs
to allow two sets of stereo inputs to the amplifier. In the typical application, the center channel amplifier is driven
from a mix of the L/R inputs to produce a monaural representation of the stereo signal. The center channel
amplifier can be shut down independently of the L/R output for speaker muting in headphone applications. The
TPA0103 also features a full shutdown function for power sensitive applications holding the bias current
to 5 µA.
The PowerPAD package (PWP) delivers a level of thermal performance that was previously achievable only
in TO-220-type packages. Thermal impedances of less than 35°C/W are readily realized in multilayer PCB
applications. This allows the TPA0103 to operate at full power at ambient temperature of up to 85°C.
AVAILABLE OPTIONS
PACKAGE
TA
TSSOP†
(PWP)
– 40°C to 85°C
TPA0103PWP
† The PWP package is available in left-ended tape
and reel only (e.g., TPA0103PWPLE).
2
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TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
Terminal Functions
TERMINAL
NAME
BYPASS
NO.
I/O
19
DESCRIPTION
Bypass. BYPASS is a tap to the voltage divider for the internal mid-supply bias.
CIN
6
I
Center channel input
COUT+
10
O
Center channel + output. COUT+ is in an active or high-impedance state unless the device is in a mute state
when the MODE A terminal (14) is high and the MODE B terminal (11) is low.
COUT–
15
O
Center channel – output. COUT– is in an active or high-impedance state unless the device is in a mute state
when the MODE A terminal (14) is high and the MODE B terminal (11) is low.
GND/HS
1, 12,
13, 24
MODE A,
MODE B
14, 11
Ground. GND/HS is the ground connection for circuitry, directly connected to thermal pad.
I
Mode select. MODE A and MODE B determine the output modes of the TPA0103.
TERMINAL
3 CHANNEL
MUTE
CENTER
ONLY
L/R
ONLY
MODE A
L
MODE B
L
H
L
H
L
H
H
HP/LINE
16
I
Input MUX control input, hold high to select (L/R) HPIN (5, 20), hold low to select (L/R) LINEIN (4, 21). HP/LINE
is normally connected to ground when inputs are connected to (L/R) LINEIN.
LHPIN
5
I
Left channel headphone input, selected when the HP/LINE terminal (16) is held high
LLINEIN
4
I
Left channel line input, selected when the HP/LINE terminal (16) is held low
LOUT
3
O
Left channel output. LOUT is active when the MODE A terminal (14) is low and the MODE B terminal (11) is
don’t care.
MUTE OUT
9
O
When the MODE A terminal (14) is high and the MODE B terminal (11) is low, MUTE OUT is high and the device
is in a mute state. Otherwise MUTE OUT is low.
NC
2, 17,
23
RHPIN
20
RLINEIN
ROUT
SHUTDOWN
VDD
No internal connection
I
Right channel headphone input, selected when the HP/LINE terminal (16) is held high
21
I
Right channel line input, selected when the HP/LINE terminal (16) is held low
22
O
Right channel output. ROUT is active when the MODE A terminal (14) is low and the MODE B terminal (11)
is don’t care.
8
I
Places entire IC in shutdown mode when held high, IDD = 5 µA
7, 18
I
Supply voltage input. The VDD terminals must be connected together.
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3
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)†
Supply voltage, VDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 V
Continuous output current (COUT+, COUT–, LOUT, ROUT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 A
Continuous total power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . internally limited
Operating virtual junction temperature range, TJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 40°C to 150°C
Operating virtual case temperature range, TC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 40°C to 125°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
PWP‡
TA ≤ 25°C
2.7 W
DERATING FACTOR
21.8 mW/°C
TA = 70°C
1.7 W
TA = 85°C
1.4 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
Supply Voltage, VDD
NOM
MAX
5
5.5
3
Operating junction temperature, TJ
UNIT
V
°C
125
dc electrical characteristics, TA = 25°C
PARAMETER
TEST CONDITIONS
VDD = 5 V
IDD
Supply current
3V
VDD = 3
3.3
VOO
IDD(MUTE)
Output offset voltage (measured differentially)
Supply current in mute mode
VDD = 5 V,
VDD = 5 V
IDD(SD)
IDD in shutdown
VDD = 5 V
3 Channel
L and R or Center only
3 Channel
POST OFFICE BOX 655303
TYP
MAX
19
25
UNIT
mA
9
15
mA
13
20
mA
L and R or Center only
3
10
mA
Gain = 2,
5
35
mV
NOTE 1: At 3 V < VDD < 5 V the dc output voltage is approximately VDD/2.
