TEXAS INSTRUMENTS TPA311 Technical data

TPA311

350-mW MONO AUDIO POWER AMPLIFIER

SLOS207C – JANUARY 1998 – REVISED MA Y 2003

D Fully Specified for 3.3-V and 5-V Operation D Wide Power Supply Compatibility

2.5 V – 5.5 V

D Output Power for R

– 350 mW at V – 250 mW at V – 250 mW at V – 75 mW at V

description

The TPA311 is a bridge-tied load (BTL) or single-ended (SE) audio power amplifier developed especially for low-voltage applications where internal speakers and external earphone operation are required. Operating with a 3.3-V

DD

= 8 Ω

L

= 5 V, BTL

DD

= 5 V, SE

DD

= 3.3 V, BTL

DD

= 3.3 V, SE

D Shutdown Control

– I

= 7 µA at 3.3 V

DD

– I

= 60 µA at 5 V

DD

D BTL to SE Mode Control D Integrated Depop Circuitry D Thermal and Short-Circuit Protection D Surface Mount Packaging

– SOIC – PowerPAD MSOP

D OR DGN PACKAGE

(TOP VIEW)

SHUTDOWN

BYPASS

SE/BTL

IN

1 2 3 4

V

8 7 6 5

O

GND V

DD

VO+

–

supply, the TPA311 can deliver 250-mW of continuous power into a BTL 8-Ω load at less than 1% THD+N throughout voice band frequencies. Although this device is characterized out to 20 kHz, its operation was optimized for narrower band applications such as cellular communications. The BTL configuration eliminates the need for external coupling capacitors on the output in most applications, which is particularly important for small battery-powered equipment. A unique feature of the TP A31 1 is that it allows the amplifier to switch from BTL to SE on the fly when an earphone drive is required. This eliminates complicated mechanical switching or auxiliary devices just to drive the external load. This device features a shutdown mode for power-sensitive applications with special depop circuitry to virtually eliminate speaker noise when exiting shutdown mode and during power cycling. The TP A31 1 is available in an 8-pin SOIC surface-mount package and the surface-mount PowerP AD MSOP, which reduces board space by 50% and height by 40%.

R

F

Audio

Input

From System Control

PowerPAD is a trademark of Texas Instruments.

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.

R

I

C

I

C

BF

From HP Jack

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.

IN

24BYPASS

SHUTDOWN

1 3

SE/BTL

Bias

Control

VDD/2

6

V

DD

C

S

VO+

–

+

–

+

Copyright  1998 – 2003, Texas Instruments Incorporated

5

VO–8

7

GND

C

350 mW

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

1

TPA311 350-mW MONO AUDIO POWER AMPLIFIER

SLOS207C – JANUARY 1998 – REVISED MAY 2003

AVAILABLE OPTIONS PACKAGED DEVICES

T

A

–40°C to 85°C TPA311D TPA311DGN AAB

†

The D and DGN packages are available taped and reeled. T o order a taped and reeled part, add the suffix R to the part number (e.g., TPA311DR).

SMALL OUTLINE

(D)

Terminal Functions

†

MSOP

(DGN)

†

MSOP

Symbolization

TERMINAL

NAME NO.

BYPASS 2 I GND 7 GND is the ground connection.

IN 4 I IN is the audio input terminal. SE/BTL 3 I SHUTDOWN 1 I SHUTDOWN places the entire device in shutdown mode when held high (IDD = 60 µA, VDD = 5 V).

V

DD

VO+ 5 O VO+ is the positive output for BTL and SE modes. VO– 8 O VO– is the negative output in BTL mode and a high-impedance output in SE mode.

I/O

BYPASS is the tap to the voltage divider for internal mid-supply bias. This terminal should be connected to a 0.1-µF to 1-µF capacitor when used as an audio amplifier.

When SE/BTL is held low, the TPA311 is in BTL mode. When SE/BTL is held high, the TPA311 is in SE mode.

6 VDD is the supply voltage terminal.

DESCRIPTION

absolute maximum ratings over operating free-air temperature range (unless otherwise noted)

Supply voltage, VDD 6 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Input voltage, V

Continuous total power dissipation internally limited (see Dissipation Rating Table). . . . . . . . . . . . . . . . . . . . .

Operating free-air temperature range, T Operating junction temperature range, T Storage temperature range, T

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.

