ETC TPA6112A2DGQR

TPA6112A2
150-mW STEREO AUDIO POWER AMPLIFIER
SLOS342 – DECEMBER 2000
D
D
D
D
D
D
D
150 mW Stereo Output
Differential Inputs
PC Power Supply Compatible
– Fully Specified for 3.3 V and 5 V
Operation
– Operation to 2.5 V
Pop Reduction Circuitry
Internal Mid-Rail Generation
Thermal and Short-Circuit Protection
Surface-Mount Packaging
– PowerPAD MSOP
DGQ PACKAGE
(TOP VIEW)
VO 1
IN1–
IN1+
BYPASS
GND
1
10
2
9
3
8
4
7
5
6
VDD
VO 2
IN2–
IN2+
SHUTDOWN
description
The TPA6112A2 is a stereo audio power amplifier with differential inputs packaged in a 10-pin PowerPAD
MSOP package capable of delivering 150 mW of continuous RMS power per channel into 16-Ω loads. 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.
THD+N when driving an 16-Ω load from 5 V is 0.03% at 1 kHz, and less than 1% across the audio band of 20
Hz to 20 kHz. For 32-Ω loads, the THD+N is reduced to less than 0.02% at 1 kHz, and is less than 1% across
the audio band of 20 Hz to 20 kHz. For 10-kΩ loads, the THD+N performance is 0.005% at 1 kHz, and less than
0.5% across the audio band of 20 Hz to 20 kHz.
typical application circuit
325 kΩ
325 kΩ
VDD 10
VDD
C(S)
Ri
VDD/2
Ri
2
–
Right In
(Differential)
IN 1–
–
+
Ci
Ri
+
Ci
3
IN 1+
4
BYPASS
7
IN 2+
Rf
C(B)
Bias
Control
VO1 1
C(C)
SHUTDOWN 6
From
Shutdown
Control Circuit
Rf
Ri
+
Left In
(Differential)
Ci
Ri
8
–
Ci
IN 2–
+
VO2 9
–
5
C(C)
Rf
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.
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
TPA6112A2
150-mW STEREO AUDIO POWER AMPLIFIER
SLOS342 – DECEMBER 2000
AVAILABLE OPTIONS
PACKAGED DEVICE
MSOP†
TA
MSOP
Symbolization
– 40°C to 85°C
TPA6112A2DGQ
TI APD
† The DGQ package is available in left-ended tape and reel only (e.g.,
TPA6112A2DGQR).
Terminal Functions
TERMINAL
NAME
NO.
I/O
DESCRIPTION
BYPASS
4
I
Tap to voltage divider for internal mid-supply bias supply. Connect to a 0.1 µF to 1 µF low ESR capacitor for
best performance.
GND
5
I
GND is the ground connection.
IN1–
2
I
IN1– is the negative input for channel 1.
IN1+
3
I
IN1+ is the positive input for channel 1.
IN2–
8
I
IN2– is the negative input for channel 2.
IN2+
7
I
IN2+ is the positive input for channel 2.
SHUTDOWN
6
I
Puts the device in a low quiescent current mode when held high.
VDD
VO1
10
I
1
O
VDD is the supply voltage terminal.
VO1 is the audio output for channel 1.
VO2
9
O
VO2 is the audio output for channel 2.