4
NOM
• DALLAS, TEXAS 75265
See Note 1
µA
800
5
15
µA
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
ac operating characteristics, VDD = 5 V, TA = 25°C, RL = 4 Ω
PARAMETER
PO
TEST CONDITIONS
Output power (each channel) (see Note 2)
MIN
BTL,
Center channel
1.75
THD = 1%,
BTL,
Center channel
2.1
THD = 0.2%,
SE,
L/R channels
535
THD = 1%,
SE,
L/R channels
575
f = 20 to 20 kHz
THD+N
Total harmonic distortion plus noise
BOM
Maximum output power bandwidth
Po = 1.5 W,
G = 10,
Phase margin
Open loop
f = 1 kHz
f = 20 – 20 kHz
Center channel
60
L/R channels
30
Line/HP input separation
Input impedance
Vn
VO = 1 V(rms)
Output noise voltage
°
58
f = 1 kHz
Signal to noise ratio
Signal-to-noise
SE,
L/R channels
BTL,
Center channel
SE,
L/R channels
mW
85
L/R channels
Center channel
W
kHz
80
BTL,
UNIT
>20
Center channel
Mute attenuation
ZI
MAX
0.25%
THD < 5 %
Supply ripple rejection ratio
Channel-to-channel output separation
TYP
THD = 0.2%,
dB
85
dB
95
dB
100
dB
2
MΩ
94
dB
100
20
µV(rms)
9
NOTE 2: Output power is measured at the output terminals of the IC at 1 kHz.
ac operating characteristics, VDD = 3.3 V, TA = 25°C, RL = 4 Ω
PARAMETER
TEST CONDITIONS
BTL,
Center channel
800
THD = 1%
BTL,
Center channel
850
THD = 0.2%,
SE,
L/R channels
215
THD = 1%,
SE,
L/R channels
f = 20 to 20 kHz
Output power (each channel) (see Note 2)
THD+N
Total harmonic distortion plus noise
BOM
Maximum output power bandwidth
Po = 750 mW,
G = 10,
Phase margin
Open loop
f = 1 kHz
Supply ripple rejection ratio
f = 20 – 20 kHz
THD < 5 %
Signal to noise ratio
Signal-to-noise
Vn
Output noise voltage
VO = 1 V(rms)
kHz
85
°
62
Center channel
55
L/R channels
30
Input impedance
BTL,
Center channel
SE,
L/R channels
mW
>20
L/R channels
Line/HP input separation
UNIT
235
70
f = 1 kHz
MAX
0.8%
Center channel
Mute attenuation
ZI
TYP
THD = 0.2%
PO
Channel-to-channel output separation
MIN
dB
85
dB
95
dB
100
dB
2
MΩ
93
100
BTL,
Center channel
21
SE,
L/R channels
10
dB
µV(rms)
NOTE 2: Output power is measured at the output terminals of the IC at 1 kHz.
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5
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
PARAMETER MEASUREMENT INFORMATION
RF
CI
RL = 4 Ω or 8 Ω
RI
CB
4.7 µF
VDD
MODE A
VDD
MODE B
SHUTDOWN
MUX
HP/LINE
MUX
Figure 1. BTL Test Circuit
CB
4.7 µF
VDD
MODE A
VDD
MODE B
VDD
SHUTDOWN
RF
CI
CO
MUX
RI
RL
HP/LINE
CI
CO
MUX
RI
RL
RF
Figure 2. SE Test Circuit
6
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TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
TYPICAL CHARACTERISTICS
Table of Graphs
FIGURE
THD + N
vs Output power
3, 4, 7, 10–12, 15, 18, 21, 24,
27, 30, 33, 36
vs Frequency
5, 6, 8, 9, 13, 14, 16, 17, 19,
20, 22, 23, 25, 26, 28, 29, 31,
32, 34, 35
Total harmonic distortion plus noise
Vn
Output noise voltage
vs Frequency
37,38
Supply ripple rejection ratio
vs Frequency
39, 40
Crosstalk
vs Frequency
41, 42
Open loop response
vs Frequency
43, 44
Closed loop response
vs Frequency
45 – 48
Supply current
vs Supply voltage
49
PO
Output power
vs Supply voltage
vs Load resistance
50, 51
52, 53
PD
Power dissipation
vs Output power
54 – 57
IDD
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
10
THD+N –Total Harmonic Distortion + Noise – %
THD+N –Total Harmonic Distortion + Noise – %
10
VDD = 5 V
f = 1 kHz
BTL
1
RL = 4 Ω
RL = 8 Ω
0.1
VDD = 5 V
f = 1 kHz
SE
1
RL = 8 Ω
0.1
RL = 4 Ω
0.01
0.01
0
0.25 0.5 0.75
1
1.25 1.5 1.75
2
2.25 2.5
0
75 150 225 300 375 450 525 600 675 750
PO – Output Power – mW
PO – Output Power – W
Figure 3
Figure 4
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7
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
TYPICAL CHARACTERISTICS
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
VDD = 5 V
PO = 1.5 W
RL = 4 Ω
BTL
THD+N –Total Harmonic Distortion + Noise – %
THD+N –Total Harmonic Distortion + Noise – %
10
1
AV = –10 V/V
AV = –20 V/V
0.1
AV = –2 V/V
0.01
20
100
1k
10
VDD = 5 V
RL = 4 Ω
AV = –2 V/V
BTL
1
PO = 1.5 W
PO = 0.75 W
0.1
PO = 0.25 W
0.01
10 k 20 k
20
100
f – Frequency – Hz
Figure 5
THD+N –Total Harmonic Distortion + Noise – %