–0.3 V to VDD +0.3 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

I

(see Table 3) –40°C to 85°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

A

–40°C to 150°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

–65°C to 150°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

stg

J

‡

DISSIPATION RATING TABLE

PACKAGE

D 725 mW 5.8 mW/°C 464 mW 377 mW

DGN 2.14 W

§

Please see the Texas Instruments document, PowerP AD 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 T exas Instruments Recommended Board for PowerPAD on page 33 of the before mentioned document.

2

TA ≤ 25°C DERATING FACTOR TA = 70°C TA = 85°C

§

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

17.1 mW/°C 1.37 W 1.11 W

TPA311

Á

БББББББББ

Á

БББББББББ

Á

БББББББББ

Á

БББББББББ

Á

БББББББББ

Á

БББББББББ

350-mW MONO AUDIO POWER AMPLIFIER

SLOS207C – JANUARY 1998 – REVISED MAY 2003

recommended operating conditions

MIN MAX UNIT

Supply voltage, V

High-level voltage, V

Low-level voltage, V

DD

IH

SE/BTL SHUTDOWN

SHUTDOWN

IL

SE/BTL

Operating free-air temperature, TA (see Table 3)

electrical characteristics at specified free-air temperature, VDD = 3.3 V , TA = 25°C (unless otherwise noted)

PARAMETER TEST CONDITIONS

|VOO|

PSRR

I

DD

Á

I

DD(SD)

Á

|IIH|

|IIL|

Output offset voltage (measured differentially)

Power supply rejection ratio

Supply current (see Figure 6)

ББББББББББ

Supply current, shutdown mode (see Figure 7)

ББББББББББ

High-level input current

Low-level input current

p

SHUTDOWN = 0 V, SE/BTL = 0 V, RL = 8 Ω, RF = 10 kΩ

VDD = 3.2 V to 3.4 V SHUTDOWN = 0 V,

SE/BTL

= 0.33 V, RF = 10 kΩ

SHUTDOWN = 0 V,

БББББББ

SE/BTL

= 2.97 V, RF = 10 kΩ

BTL mode SE mode

BTL mode

SE mode

ÁÁ

SHUTDOWN = VDD, SE/BTL = 0 V, RF = 10 kΩ

ББББББББББ

SHUTDOWN, VDD = 3.3 V, VI = V SE/BTL, VDD = 3.3 V, VI = V

DD

SHUTDOWN, VDD = 3.3 V, VI = 0 V SE/BTL, VDD = 3.3 V, VI = 0 V

0.9 V

2.5 DD DD

–40

0.1 V

5.5

DD DD

85

MIN TYP MAX UNIT

5

20

85 83

0.7

1.5

0.35

ÁÁÁ

0.75

Á

7

50

Á

1 1 1 1

mV

mA

Á

V

°C

dB

µA

operating characteristics, VDD = 3.3 V, T

= 25°C, R

A

= 8 Ω

L

PARAMETER TEST CONDITIONS

P

O

THD + N

ÁÁ

B

OM

B

1

ÁÁ

V

n

Output power, see Note 1 Total harmonic distortion plus

noise

БББББББ

Maximum output power bandwidth Unity-gain bandwidth

БББББББÁÁÁÁ

Supply ripple rejection ratio

БББББББ

Noise output voltage

THD = 0.5%, THD = 0.5%, PO = 250 mW,

See Figure 12

ÁÁÁ

AV = – 2 V/V, Open loop, f = 1 kHz,

See Figure 5 f = 1 kHz,

See Figure 3

ÁÁÁ

AV = – 1 V/V, BTL,

BTL mode, SE mode f = 20 Hz to 4 kHz,

ÁÁÁÁ

THD = 3%, See Figure 36 CB = 1 µF,

ÁÁÁÁ

CB = 1 µF,

ÁÁÁÁ

CB = 0.1 µF, See Figure 42

NOTE 1: Output power is measured at the output terminals of the device at f = 1 kHz.