absolute maximum ratings over operating free-air temperature (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
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
DGQ
2.14 W§
DERATING FACTOR
ABOVE TA = 25°C
TA = 70°C
POWER RATING
TA = 85°C
POWER RATING
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
Supply voltage, VDD
Operating free-air temperature, TA
High-level input voltage, VIH, (SHUTDOWN)
MAX
UNIT
2.5
5.5
V
–40
85
°C
60% x VDD
Low-level input voltage, VIL, (SHUTDOWN)
2
MIN
V
25% x VDD
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
V
TPA6112A2
150-mW STEREO AUDIO POWER AMPLIFIER
SLOS342 – DECEMBER 2000
dc electrical characteristics at TA = 25°C, VDD = 3.3 V
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
5
UNIT
VIO
PSRR
Input offset voltage
IDD
IDD(SD)
Supply current
1.5
3
mA
Supply current in SHUTDOWN mode
10
50
µA
Zi
Input impedance
>1
Power supply rejection ratio
VDD = 3.2 V to 3.4 V
83
mV
dB
MΩ
ac operating characteristics, VDD = 3.3 V, TA = 25°C, RL = 16 Ω
PARAMETER
TEST CONDITIONS
PO
THD+N
Output power (each channel)
THD ≤ 0.1%,
f = 1 kHz
Total harmonic distortion + noise
20 – 20 kHz
BOM
Maximum output power BW
PO = 40 mW,
G = 10,
Phase margin
Open loop
Supply ripple rejection ratio
f = 1 kHz
Channel/channel output separation
f = 1 kHz
SNR
Signal-to-noise ratio
Vn
Noise output voltage
PO = 50 mW,
AV = 1
MIN
TYP
MAX
60
UNIT
mW
0.4%
THD < 5%
> 20
kHz
96°
AV = 1
71
dB
89
dB
100
dB
µV(rms)
11
dc electrical characteristics at TA = 25°C, VDD = 5 V
PARAMETER
VIO
PSRR
Input offset voltage
IDD
IDD(SD)
Supply current
Zi
TEST CONDITIONS
MIN
TYP
MAX
UNIT
5
mV
1.5
3
mA
Supply current in SHUTDOWN mode
60
100
µA
Input impedance
>1
Power supply rejection ratio
VDD = 4.9 V to 5.1 V
76
dB
MΩ
ac operating characteristics, VDD = 5 V, TA = 25°C, RL = 16 Ω
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
PO
THD+N
Output power (each channel)
THD ≤ 0.1%,
Total harmonic distortion + noise
BOM
Maximum output power BW
PO = 100 mW, 20 – 20 kHz
G = 10,
THD < 5%
Phase margin
Open loop
Supply ripple rejection ratio
f = 1 kHz
61
dB
Channel/channel output separation
f = 1 kHz
90
dB
SNR
Signal-to-noise ratio
Vn
Noise output voltage
PO = 100 mW, AV = 1
AV = 1
POST OFFICE BOX 655303
f = 1 kHz
• DALLAS, TEXAS 75265
150
mW
0.6%
> 20
kHz
96°
100
dB
11.7
µV(rms)
3
TPA6112A2
150-mW STEREO AUDIO POWER AMPLIFIER
SLOS342 – DECEMBER 2000
ac operating characteristics, VDD = 3.3 V, TA = 25°C, RL = 32 Ω
PARAMETER
TEST CONDITIONS
PO
THD+N
Output power (each channel)
THD ≤ 0.1%,
f = 1 kHz
Total harmonic distortion + noise
20 – 20 kHz
BOM
Maximum output power BW
PO = 30 mW,