THD+N –Total Harmonic Distortion + Noise – %
10
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
VDD = 5 V
RL = 4 Ω
BTL
1
f = 20 kHz
0.1
f = 1 kHz
f = 20 Hz
10
VDD = 5 V
RL = 8 Ω
AV = –2 V/V
BTL
1
PO = 0.5 W
0.1
PO = 1 W
PO = 0.25 W
0.01
0.1
1
PO – Output Power – W
10
20
Figure 7
8
10 k 20 k
Figure 6
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
0.01
0.01
1k
f – Frequency – Hz
100
1k
f – Frequency – Hz
Figure 8
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10 k
20 k
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
TYPICAL CHARACTERISTICS
10
VDD = 5 V
PO = 1 W
RL = 8 Ω
BTL
1
AV = –20 V/V
AV = –10 V/V
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
THD+N –Total Harmonic Distortion + Noise – %
THD+N –Total Harmonic Distortion + Noise – %
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
0.1
AV = –2 V/V
0.01
20
100
1k
10 k
10
VDD = 5 V
RL = 8 Ω
AV = –2 V/V
BTL
1
f = 20 kHz
0.1
f = 1 kHz
f = 20 Hz
0.01
0.01
20 k
0.1
1
PO – Output Power – W
f – Frequency – Hz
Figure 9
Figure 10
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
10
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
THD+N –Total Harmonic Distortion + Noise – %
THD+N –Total Harmonic Distortion + Noise – %
10
VDD = 3.3 V
f = 1 kHz
BTL
1
RL = 4 Ω
RL = 8 Ω
0.1
0.01
10
VDD = 3.3 V
f = 1 kHz
SE
1
RL = 8 Ω
0.1
RL = 4 Ω
0.01
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
PO – Output Power – W
1
0
30
Figure 11
60
90 120 150 180 210 240 270 300
PO – Output Power – mW
Figure 12
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9
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
TYPICAL CHARACTERISTICS
10
VDD = 3.3 V
PO = 0.75 W
RL = 4 Ω
BTL
1
AV = –20 V/V
0.1
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
THD+N –Total Harmonic Distortion + Noise – %
THD+N –Total Harmonic Distortion + Noise – %
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
AV = –10 V/V
AV = –2 V/V
0.01
VDD = 3.3 V
RL = 4 Ω
AV = –2 V/V
BTL
1
PO = 0.75 W
0.1
PO = 0.1 W
PO = 0.35 W
0.01
20
100
10 k
1k
20 k
20
Figure 13
Figure 14
f = 20 kHz
f = 1 kHz
0.1
f = 20 Hz
10
VDD = 3.3 V
PO = 0.4 W
RL = 8 Ω
BTL
1
AV = –20 V/V
0.1
AV = –10 V/V
AV = –2 V/V
0.01
0.1
1
PO – Output Power – W
10
20
100
1k
f – Frequency – Hz
Figure 15
10
10 k 20 k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
THD+N –Total Harmonic Distortion + Noise – %
VDD = 3.3 V
RL = 4 Ω
AV = –2 V/V
BTL
0.01
0.01
1k
f – Frequency – Hz
10
1
100
f – Frequency – Hz
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
THD+N –Total Harmonic Distortion + Noise – %
10
Figure 16
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
10 k
20 k
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
TYPICAL CHARACTERISTICS
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
THD+N –Total Harmonic Distortion + Noise – %
THD+N –Total Harmonic Distortion + Noise – %
10
VDD = 3.3 V
RL = 8 Ω
AV = –2 V/V
BTL
1
0.1
PO = 0.25 W
PO = 0.4 W
PO = 0.1 W
0.01
20
100
1k
10
VDD = 3.3 V
RL = 8 Ω
AV = –2 V/V
BTL
f = 20 kHz
1
0.1
f = 1 kHz
f = 20 Hz
0.01
0.01
10 k 20 k
1
0.1
PO – Output Power – W
f – Frequency – Hz
Figure 17
Figure 18
VDD = 5 V
PO = 0.5 W
RL = 4 Ω
SE
1
AV = –10 V/V
0.1
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
THD+N –Total Harmonic Distortion + Noise – %
THD+N –Total Harmonic Distortion + Noise – %
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
10
10
AV = –5 V/V
AV = –1 V/V
10
VDD = 5 V
RL = 4 Ω
AV = –2 V/V
SE
1
PO = 0.5 W
PO = 0.25 W
0.1
PO = 0.1 W
0.01
0.01
20
100
1k
f – Frequency – Hz
10 k 20 k
20
100
1k
10 k 20 k
f – Frequency – Hz
Figure 19
Figure 20
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• DALLAS, TEXAS 75265
11
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
10
VDD = 5 V
RL = 4 Ω
AV = –2 V/V
SE
THD+N –Total Harmonic Distortion + Noise – %
THD+N –Total Harmonic Distortion + Noise – %
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
1
f = 20 kHz
0.1
f =100 Hz
f = 1 kHz
10
VDD = 5 V
PO = 0.25 W
RL = 8 Ω
SE
1
AV = –10 V/V
0.1
AV = –5 V/V
AV = –1 V/V
0.01
0.01
0.001
0.01
0.1
PO – Output Power – W
20
1
100
1k
Figure 21