See Figure 14

AV = – 2 V/V,

ÁÁÁ

See Figure 12

BTL mode,

ÁÁÁ

SE mode,

ÁÁÁ

RL = 32 Ω,

MIN TYP MAX UNIT

250 110

ÁÁÁ

1.3%

1.4

ÁÁÁ

10

71

ÁÁÁ

mW

kHz

MHz

86

ÁÁÁ

15

ÁÁÁ

µV(rms)

dB

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

3

TPA311

Á

350-mW MONO AUDIO POWER AMPLIFIER

SLOS207C – JANUARY 1998 – REVISED MAY 2003

electrical characteristics at specified free-air temperature, VDD = 5 V , TA = 25°C (unless otherwise noted)

PARAMETER TEST CONDITIONS

|VOO|

ÁÁ

PSRR

ÁÁÁББББББББББÁБББББББ

I

DD

ÁÁ

I

DD(SD)

|IIH|

|IIL|

Output offset voltage (measured differentially)

ББББББББББ

Power supply rejection ratio

Supply current (see Figure 6)

ББББББББББ

Supply current, shutdown mode (see Figure 7)

High-level input current

Low-level input current

p

SHUTDOWN = 0 V, SE/BTL = 0 V, RL = 8 Ω, RF = 10 kΩ

ББББББББББ

VDD = 4.9 V to 5.1 V SHUTDOWN = 0 V,

SE/BTL

= 0.5 V, RF = 10 kΩ

SHUTDOWN = 0 V, SE/BTL

= 4.5 V, RF = 10Ω

БББББББ

SHUTDOWN = VDD, SE/BTL = 0 V, RF = 10 kΩ,

SHUTDOWN, VDD = 5.5 V, VI = V SE/BTL, VDD = 5.5 V, VI = V SHUTDOWN, VDD = 5.5 V, VI = 0 V SE/BTL, VDD = 5.5 V, VI = 0 V

BTL mode SE mode

BTL mode

SE mode

DD

ÁÁ

DD

MIN TYP MAX UNIT

5

20

ÁÁÁ

78 76

ÁÁÁ

0.7

Á

1.5

Á

mV

Á

dB

Á

mA

0.35

60

0.75

Á

100

Á

µA

1

µA

1 1

µA

1

ÁÁÁ

operating characteristics, VDD = 5 V, T

= 25°C, R

A

= 8 Ω

L

PARAMETER TEST CONDITIONS

P

O

THD + N B

OM

B

1

Output power, see Note 2 Total harmonic distortion plus

noise Maximum output power bandwidth Unity-gain bandwidth

THD = 0.5%, THD = 0.5%, PO = 350 mW,

See Figure 16 AV = – 2 V/V, Open loop, f = 1 kHz,

ÁÁÁББББББББÁÁÁÁ

Supply ripple rejection ratio

See Figure 5 f = 1 kHz,

BTL mode, SE mode f = 20 Hz to 4 kHz,

THD = 2%, See Figure 37 CB = 1 µF,

ÁÁÁÁ

CB = 1 µF,

See Figure 4

V

n

ÁÁ

Noise output voltage

ББББББББ

AV = – 1 V/V, BTL,

ÁÁÁ

CB = 0.1 µF, See Figure 43

ÁÁÁÁ

NOTE 2: Output power is measured at the output terminals of the device at f = 1 kHz.

See Figure 18

AV = – 2 V/V,

See Figure 16

BTL mode,

ÁÁÁ

SE mode,

RL = 32 Ω,

ÁÁÁ

MIN TYP MAX UNIT

700 300

mW

1%

10

1.4

kHz

MHz

65

ÁÁÁ

dB

75

ÁÁÁ

15

µV(rms)

ÁÁÁ

4

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

Audio

Input

C

I

R

I

C

0.1 µF

TPA311

350-mW MONO AUDIO POWER AMPLIFIER

SLOS207C – JANUARY 1998 – REVISED MAY 2003

PARAMETER MEASUREMENT INFORMATION

6

V

DD

R

F

IN

24BYPASS

B

VDD/2

VO+

–

+

5

RL = 8

C

S

1 µF

V

DD

Ω

Audio

Input

C

I

0.1 µF

SHUTDOWN

1 3

SE/BTL

–

+

Bias

Control

VO– 8

7

GND

Figure 1. BTL Mode Test Circuit

6

V

DD

R

F

R

I

C

B

IN

24BYPASS

VDD/2

VO+

–

+

5

C

330 µF

C

S

1 µF

RL = 32

V

DD

Ω

–

+

SHUTDOWN

1 3

V

DD

SE/BTL

Bias

Control

VO– 8

7

GND

Figure 2. SE Mode Test Circuit

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

5

TPA311 350-mW MONO AUDIO POWER AMPLIFIER

SLOS207C – JANUARY 1998 – REVISED MAY 2003

TYPICAL CHARACTERISTICS

Table of Graphs

Supply voltage rejection ratio vs Frequency 3, 4, 5

I

DD

P

O

THD+N Total harmonic distortion plus noise

V

n

P

D

Supply current vs Supply voltage 6, 7

Output power

Open loop gain and phase vs Frequency 36, 37 Closed loop gain and phase vs Frequency 38, 39, 40, 41 Output noise voltage vs Frequency 42, 43 Power dissipation vs Output power 44, 45, 46, 47