AV = 10,
Phase margin
Open loop
Supply ripple rejection ratio
f = 1 kHz
Channel/channel output separation
f = 1 kHz
SNR
Signal-to-noise ratio
Vn
Noise output voltage
PO = 40 mW,
AV = 1
MIN
TYP
MAX
40
UNIT
mW
0.4%
THD < 2%
> 20
kHz
96°
AV = 1
71
dB
95
dB
100
dB
µV(rms)
11
ac operating characteristics, VDD = 5 V, TA = 25°C, RL = 32 Ω
PARAMETER
TEST CONDITIONS
PO
THD+N
Output power (each channel)
THD ≤ 0.1%,
f = 1 kHz
Total harmonic distortion + noise
20 – 20 kHz
BOM
Maximum output power BW
PO = 60 mW,
AV = 10,
Phase margin
Open loop
Supply ripple rejection ratio
f = 1 kHz
Channel/channel output separation
f = 1 kHz
SNR
Signal-to-noise ratio
Vn
Noise output voltage
PO = 90 mW,
AV = 1
THD < 2%
MIN
TYP
90
MAX
UNIT
mW
0.4%
> 20
kHz
97°
AV = 1
61
dB
98
dB
100
dB
11.7
µV(rms)
TYPICAL CHARACTERISTICS
Table of Graphs
FIGURE
THD+N
vs Frequency
1, 3, 5, 6, 7, 9,
11, 13,
vs Output power
2, 4, 8, 10, 12,
14
Total harmonic distortion plus noise
Supply ripple rejection ratio
vs Frequency
15, 16
Output noise voltage
vs Frequency
17, 18
Crosstalk
vs Frequency
19 – 24
Shutdown attenuation
vs Frequency
25, 26
Open-loop gain and phase margin
vs Frequency
27, 28
Output power
vs Load resistance
29, 30,
IDD
Supply current
vs Supply voltage
31
SNR
Signal-to-noise ratio
vs Voltage gain
32
Power dissipation/amplifier
vs Load power
33, 34
Vn
4
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
TPA6112A2
150-mW STEREO AUDIO POWER AMPLIFIER
SLOS342 – DECEMBER 2000
TYPICAL CHARACTERISTICS
TOTAL HARMONIC DISTORTION + NOISE
vs
OUTPUT POWER
10
THD+N – Total Harmonic Distortion + Noise – %
THD+N – Total Harmonic Distortion + Noise – %
TOTAL HARMONIC DISTORTION + NOISE
vs
FREQUENCY
VDD = 3.3 V,
PO = 25 mW,
CB = 1 µF,
RL = 32 Ω,
AV = –1 V/V
1
0.1
0.01
0.001
20
100
1k
10
1
VDD = 3.3 V,
RL = 32 Ω,
AV = –1 V/V,
CB = 1 µF
20 kHz
0.1
1 kHz
0.01
0.001
10
10k 20k
50
Figure 1
Figure 2
1
AV = –5 V/V
AV = –1 V/V
AV = –10 V/V
0.1
0.05
0.01
0.001
20
100
1k
f – Frequency – Hz
TOTAL HARMONIC DISTORTION + NOISE
vs
OUTPUT POWER
THD+N – Total Harmonic Distortion + Noise – %
THD+N – Total Harmonic Distortion + Noise – %
TOTAL HARMONIC DISTORTION + NOISE
vs
FREQUENCY
VDD = 5 V,
PO = 60 mW,
CB = 1 µF,
RL = 32 Ω,
100
PO – Output Power – mW
f – Frequency – Hz
10
20 Hz
10k 20k
10
1
VDD = 5 V,
RL = 32 Ω,
AV = –1 V/V,
CB = 1 µF
20 Hz
20 kHz
0.1
1 kHz
0.01
0.001
10
100
500
PO – Output Power – mW
Figure 3
Figure 4
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• DALLAS, TEXAS 75265
5
TPA6112A2
150-mW STEREO AUDIO POWER AMPLIFIER
SLOS342 – DECEMBER 2000
TYPICAL CHARACTERISTICS
TOTAL HARMONIC DISTORTION + NOISE
vs
FREQUENCY
10