Figure 22
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
10
VDD = 5 V
RL = 8 Ω
SE
THD+N –Total Harmonic Distortion + Noise – %
THD+N –Total Harmonic Distortion + Noise – %
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
1
0.1
PO = 0.25 W
PO = 0.1 W
PO = 0.05 W
0.01
20
100
10 k 20 k
1k
10
VDD = 5 V
RL = 8 Ω
AV = –2 V/V
SE
1
f = 20 kHz
0.1
f = 1 kHz
f = 100 Hz
0.01
0.001
f – Frequency – Hz
0.01
Figure 24
POST OFFICE BOX 655303
0.1
PO – Output Power – W
Figure 23
12
10 k 20 k
f – Frequency – Hz
• DALLAS, TEXAS 75265
1
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
TYPICAL CHARACTERISTICS
10
VDD = 5 V
PO = 75 mW
RL = 32 Ω
SE
1
AV = –10 V/V
AV = –5 V/V
0.1
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
THD+N –Total Harmonic Distortion + Noise – %
THD+N –Total Harmonic Distortion + Noise – %
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
AV = –1 V/V
0.01
VDD = 5 V
RL = 32 Ω
SE
1
0.1
PO = 50 mW
PO = 75 mW
PO = 25 mW
0.01
20
100
1k
10 k 20 k
f – Frequency – Hz
20
1k
f – Frequency – Hz
Figure 25
Figure 26
THD+N –Total Harmonic Distortion + Noise – %
10
VDD = 5 V
RL = 32 Ω
SE
1
f = 20 kHz
0.1
f = 20 Hz
f = 1 kHz
0.01
0.001
100
10 k 20 k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
THD+N –Total Harmonic Distortion + Noise – %
10
10
VDD = 3.3 V
PO = 0.2 W
RL = 4 Ω
SE
1
AV = –10 V/V
0.1
AV = –5 V/V
AV = –1 V/V
0.01
0.1
0.01
PO – Output Power – W
1
20
Figure 27
100
1k
f – Frequency – Hz
10 k 20 k
Figure 28
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TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
TYPICAL CHARACTERISTICS
10
VDD = 3.3 V
RL = 4 Ω
SE
1
PO = 0.2 W
PO = 0.1 W
0.1
PO = 0.05 W
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
THD+N –Total Harmonic Distortion + Noise – %
THD+N –Total Harmonic Distortion + Noise – %
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
100
1k
VDD = 3.3 V
RL = 4 Ω
AV = –2 V/V
SE
1
f = 20 kHz
f = 1 kHz
0.1
f = 100 Hz
0.01
0.001
0.01
20
10
10 k 20 k
0.01
f – Frequency – Hz
Figure 30
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
10
THD+N –Total Harmonic Distortion + Noise – %
THD+N –Total Harmonic Distortion + Noise – %
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
VDD = 3.3 V
PO = 100 mW
RL = 8 Ω
SE
1
AV = –10 V/V
0.1
AV = –1 V/V
10
VDD = 3.3 V
RL = 8 Ω
SE
1
PO = 100 mW
PO = 50 mW
0.1
PO = 25 mW
0.01
0.01
20
100
1k
f – Frequency – Hz
10 k 20 k
20
100
1k
f – Frequency – Hz
Figure 31
14
1
PO – Output Power – W
Figure 29
AV = –5 V/V
0.1
Figure 32
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10 k 20 k
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
TYPICAL CHARACTERISTICS
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
10
THD+N –Total Harmonic Distortion + Noise – %
THD+N –Total Harmonic Distortion + Noise – %
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
VDD = 3.3 V
RL = 8 Ω
SE
1
f = 20 kHz
f = 1 kHz
0.1
f = 100 Hz
0.01
0.001
10
VDD = 3.3 V
PO = 30 mW
RL = 32 Ω
SE
1
AV = –10 V/V
0.1
AV = –5 V/V
AV = –1 V/V
0.01
0.01
0.1
PO – Output Power – W
20
1
100
Figure 33
VDD = 3.3 V
RL = 32 Ω
SE
1
PO = 20 mW
PO = 30 mW
0.01
PO = 10 mW
0.001
100
1k
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
OUTPUT POWER
THD+N –Total Harmonic Distortion + Noise – %
THD+N –Total Harmonic Distortion + Noise – %
10
20
10 k 20 k
Figure 34
TOTAL HARMONIC DISTORTION PLUS NOISE
vs
FREQUENCY
0.1
1k
f – Frequency – Hz
10 k 20 k
10
VDD = 3.3 V
RL = 32 Ω
SE
1
f = 20 kHz
0.1
f = 1 kHz
f = 20 Hz
0.01
0.001
0.001
f – Frequency – Hz
Figure 35
0.01
0.1
PO – Output Power – W
1
Figure 36
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TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
TYPICAL CHARACTERISTICS
OUTPUT NOISE VOLTAGE
vs
FREQUENCY
OUTPUT NOISE VOLTAGE
vs
FREQUENCY
100
VDD = 5 V
BW = 22 Hz to 22 kHz
RL = 4Ω
V n – Output Noise Voltage – µ V(rms)
V n – Output Noise Voltage – µ V(rms)
100
Center
Left
10
Right
VDD = 3.3 V
BW = 22 Hz to 22 kHz
RL = 4Ω
Center
Left
10
Right
1
1
20
100
10 k 20 k
1k
20
100
f – Frequency – Hz
Figure 37
Figure 38
SUPPLY RIPPLE REJECTION RATIO
vs
FREQUENCY