FIGURE

vs Supply voltage 8, 9 vs Load resistance

vs Frequency

vs Output power

10, 11

12, 13, 16, 17, 20, 21, 24, 25, 28, 29,

32, 33

14, 15, 18, 19, 22, 23, 26, 27, 30, 31,

34, 35

SUPPLY VOLTAGE REJECTION RATIO

0

–10 –20

–30

–40

Supply Voltage Rejection Ratio – dB

–50

–60 –70

–80

–90

–100

CB = 1 µF

BYPASS = 1/2 V

20 100 1 k

vs

FREQUENCY

CB = 0.1 µF

DD

f – Frequency – Hz

Figure 3

VDD = 3.3 V RL = 8 Ω SE

10 k 20 k

SUPPLY VOLTAGE REJECTION RATIO

0

–10 –20

–30

–40 –50

–60 –70

–80

Supply Voltage Rejection Ratio – dB

–90

–100

CB = 1 µF

BYPASS = 1/2 V

20 100 1 k

vs

FREQUENCY

VDD = 5 V RL = 8 Ω SE

CB = 0.1 µF

DD

10 k 20 k

f – Frequency – Hz

Figure 4

6

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

350-mW MONO AUDIO POWER AMPLIFIER

TYPICAL CHARACTERISTICS

TPA311

SLOS207C – JANUARY 1998 – REVISED MAY 2003

SUPPLY VOLTAGE REJECTION RATIO

0

RL = 8 Ω

–10

CB = 1 µF BTL

–20

–30

–40 –50

–60 –70

–80

Supply Voltage Rejection Ratio – dB

–90

–100

20 100 1 k

vs

FREQUENCY

VDD = 5 V

VDD = 3.3 V

f – Frequency – Hz

Figure 5

90

80

70

1.1

0.9

0.7

0.5

0.3

– Supply Current – mA

DD

I

0.1

10 k 20 k

–0.1

SUPPLY CURRENT (SHUTDOWN)

vs

SUPPLY VOLTAGE

SHUTDOWN = V SE/BTL

= 0 V

RF = 10 kΩ

DD

SUPPLY CURRENT

SUPPLY VOLTAGE

SHUTDOWN = 0 V RF = 10 kΩ

34 62 5

VDD – Supply Voltage – V

Figure 6

vs

SE/BTL = 0.1 V

SE/BTL = 0.9 V

DD

– Supply Current – Aµ

DD(SD)