THD+N – Total Harmonic Distortion + Noise – %
THD+N – Total Harmonic Distortion + Noise – %
TOTAL HARMONIC DISTORTION + NOISE
vs
FREQUENCY
VDD = 3.3 V,
PO = 100 mW,
CB = 1 µF,
RL = 10 kΩ,
AV = –1 V/V
1
0.1
0.01
0.001
20
100
1k
f – Frequency – Hz
10
1
VDD = 5 V,
PO = 100 mW,
CB = 1 µF,
RL = 10 kΩ
AV = –5 V/V
AV = –1 V/V
0.1
AV = –10 V/V
0.01
0.001
20
10k 20k
100
Figure 5
THD+N – Total Harmonic Distortion + Noise – %
THD+N – Total Harmonic Distortion + Noise – %
TOTAL HARMONIC DISTORTION + NOISE
vs
OUTPUT POWER
10
VDD = 3.3 V,
PO = 60 mW,
CB = 1 µF,
RL = 8 Ω,
AV = –1 V/V
0.1
0.01
0.001
20
100
1k
f – Frequency – Hz
10k 20k
10
1
VDD = 3.3 V,
RL = 8 Ω,
AV = –1 V/V,
CB = 1 µF
20 Hz
20 kHz
0.1
1 kHz
0.01
0.001
10
100
PO – Output Power – mW
Figure 7
6
10k 20k
Figure 6
TOTAL HARMONIC DISTORTION + NOISE
vs
FREQUENCY
1
1k
f – Frequency – Hz
Figure 8
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
500
TPA6112A2
150-mW STEREO AUDIO POWER AMPLIFIER
SLOS342 – DECEMBER 2000
TYPICAL CHARACTERISTICS
TOTAL HARMONIC DISTORTION + NOISE
vs
OUTPUT POWER
10
VDD = 5 V,
PO = 150 mW,
CB = 1 µF,
RL = 8 kΩ
1
THD+N – Total Harmonic Distortion + Noise – %
THD+N – Total Harmonic Distortion + Noise – %
TOTAL HARMONIC DISTORTION + NOISE
vs
FREQUENCY
AV = –5 V/V
AV = –1 V/V
0.1
AV = –10 V/V
0.01
0.001
20
100
1k
f – Frequency – Hz
10
VDD = 5 V,
RL = 8 Ω,
AV = –1 V/V,
CB = 1 µF
1
0.01
20 Hz
100
PO – Output Power – mW
Figure 9
VDD = 3.3 V,
PO = 40 mW,
CB = 1 µF,
RL = 16 Ω,
AV = –1 V/V
0.1
0.01
100
TOTAL HARMONIC DISTORTION + NOISE
vs
OUTPUT POWER
THD+N – Total Harmonic Distortion + Noise – %
THD+N – Total Harmonic Distortion + Noise – %
10
0.001
20
1k
f – Frequency – Hz
500
Figure 10
TOTAL HARMONIC DISTORTION + NOISE
vs
FREQUENCY
1
20 kHz
0.1
0.001
10
10k 20k
1 kHz
10k 20k
10
1
VDD = 3.3 V,
RL =16 Ω,
AV = –1 V/V,
CB = 1 µF
20 Hz
20 kHz
1 kHz
0.1
0.01
0.001
10
Figure 11
100
PO – Output Power – mW
500
Figure 12
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• DALLAS, TEXAS 75265
7
TPA6112A2
150-mW STEREO AUDIO POWER AMPLIFIER
SLOS342 – DECEMBER 2000
TYPICAL CHARACTERISTICS
TOTAL HARMONIC DISTORTION + NOISE
vs
FREQUENCY
TOTAL HARMONIC DISTORTION + NOISE
vs
OUTPUT POWER
THD+N – Total Harmonic Distortion + Noise – %
THD+N – Total Harmonic Distortion + Noise – %
10
VDD = 5 V,
PO = 100 mW,
CB = 1 µF,
RL = 16 Ω
1
AV = –1 V/V
AV = –5 V/V
0.1
AV = –10 V/V
0.01
0.001
20
100
1k
f – Frequency – Hz
10k
10
1
VDD = 5 V,
RL = 16 Ω,
AV = –1 V/V,
CB = 1 µF
20 kHz
1 kHz
0.1
0.01
0.001
10
20k
Figure 14
SUPPLY RIPPLE REJECTION RATIO
vs
FREQUENCY
SUPPLY RIPPLE REJECTION RATIO
vs
FREQUENCY
VDD = 3.3 V,
RL = 16 Ω,
AV = –1 V/V