SUPPLY RIPPLE REJECTION RATIO
vs
FREQUENCY
0
RL = 4 Ω
CB = 4.7 µF
BTL
–20
Supply Ripple Rejection Ratio – dB
Supply Ripple Rejection Ratio – dB
0
–10
–30
–40
–50
–60
VDD = 3.3 V
–70
–80
VDD = 5 V
–90
RL = 4 Ω
CB = 4.7 µF
SE
–10
–20
–30
–40
–50
VDD = 5 V
–60
–70
VDD = 3.3 V
–80
–90
–100
–100
20
100
1k
10 k 20 k
20
f – Frequency – Hz
100
1k
f – Frequency – Hz
Figure 39
16
10 k 20 k
1k
f – Frequency – Hz
Figure 40
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10 k 20 k
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
TYPICAL CHARACTERISTICS
CROSSTALK
vs
FREQUENCY
–40
CROSSTALK
vs
FREQUENCY
–40
VDD = 5 V
PO = 75 mW
RL = 32 Ω
SE
–50
–50
–60
Crosstalk – dB
–60
–70
–80
Left to Right
–90
–100
–70
Left to Right
–80
–90
–100
Right to Left
Right to Left
–110
–110
–120
100
1k
–120
20
10 k 20 k
f – Frequency – Hz
100
1k
10 k 20 k
f – Frequency – Hz
Figure 41
Figure 42
OPEN LOOP RESPONSE
100
VDD = 5 V
BTL
80
180°
60
Phase
90°
40
Phase
20
Gain – dB
Crosstalk – dB
VDD = 3.3 V
PO = 35 mW
RL = 32 Ω
SE
Gain
20
0°
0
–90°
–20
–40
0.01
0.1
1
10
100
1000
–180°
10000
f – Frequency – kHz
Figure 43
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TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
TYPICAL CHARACTERISTICS
OPEN LOOP RESPONSE
80
180°
VDD = 3.3 V
BTL
60
Phase
90°
Gain
0°
20
Phase
Gain – dB
40
0
–90°
–20
–40
0.01
0.1
1
10
100
1000
–180°
10000
f – Frequency – kHz
Figure 44
CLOSED LOOP RESPONSE
0°
10
VDD = 5 V
AV = –2 V/V
PO = 1.5 W
BTL
9
8
– 45°
7
– 90°
5
– 135°
4
Phase
– 180°
3
2
– 225°
1
0
20
100
1k
10 k
– 270°
100 k 200 k
f – Frequency – Hz
Figure 45
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Phase
Gain – dB
Gain
6
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
TYPICAL CHARACTERISTICS
CLOSED LOOP RESPONSE
0°
10
VDD = 3.3 V
AV = –2 V/V
PO = 0.75 W
BTL
9
8
– 45°
7
– 90°
5
– 135°
4
Phase
Gain – dB
Gain
6
Phase
– 180°
3
2
– 225°
1
0
20
100
1k
10 k
– 270°
100 k 200 k
f – Frequency – Hz
Figure 46
CLOSED LOOP RESPONSE
0°
0
Gain
–1
– 45°
–2
– 90°
–4
–5
– 135°
–6
Phase
Gain – dB
–3
Phase
– 180°
–7
VDD = 5 V
AV = –1 V/V
PO = 0.5 W
SE
–8
–9
–10
20
100
1k
10 k
– 225°
– 270°
100 k 200 k
f – Frequency – Hz
Figure 47
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TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
TYPICAL CHARACTERISTICS
CLOSED LOOP RESPONSE
0°
0
Gain
–1
– 45°
–2
– 90°
–4
–5
– 135°
–6
Phase
Gain – dB
–3
Phase
– 180°
–7
VDD = 3.3V
AV = –1 V/V
PO = 0.25 W
SE
–8
–9
–10
20
100
1k
10 k
– 225°
– 270°
100 k 200 k
f – Frequency – Hz
Figure 48
SUPPLY CURRENT
vs
SUPPLY VOLTAGE
OUTPUT POWER
vs
SUPPLY VOLTAGE
3
30
2.5
ÁÁ
ÁÁ
PO – Output Power – W
I DD – Supply Current – mA
25
20
3 Channel
15
10
L/R or Center
Channel
5
4
5
VDD – Supply Voltage – V
2
RL = 4 Ω
1.5
1
RL = 8 Ω
0.5
0
3
THD+N = 1%
BTL
Center Channel
6
0
2.5
3
4
4.5
Figure 50
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5
VDD – Supply Voltage – V
Figure 49
20
3.5
• DALLAS, TEXAS 75265
5.5
6
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
TYPICAL CHARACTERISTICS
OUTPUT POWER
vs
SUPPLY VOLTAGE
1
OUTPUT POWER
vs
LOAD RESISTANCE
3
THD+N = 1%
SE
Each L/R Channel
2.5
PO – Output Power – W
PO – Output Power – W
0.8
RL = 4 Ω
0.6
RL = 8 Ω
0.4
THD+N = 1%
BTL
Center Channel
0.2
2
1.5
VDD = 5 V
1
0.5
RL = 32 Ω
VDD = 3.3 V
0
0
2.5
3
3.5
4
4.5
5
VDD – Supply Voltage – V
5.5
0
6
4
Figure 51
1.4
RL = 4 Ω
1.2
PD – Power Dissipation – W
0.8
PO – Output Power – W
32
POWER DISSIPATION
vs
OUTPUT POWER
THD+N = 1%
SE
Each L/R Channel
0.6
0.4
28
Figure 52
OUTPUT POWER
vs
LOAD RESISTANCE
1
8
12
16
20
24
RL – Load Resistance – Ω
VDD = 5 V
1
0.8
RL = 8 Ω
0.6
0.4
0.2
VDD = 5 V
BTL
Center Channel
0.2
VDD = 3.3 V
0
0
0
4
8
12
16
20
24
RL – Load Resistance – Ω
28
32
0
Figure 53
1.5
0.5
1
PO – Output Power – W
2
Figure 54
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TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
TYPICAL CHARACTERISTICS
POWER DISSIPATION
vs
OUTPUT POWER
POWER DISSIPATION
vs
OUTPUT POWER
0.8
0.6
RL = 4 Ω
0.6
PD – Power Dissipation – W
PD – Power Dissipation – W
0.5
RL = 4 Ω
0.4
RL = 8 Ω
0.2
RL = 32Ω