I

60

50

40

30

20 10

0

25

343.5 4.5

VDD – Supply Voltage – V

5.52.5

Figure 7

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

7

TPA311 350-mW MONO AUDIO POWER AMPLIFIER

SLOS207C – JANUARY 1998 – REVISED MAY 2003

TYPICAL CHARACTERISTICS

– Output Power – mW

O

P

1000

800

600

400

200

800

700

OUTPUT POWER

vs

SUPPLY VOLTAGE

THD+N 1% BTL

RL = 8 Ω

RL = 32 Ω

0

2.5 3.53 4 5.5

2

VDD – Supply Voltage – V

4.5 5

Figure 8

OUTPUT POWER

vs

LOAD RESISTANCE

THD+N = 1% BTL

– Output Power – mW

O

P

350

300

250

200

150

100

50

350

300

0

2

THD+N 1% SE

OUTPUT POWER

vs

SUPPLY VOLTAGE

RL = 8 Ω

RL = 32 Ω

343.5 4.5

VDD – Supply Voltage – V

Figure 9

OUTPUT POWER

vs

LOAD RESISTANCE

THD+N = 1% SE

5

5.52.5

600

VDD = 5 V

500

400

– Output Power – mW

O

P

300

200

100

VDD = 3.3 V

0

16 3224 40 64

8

RL – Load Resistance – Ω

48 56

Figure 10

8

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

– Output Power – mW

O

P

250

200

150

100

50

VDD = 5 V

VDD = 3.3 V

0

14 2620 32 5083844

RL – Load Resistance – Ω

56 62

Figure 11

350-mW MONO AUDIO POWER AMPLIFIER

TYPICAL CHARACTERISTICS

TPA311

SLOS207C – JANUARY 1998 – REVISED MAY 2003

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

FREQUENCY

10

VDD = 3.3 V PO = 250 mW RL = 8 Ω BTL

1

AV = –10 V/V

0.1

THD+N –Total Harmonic Distortion + Noise – %

0.01 20 1k 10k

AV = –20 V/V

AV = –2 V/V

f – Frequency – Hz

Figure 12

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

OUTPUT POWER

10

VDD = 3.3 V f = 1 kHz AV = –2 V/V BTL

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

FREQUENCY

10

VDD = 3.3 V RL = 8 Ω AV = –2 V/V BTL

1

0.1

THD+N –Total Harmonic Distortion + Noise – %

20k100

0.01 20 1k 10k

PO = 250 mW

f – Frequency – Hz

PO = 50 mW

PO = 125 mW

20k100

Figure 13

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

OUTPUT POWER

10

f = 20 kHz

f = 10 kHz

1

RL = 8 Ω

0.1

THD+N –Total Harmonic Distortion + Noise – %

0.01

0.04 0.1 0.4

0.16 0.22 0.28 0.34

PO – Output Power – W

Figure 14

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

1

f = 1 kHz

0.1 f = 20 Hz

THD+N –Total Harmonic Distortion + Noise – %

0.01

0.01 0.1 1 PO – Output Power – W

VDD = 3.3 V RL = 8 Ω AV = –2 V/V BTL

Figure 15

9

TPA311 350-mW MONO AUDIO POWER AMPLIFIER

SLOS207C – JANUARY 1998 – REVISED MAY 2003

TYPICAL CHARACTERISTICS

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

FREQUENCY

10

VDD = 5 V PO = 350 mW RL = 8 Ω BTL

1

AV = –10 V/V

0.1

THD+N –Total Harmonic Distortion + Noise – %

0.01 20 1k 10k

AV = –20 V/V

AV = –2 V/V

f – Frequency – Hz

Figure 16

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

OUTPUT POWER

10

VDD = 5 V f = 1 kHz AV = –2 V/V BTL

1

RL = 8 Ω

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

FREQUENCY

10

VDD = 5 V RL = 8 Ω AV = –2 V/V BTL

1

0.1

THD+N –Total Harmonic Distortion + Noise – %

20k100

0.01 20 1k 10k

PO = 350 mW

f – Frequency – Hz

PO = 50 mW

PO = 175 mW

20k100

Figure 17

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

OUTPUT POWER

10

f = 20 kHz

f = 10 kHz

1

f = 1 kHz

10

0.1

THD+N –Total Harmonic Distortion + Noise – %

0.01

0.1 0.25 10.40 0.55 0.70 0.85 PO – Output Power – W

Figure 18

0.1

VDD = 5 V RL = 8 Ω AV = –2 V/V

THD+N –Total Harmonic Distortion + Noise – %

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

BTL

0.01

0.01 0.1 1

f = 20 Hz

PO – Output Power – W