0.47 µF
–20
1 µF
–30
–40
–50
–60
–70
–80
Bypass = 1.65 V
–90
–100
–110
–120
20
100
1k
f – Frequency – Hz
10k 20k
0
K SVR – Supply Ripple Rejection Ratio – dB
K SVR – Supply Ripple Rejection Ratio – dB
0
0.1 µF
0.1 µF
–10
VDD = 5 V,
RL = 16 Ω,
AV = –1 V/V
0.47 µF
–20
1 µF
–30
–40
–50
–60
–70
–80
Bypass = 2.5 V
–90
–100
–110
–120
20
Figure 15
8
500
100
PO – Output Power – mW
Figure 13
–10
20 Hz
100
1k
f – Frequency – Hz
Figure 16
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• DALLAS, TEXAS 75265
10k
20k
TPA6112A2
150-mW STEREO AUDIO POWER AMPLIFIER
SLOS342 – DECEMBER 2000
TYPICAL CHARACTERISTICS
OUTPUT NOISE VOLTAGE
vs
FREQUENCY
OUTPUT NOISE VOLTAGE
vs
FREQUENCY
100
VDD = 3.3 V,
BW = 10 Hz to 22 kHz
RL = 16 Ω
AV = –10 V/V
AV = –1 V/V
10
V n – Output Noise Voltage – µ V(RMS)
V n – Output Noise Voltage – µ V(RMS)
100
1
20
100
1k
f – Frequency – Hz
AV = –10 V/V
AV = –1 V/V
10
VDD = 5 V,
BW = 10 Hz to 22 kHz
RL = 16 Ω,
1
10k 20k
20
100
Figure 17
1k
f – Frequency – Hz
Figure 18
CROSSTALK
vs
FREQUENCY
CROSSTALK
vs
FREQUENCY
0
–20
–30
–20
–30
–40
–50
–60
–70
–80
–40
–50
–60
–70
–80
IN2– to VO1
–90
IN2– to VO1
–90
–100
–100
–110
–120
VDD = 3.3 V,
PO = 40 mW,
CB = 1 µF,
RL = 16 Ω,
AV = –1 V/V
–10
Crosstalk – dB
Crosstalk – dB
0
VDD = 3.3 V,
PO = 25 mW,
CB = 1 µF,
RL = 32 Ω,
AV = –1 V/V
–10
10k 20k
IN1– to VO2
20
100
1k
f – Frequency – Hz
IN1– to VO2
–110
10k 20k
–120
20
Figure 19
100
1k
f – Frequency – Hz
10k 20k
Figure 20
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• DALLAS, TEXAS 75265
9
TPA6112A2
150-mW STEREO AUDIO POWER AMPLIFIER
SLOS342 – DECEMBER 2000
TYPICAL CHARACTERISTICS
CROSSTALK
vs
FREQUENCY
CROSSTALK
vs
FREQUENCY
0
0
VDD = 3.3 V,
PO = 60 mW,
CB = 1 µF,
RL = 8 Ω,
AV = –1 V/V
–10
–20
–20
–30
–40
Crosstalk – dB
Crosstalk – dB
–30
–50
–60
–70
IN2– to VO1
–80
–40
–50
–60
–70
–80
–90
IN2– to VO1
–90
–100
–100
IN1– to VO2
–110
–120
VDD = 5 V,
PO = 60 mW,
CB = 1 µF,
RL = 32 Ω,
AV = –1 V/V
–10
IN1– to VO2
–110
20
100
1k
f – Frequency – Hz
–120
10k 20k
20
100
Figure 21
CROSSTALK
vs
FREQUENCY
0
0
VDD = 5 V,
PO = 100 mW,
CB = 1 µF,
RL = 16 Ω,
AV = –1 V/V
–10
–20
–20
–30
–40
–50
–60
–70
–80
VDD = 5 V,
PO = 150 mW,
CB = 1 µF,
RL = 8 Ω,
AV = –1 V/V
–10
Crosstalk – dB
Crosstalk – dB
–30
–40
–50
–60
–70
IN2– to VO1
–80
IN2– to VO1
–90
–90
–100
–100
IN1– to VO2
–110
20
100
IN1– to VO2
–110
1k
f – Frequency – Hz
10k 20k
–120
20
Figure 23
10
10k 20k
Figure 22
CROSSTALK
vs
FREQUENCY
–120
1k
f – Frequency – Hz
100
1k
f – Frequency – Hz
Figure 24
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• DALLAS, TEXAS 75265
10k 20k
TPA6112A2
150-mW STEREO AUDIO POWER AMPLIFIER