VDD = 5 V
SE
Each L/R Channel
0.4
0.3
RL = 8 Ω
0.2
VDD = 3.3 V
BTL
Center Channel
0.1
0
0
0
0.1
0.4
0.2
0.3
PO – Output Power – W
0.5
0.6
0
0.75
0.25
0.5
PO – Output Power – W
Figure 55
Figure 56
POWER DISSIPATION
vs
OUTPUT POWER
0.6
PD – Power Dissipation – W
VDD = 3.3V
SE
Each L/R Channel
RL = 4 Ω
0.4
RL = 8 Ω
0.2
RL = 32Ω
0
0
0.05
0.1
0.15
0.2
PO – Output Power – W
Figure 57
22
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0.25
1
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
THERMAL INFORMATION
The thermally enhanced PWP package is based on the 24-pin TSSOP, but includes a thermal pad (see Figure 58)
to provide an effective thermal contact between the IC and the PWB.
Traditionally, surface mount and power have been mutually exclusive terms. A variety of scaled-down TO-220-type
packages have leads formed as gull wings to make them applicable for surface-mount applications. These packages,
however, have only two shortcomings: they do not address the very low profile requirements (< 2 mm) of many of
today’s advanced systems, and they do not offer a terminal-count high enough to accommodate increasing
integration. On the other hand, traditional low-power surface-mount packages require power-dissipation derating that
severely limits the usable range of many high-performance analog circuits.
The PowerPAD package (thermally enhanced TSSOP) combines fine-pitch surface-mount technology with thermal
performance comparable to much larger power packages.
The PowerPAD package is designed to optimize the heat transfer to the PWB. Because of the very small size and
limited mass of a TSSOP package, thermal enhancement is achieved by improving the thermal conduction paths that
remove heat from the component. The thermal pad is formed using a patented lead-frame design and manufacturing
technique to provide a direct connection to the heat-generating IC. When this pad is soldered or otherwise thermally
coupled to an external heat dissipator, high power dissipation in the ultra-thin, fine-pitch, surface-mount package can
be reliably achieved.
DIE
Side View (a)
Thermal
Pad
DIE
End View (b)
Bottom View (c)
Figure 58. Views of Thermally Enhanced PWP Package
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TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
APPLICATION INFORMATION
bridged-tied load versus single-ended mode
Figure 59 shows a linear audio power amplifier (APA) in a BTL configuration. The TPA0103 center -channel BTL
amplifier consists 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 × VO(PP) into the power
equation, where voltage is squared, yields 4× the output power from the same supply rail and load impedance
(see equation 1).
V (rms)
+ O(PP)
2 Ǹ2
Power
+
V
V (rms)
2
(1)
RL
VDD
VO(PP)
RL
2x VO(PP)
VDD
–VO(PP)
Figure 59. Bridge-Tied Load Configuration
In a typical computer sound channel operating at 5 V, bridging raises the power into an 8-Ω speaker from a
singled-ended (SE, ground reference) limit of 250 mW to 1 W. 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 of the L/R channels as shown in Figure 60. 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 is
due to the high pass filter network created with the speaker impedance and the coupling capacitance and is
calculated with equation 2.
24
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TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
APPLICATION INFORMATION
fc
+ 2 p R1 C
(2)
L C
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.
VDD
–3 dB
VO(PP)
fc = 293 Hz, 8 Ω, 68 µF
CC
RL
VO(PP)
fc = 73 Hz, 32 Ω, 68 µF
fc
Figure 60. Single-Ended Configuration and Frequency Response
BTL amplifier efficiency
Linear amplifiers are notoriously inefficient. The primary cause of these 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 VDD.
The internal voltage drop multiplied by the RMS value of the supply current, IDDrms, determines the internal
power dissipation of the amplifier.
An easy-to-use equation to calculate efficiency starts out as 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 61).