Figure 19

350-mW MONO AUDIO POWER AMPLIFIER

TYPICAL CHARACTERISTICS

TPA311

SLOS207C – JANUARY 1998 – REVISED MAY 2003

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

FREQUENCY

10

VDD = 3.3 V PO = 30 mW RL = 32 Ω SE

1

0.1 AV = –1 V/V

AV = –10 V/V

0.01 AV = –5 V/V

THD+N –Total Harmonic Distortion + Noise – %

0.001 20 1k 10k

f – Frequency – Hz

Figure 20

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

OUTPUT POWER

10

VDD = 3.3 V f = 1 kHz RL = 32 Ω AV = –1 V/V SE

1

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

FREQUENCY

10

VDD = 3.3 V RL = 32 Ω AV = –1 V/V SE

1

PO = 10 mW

0.1

0.01 PO = 15 mW

THD+N –Total Harmonic Distortion + Noise – %

20k100

0.001

PO = 30 mW

20 1k 10k

f – Frequency – Hz

20k100

Figure 21

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

OUTPUT POWER

10

1

f = 20 kHz

f = 10 kHz

VDD = 3.3 V RL = 32 Ω AV = –1 V/V SE

0.1

THD+N –Total Harmonic Distortion + Noise – %

0.01

0.02 0.025 0.050.03 0.035 0.04 0.045 PO – Output Power – W

Figure 22

0.1

f = 20 Hz

THD+N –Total Harmonic Distortion + Noise – %

0.01

0.002 0.03 0.050.01

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

f = 1 kHz

0.02

PO – Output Power – W

Figure 23

11

TPA311 350-mW MONO AUDIO POWER AMPLIFIER

SLOS207C – JANUARY 1998 – REVISED MAY 2003

TYPICAL CHARACTERISTICS

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

FREQUENCY

10

VDD = 5 V PO = 60 mW RL = 32 Ω SE

1

AV = –10 V/V

0.1

AV = –5 V/V

0.01

THD+N –Total Harmonic Distortion + Noise – %

0.001 20 1k 10k

AV = –1 V/V

f – Frequency – Hz

Figure 24

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

OUTPUT POWER

10

VDD = 5 V f = 1 kHz RL = 32 Ω AV = –1 V/V SE

1

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

FREQUENCY

10

VDD = 5 V RL = 32 Ω AV = –1 V/V SE

1

PO = 15 mW

0.1

PO = 30 mW

0.01

PO = 60 mW

THD+N –Total Harmonic Distortion + Noise – %

20k100

0.001 20 1k 10k

f – Frequency – Hz

20k100

Figure 25

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

OUTPUT POWER

10

f = 20 kHz

1

f = 10 kHz

12

0.1

THD+N –Total Harmonic Distortion + Noise – %

0.01

0.02 0.04 0.140.06 0.08 0.1 0.12 PO – Output Power – W

Figure 26

0.1

THD+N –Total Harmonic Distortion + Noise – %

0.01

0.002 0.1 0.20.01

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

f = 1 kHz

f = 20 Hz

VDD = 5 V RL = 32 Ω AV = –1 V/V SE

PO – Output Power – W

Figure 27

350-mW MONO AUDIO POWER AMPLIFIER

TYPICAL CHARACTERISTICS

TPA311

SLOS207C – JANUARY 1998 – REVISED MAY 2003

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

FREQUENCY

1

VDD = 3.3 V PO = 0.1 mW RL = 10 kΩ SE

0.1 AV = –1 V/V

AV = –2 V/V

AV = –5 V/V

THD+N –Total Harmonic Distortion + Noise – %

0.01 20 1k 10k

f – Frequency – Hz

Figure 28

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

OUTPUT POWER

10

VDD = 3.3 V f = 1 kHz RL = 10 kΩ AV = –1 V/V

1

SE

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

FREQUENCY

1

VDD = 3.3 V RL = 10 kΩ AV = –1 V/V SE

PO = 0.05 mW

0.1

THD+N –Total Harmonic Distortion + Noise – %

20k100

0.01 20 1 k 10 k

f – Frequency – Hz

PO = 0.13 mW

PO = 0.1 mW

20 k100

Figure 29

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

OUTPUT POWER

10

VDD = 3.3 V RL = 10 kΩ AV = –1 V/V SE

1

0.1

0.01

THD+N –Total Harmonic Distortion + Noise – %

0.001 50 75 200100 125 150 175

PO – Output Power – µW

Figure 30

0.1

0.01

THD+N –Total Harmonic Distortion + Noise – %