SLOS342 – DECEMBER 2000
TYPICAL CHARACTERISTICS
SHUTDOWN ATTENUATION
vs
FREQUENCY
–10
–20
Shutdown Attenuation – dB
Shutdown Attenuation – dB
0
VDD = 3.3 V,
RL = 16 Ω,
CB = 1 µF
–10
–30
–40
–50
–60
–70
–20
–30
–40
–50
–60
–70
–80
–80
–90
–90
–100
10
100
1k
10 k
VDD = 5 V,
RL = 16 Ω,
CB = 1 µF
–100
10
1M
100
f – Frequency – Hz
Figure 25
VDD = 3.3 V
RL = 10 kΩ
180
120
150
100
Gain
120
Phase
90
30
Gain
0
40
–30
20
–60
–90
0
Open-Loop Gain – dB
60
60
VDD = 5 V
RL = 10 kΩ
90
60
60
30
Phase
0
40
–30
20
–60
–90
0
–120
–120
–20
–20
–150
–150
10 k
100 k
1M
–180
10 M
150
120
80
Φ m – Phase Margin – Deg
80
–40
1k
1M
OPEN-LOOP GAIN AND PHASE MARGIN
vs
FREQUENCY
180
120
Open-Loop Gain – dB
10 k
Figure 26
OPEN-LOOP GAIN AND PHASE MARGIN
vs
FREQUENCY
100
1k
f – Frequency – Hz
Φm – Phase Margin – Deg
0
SHUTDOWN ATTENUATION
vs
FREQUENCY
–40
1k
10 k
100 k
1M
–180
10 M
f – Frequency – Hz
f – Frequency – Hz
Figure 27
Figure 28
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• DALLAS, TEXAS 75265
11
TPA6112A2
150-mW STEREO AUDIO POWER AMPLIFIER
SLOS342 – DECEMBER 2000
TYPICAL CHARACTERISTICS
OUTPUT POWER
vs
LOAD RESISTANCE
OUTPUT POWER
vs
LOAD RESISTANCE
100
250
VDD = 3.3 V,
THD+N = 1%,
AV = –1 V/V
VDD = 5 V,
THD+N = 1%,
AV = –1 V/V
200
P – Output Power – mW
O
P – Output Power – mW
O
75
50
25
0
150
100
50
0
8 12 16 20 24 28 32 36 40 44 45 52 56 60 64
8 12 16 20 24 28 32 36 40 44 48 52 56 60 64
RL – Load Resistance – Ω
RL – Load Resistance – Ω
Figure 30
Figure 29
SUPPLY CURRENT
vs
SUPPLY VOLTAGE
SIGNAL-TO-NOISE RATIO
vs
VOLTAGE GAIN
2.5
120
SNR – Signal-to-Noise Ratio – dB
VDD = 5 V
I DD – Supply Current – mA
2
1.5
1
0.5
0
0
0.5
1
1.5 2 2.5 3 3.5 4 4.5
VDD – Supply Voltage – V
5
5.5
100
80
60
40
20
0
1
2
4
5
Figure 32
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6
7
AV – Voltage Gain – V/V
Figure 31
12
3
• DALLAS, TEXAS 75265
8
9
10
TPA6112A2
150-mW STEREO AUDIO POWER AMPLIFIER
SLOS342 – DECEMBER 2000
TYPICAL CHARACTERISTICS
POWER DISSIPATION/AMPLIFIER
vs
LOAD POWER
VDD = 3.3 V
Power Dissipation/Amplifier – mW
70
180
VDD = 5 V
8Ω
Power Dissipation/Amplifier – mW
80
60
50
40
16 Ω
30
32 Ω
20
64 Ω
10
POWER DISSIPATION/AMPLIFIER
vs
LOAD POWER
140
120
100
16 Ω
80
60
32 Ω
40
64 Ω
20
0
0
20
40
60
80 100 120 140 160 180
200
8Ω
160
0
0
20
40
Load Power – mW
60
80 100 120 140 160 180
200
Load Power – mW
Figure 33
Figure 34
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TPA6112A2
150-mW STEREO AUDIO POWER AMPLIFIER
SLOS342 – DECEMBER 2000
APPLICATION INFORMATION
gain setting resistors, Rf and Ri
The gain for the TPA6112A2 is set by resistors Rf and Ri according to equation 1.