IDD
VO
IDD(RMS)
V(LRMS)
Figure 61. Voltage and Current Waveforms for BTL Amplifiers
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TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
APPLICATION INFORMATION
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.
Efficiency
+ PP L
(3)
SUP
Where:
+
P L(BTL)
V Lrms 2
RL
2
2 RL
, V PP
+ ǸPLRL2
V PP
2V PP
+ Ǹ2
V
V
P SUP + V DD I DDrms + DD PP
p RL
V PP
I DDrms +
pR
V Lrms(BTL)
+ 2 Ǹ2
+
V PP
V PP
V PP
2
Efficiency of a BTE Configuration
+P
SUP
+
+ VL
* VPP
Ǹ
L
PL
+ 2VP
V PP
2
2 RL
p RL
V DDV PP
LR L
+ 2VVPP p + p 22P
V
DD
(4)
DD
Equation 4 can also be used for SE operations.
Table 1 employs equation 4 to calculate efficiencies for four different output power levels. Note that the efficiency
of the amplifier is quite low for lower power levels and rises sharply as power to the load is increased resulting
in a nearly flat internal power dissipation over the normal operating range. Note that the internal dissipation at
full output power is less than in the half power range. Calculating the efficiency for a specific system is the key
to proper power supply design. For a stereo 1-W audio system with 8-Ω loads and a 5-V supply, the maximum
draw on the power supply is almost 3.25 W.
Table 1. Efficiency Vs Output Power in 5-V 8-Ω BTL Systems
OUTPUT POWER
(W)
EFFICIENCY
(%)
PEAK-TO-PEAK
VOLTAGE
(V)
INTERNAL
DISSIPATION
(W)
0.25
31.4
2.00
0.55
0.50
44.4
2.83
0.62
1.00
62.8
4.00
4.47†
0.59
1.25
70.2
† High peak voltages cause the THD to increase.
0.53
A final point to remember about linear amplifiers (either SE or BTL) is how to manipulate the terms in the
efficiency equation to utmost advantage when possible. Note that in equation 4, VDD is in the denominator. This
indicates that as VDD goes down, efficiency goes up. As the numerator values of RL and PL decrease, efficiency
decreases.
26
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TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
APPLICATION INFORMATION
For example, if the 5-V supply is replaced with a 3.3-V supply (TPA0103 has a maximum recommended VDD
of 5.5 V) in the calculations of Table 1 then efficiency at 0.5 W would rise from 44% to 67% and internal power
dissipation would fall from 0.62 W to 0.25 W at 5 V. Then for a stereo 0.5-W system from a 3.3-V supply, the
maximum draw would only be 1.5 W as compared to 2.24 W from 5 V. In other words, use the efficiency analysis
to chose the correct supply voltage and speaker impedance for the application.
selection of components
Figure 62 and Figure 63 are a schematic diagrams of typical computer application circuits.
CFC
RFC
6
RIRC
RILC
CB
19
NC
9
8
CIN
COUT+ 10
–
+
BYPASS
MODE A 14
MUTE OUT
CNTL
MODE B 11
SHUTDOWN
VDD
7, 18
HP/LINE 16
NC
RIR
20
21
RHPIN
RLINEIN
VDD
RM2
VDD 100 kΩ
RM1
100 kΩ
VDD
COUTR
Right
MUX
–
+
ROUT 22
RM3
1 kΩ
CIR
NC
RIL
CIL
Internal
Speaker
COUT – 15
RFR
5
LHPIN
4
LLINEIN
RFL
Left
MUX
–
+
LOUT 3
COUTL
GND/HS
1, 12, 13, 24
Figure 62. TPA0103 Minimum Configuration Application Circuit
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27
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
APPLICATION INFORMATION
CFC
5 pF
RFC 100 kΩ
RIC
10 kΩ
6
Mono
CIC
0.1 µF
19
CB
4.7 µF
AC97
VDD
11
System Active/Shutdown
16
Control
High/Low Gain
RIRHP
10 kΩ
Right
Line
7, 18
CIR
0.1 µF
CIN
COUT+ 10
–
BYPASS
4Ω
Internal
Speaker
COUT – 15
+
VDD
MODE A 14
MODE B
CNTL
HP/LINE
20
RHPIN
21
RLINEIN
RM2
100 kΩ
(see Note A)
VDD
RM1
100 kΩ
MUTE OUT 11
SHUTDOWN 8
Right
MUX
–
+
ROUT 22
COUTR
470 µF
RM3
1 kΩ
RIRL
10 kΩ
RFRHP
10 kΩ
4 Ω – 32 Ω
Speakers or
Headphones
RFRL
50 kΩ
RILHP
10 kΩ
Left
Line
CIL
0.1 µF
5
LHPIN
4
LLINEIN
Left
MUX
RILL
10 kΩ
LOUT 3
–
+
GND/HS
1, 12, 13, 24
RFLHP
10 kΩ
RFLL
50 kΩ
NOTE A: This connection is for ultralow current in shutdown mode.
Figure 63. TPA0103 Full Configuration Application Circuit
28
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
COUTL
470 µF
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
APPLICATION INFORMATION
gain setting resistors, RF and RI
ǒǓ
ǒǓ
The gain for each audio input of the TPA0103 is set by resistors RF and RI according to equation 5 for BTL mode.