Gain
+ RRf
(IN
i
)
– IN–)
(1)
Given that the TPA6112A2 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
+ RR)fRRi
f
(2)
i
As an example, consider an input resistance of 20 kΩ and a feedback resistor of 20 kΩ. The gain of the amplifier
would be – 1 and the effective impedance at the inverting terminal would be 10 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 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 20 kΩ and the specification calls for a flat bass response down to 20 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. It is important to confirm the capacitor polarity in the application.
14
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TPA6112A2
150-mW STEREO AUDIO POWER AMPLIFIER
SLOS342 – DECEMBER 2000
APPLICATION INFORMATION
power supply decoupling, C(S)
The TPA6112A2 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, C(B)
The midrail bypass capacitor, C(B), serves several important functions. During start up, C(B) 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 230-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
1
C (B)
230 kΩ
Ǔ
v ǒC1R Ǔ
(6)
i i
As an example, consider a circuit where C(B) is 1 µF, Ci is 1 µF, and RI is 20 kΩ. Inserting these values into the
equation 9 results in: 6.25 ≤ 50 which satisfies the rule. Bypass capacitor, C(B), 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, C(C)
In the typical single-supply single-ended (SE) configuration, an output coupling capacitor (C(C)) 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 typically small load impedances drive the
low-frequency corner higher. Large values of C(C) are required to pass low frequencies into the load. Consider
the example where a C(C) of 68 µF is chosen and loads vary from 32 Ω to 47 kΩ. Table 1 summarizes the
frequency response characteristics of each configuration.
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TPA6112A2
150-mW STEREO AUDIO POWER AMPLIFIER
SLOS342 – DECEMBER 2000
APPLICATION INFORMATION
Table 1. Common Load Impedances Vs Low Frequency Output Characteristics in SE Mode
RL
C(C)
68 µF
Lowest Frequency
32 Ω
10,000 Ω
68 µF
0.23 Hz
47,000 Ω
68 µF
0.05 Hz
73 Hz
As Table 1 indicates, 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. With the rules described earlier still valid, add the following
relationship:
ǒ
1
C (B)
230 kΩ
Ǔ
v ǒC1R Ǔ Ơ R C1
i i
(8)
L (C)
using low-ESR capacitors
Low-ESR capacitors are recommended throughout this application. 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.
5-V versus 3.3-V operation
The TPA6112A2 was designed for operation 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 since these 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 TPA6112A2 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.
16
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TPA6112A2
150-mW STEREO AUDIO POWER AMPLIFIER
SLOS342 – DECEMBER 2000
MECHANICAL DATA
DGQ (S-PDSO-G10)
PowerPAD PLASTIC SMALL-OUTLINE PACKAGE
0,27
0,17
0,50
10
0,25 M
6
Thermal Pad
(See Note D)
0,15 NOM
3,05
2,95
4,98
4,78
Gage Plane
0,25
1
0°– 6°
5
3,05
2,95
0,69
0,41
Seating Plane
1,07 MAX
0,15
0,05
0,10
4073273/A 04/98
NOTES: A.
B.
C.
D.
All linear dimensions are in millimeters.
This drawing is subject to change without notice.
Body dimensions do not include mold flash or protrusion.
The package thermal performance may be enhanced by bonding the thermal pad to an external thermal plane.
This pad is electrically and thermally connected to the backside of the die and possibly selected leads.
PowerPAD is a trademark of Texas Instruments.
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