+ *2
BTL Gain
RF
(5)
RI
In SE mode the gain is set by the RF and RI resistors and is shown in equation 6. Since the inverting amplifier
is not used to mirror the voltage swing on the load, the factor of 2, from equation 5, is not included.
SE Gain
+*
RF
(6)
RI
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 TPA0103 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 are required for proper startup 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 7.
Effective Impedance
+ RRF)RRI
F
(7)
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 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 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 when RF is greater than
50 kΩ. This, in effect, creates a low pass filter network with the cutoff frequency defined in equation 8.
–3 dB
f c(lowpass)
+ 2 p R1 C
(8)
F F
fc
For example, if RF is 100 kΩ and Cf is 5 pF then fc is 318 kHz, which is well outside of the audio range.
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
29
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
APPLICATION INFORMATION
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 9.
–3 dB
+ 2 p R1 C
f c(highpass)
(9)
I I
fc
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 8 is reconfigured as equation 10.
CI
+ 2 p 1R fc
(10)
I
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. 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.
power supply decoupling, CS
The TPA0103 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 VDD lead works best. For
filtering lower-frequency noise signals, a larger aluminum electrolytic capacitor of 10 µF or greater placed near
the audio power amplifier is recommended.
30
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
APPLICATION INFORMATION
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. 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 11 should be maintained.
ǒ
CB
ǓW v ǒC1R Ǔ
1
25 k
(11)
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 10 we get 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 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 12.
–3 dB
f c(high)
+ 2 p R1 C
(12)
L C
fc
The main disadvantage, from a performance standpoint, is the load impedances are typically small, which drives
the low-frequency corner higher degrading the bass response. Large values of CC are required to pass low
frequencies into the load. Consider the example where a CC of 330 µF is chosen and loads vary from 4 Ω, 8 Ω,
32 Ω, to 47 kΩ. Table 2 summarizes the frequency response characteristics of each configuration.
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
31
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
APPLICATION INFORMATION
output coupling capacitor, CC (continued)
Table 2. Common Load Impedances Vs Low Frequency Output Characteristics in SE Mode
RL
CC
LOWEST FREQUENCY
4Ω
330 µF
120 Hz
8Ω
330 µF
60 Hz
32 Ω
330 µF
15 Hz
47,000 Ω
330 µF
0.01 Hz
As Table 2 indicates, most of the bass response is attenuated into a 4-Ω load, an 8-Ω load is adequate,
headphone response is good, and drive into line level inputs (a home stereo for example) is exceptional.
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 relationship shown in equation 13.
ǒ
CB
1
25 kΩ
Ǔvǒ ǓƠ
1
CI RI
1
R LC C
(13)
mode control resistor network, RM1, RM2, RM3
Using a readily available 1/8-in. (3.5-mm) stereo headphone jack, the control switch is closed when no plug is
inserted. When closed, the 100-kΩ/1-kΩ divider (see Figure 64) pulls the MODE A input low. When a plug is
inserted, the 1-kΩ resistor is disconnected and the MODE A input is pulled high. When the input goes high, the
center BTL amplifier is shutdown causing the speaker to mute. The SE amplifiers then drive through the output
capacitors (CO) into the headphone jack.
Input MUX operation
The HP/LINE MUX feature gives the audio designer the flexibility of a multichip design in a single IC (see
Figure 64). The primary function of the MUX is to allow different gain settings for different types of audio loads.
Speakers typically require approximately a factor of 10 more gain for similar volume listening levels as
compared to headphones. To achieve headphone and speaker listening parity, the resistor values would need
to be set as follows:
Gain (HP)
+*
ǒ Ǔ
ǒ Ǔ
R F(HP)
(14)
R I(HP)
If, for example RI(HP) = 20 kΩ and RF(HP) = 20 kΩ then SE Gain(HP) = –1
Gain (LINE)
+*
R F(LINE)
(15)
R I(LINE)
If, for example RI(LINE) = 10 kΩ and RF(LINE) = 100 kΩ then Gain(LINE) = –10
32
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
TPA0103
1.75-W 3-CHANNEL STEREO AUDIO POWER AMPLIFIER
SLOS167A – JULY 1997 – REVISED MARCH 2000
APPLICATION INFORMATION
Input MUX operation (continued)
RFRHP
CIRLINE R
IRLINE
RFRLINE
21
RLINE IN
COUTR
–
+
MUX
20
CIRHP
RHP IN
Right Channel
ROUT 22
RIRHP
MID
VDD
MODE A 14
System
Control
16
HP/LINE
CNTL
MODE B 11
VDD
Left Channel
Figure 64. TPA0103 Example Input MUX Circuit
Another advantage of using the MUX feature is setting the gain of the headphone channel to –1. This provides
the optimum distortion performance into the headphones where clear sound is more important.
mute and shutdown modes
The TPA0103 employs both a mute and a shutdown mode of operation designed to reduce supply current, IDD,
to the absolute minimum level during periods of nonuse for battery-power conservation. 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 = 5 µA. SHUTDOWN should never
be left unconnected because amplifier operation would be unpredictable. Mute mode alone reduces IDD
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