0.001 5 100 500

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

f = 20 Hz

10

f = 20 kHz

f = 10 kHz

PO – Output Power – µW

Figure 31

f = 1 kHz

13

TPA311 350-mW MONO AUDIO POWER AMPLIFIER

SLOS207C – JANUARY 1998 – REVISED MAY 2003

TYPICAL CHARACTERISTICS

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

FREQUENCY

1

VDD = 5 V PO = 0.3 mW RL = 10 kΩ SE

0.1

AV = –1 V/V

AV = –2 V/V

THD+N –Total Harmonic Distortion + Noise – %

0.01 20 1k 10k

AV = –5 V/V

f – Frequency – Hz

Figure 32

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

OUTPUT POWER

10

VDD = 5 V f = 1 kHz RL = 10 kΩ AV = –1 V/V

1

SE

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

FREQUENCY

1

VDD = 5 V RL = 10 kΩ AV = –1 V/V SE

PO = 0.3 mW

0.1

THD+N –Total Harmonic Distortion + Noise – %

20k100

0.01 20 1k 10k

f – Frequency – Hz

PO = 0.2 mW

PO = 0.1 mW

20k100

Figure 33

TOTAL HARMONIC DISTORTION PLUS NOISE

vs

OUTPUT POWER

10

VDD = 5 V RL = 10 kΩ AV = –1 V/V SE

1

14

0.1

0.01

THD+N –Total Harmonic Distortion + Noise – %

0.001 50 125 500200 275 350 425

PO – Output Power – µW

Figure 34

0.1

0.01

THD+N –Total Harmonic Distortion + Noise – %

0.001 5 100 500

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

f = 20 kHz

f = 20 Hz

f = 1 kHz

f = 10 kHz

10

PO – Output Power – µW

Figure 35

40

30

20

10

TPA311

350-mW MONO AUDIO POWER AMPLIFIER

SLOS207C – JANUARY 1998 – REVISED MAY 2003

TYPICAL CHARACTERISTICS

OPEN-LOOP GAIN AND PHASE

vs

FREQUENCY

Phase

Gain

0

VDD = 3.3 V RL = Open BTL

180

120

60

°

0

Phase –

Open-Loop Gain – dB

–10

–20

–30

40

30

20

10

–10

–60

–120

1

10

f – Frequency – kHz

10

2

10

3

10

4

–180

Figure 36

OPEN-LOOP GAIN AND PHASE

vs

FREQUENCY

Phase

Gain

0

VDD = 5 V RL = Open BTL

180

120

60

°

0

Phase –

–60

–20

–30

1

10

f – Frequency – kHz

10

2

Figure 37

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

10

–120

3

10

4

–180

15

TPA311 350-mW MONO AUDIO POWER AMPLIFIER

SLOS207C – JANUARY 1998 – REVISED MAY 2003

TYPICAL CHARACTERISTICS

CLOSED-LOOP GAIN AND PHASE

FREQUENCY

Closed-Loop Gain – dB

0.75

0.5

0.25

–0.25

–0.5

–0.75

–1

–1.25

–1.5

–1.75

–2

1

0

VDD = 3.3 V RL = 8 Ω PO = 0.25 W CI =1 µF BTL

1

10

Phase

Gain

2

10

f – Frequency – Hz

vs

180

170

160

°

150

Phase –

140

130

3

10

4

10

5

10

6

120

Closed-Loop Gain – dB

0.75

0.5

0.25

–0.25

–0.5

–0.75

–1

–1.25

–1.5

–1.75

–2

Figure 38

CLOSED-LOOP GAIN AND PHASE

vs

FREQUENCY

1

0

VDD = 5 V RL = 8 Ω PO = 0.35 W CI =1 µF BTL

1

10

Phase

Gain

2

3

10

f – Frequency – Hz

Figure 39

10

180

170

160

°

150

Phase –

140

130

4

10

5

10

6

120

16

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Closed-Loop Gain – dB

–1

–2 –3

7

6 5 4

3

2

1

0

1

10

350-mW MONO AUDIO POWER AMPLIFIER

TYPICAL CHARACTERISTICS

CLOSED-LOOP GAIN AND PHASE

vs

FREQUENCY

Phase

Gain

VDD = 3.3 V RL = 32 Ω AV = –2 V/V PO = 30 mW CI =1 µF CC =470 µF SE

10

2

3

10

f – Frequency – Hz

10

4

10

SLOS207C – JANUARY 1998 – REVISED MAY 2003

180

170

160

150

°

140

Phase –

130

120

110

10

100

6

5

TPA311

Closed-Loop Gain – dB

–1

–2

7

6

5

4

3

2

1

0

1

10

Figure 40

CLOSED-LOOP GAIN AND PHASE

vs

FREQUENCY

Phase

Gain

VDD = 5 V RL = 32 Ω AV = –2 V/V PO = 60 mW CI =1 µF CC =470 µF SE

10

2

3

10

f – Frequency – Hz

10

4

Figure 41

10

180

170

160

150

°

140

Phase –

130

120

110

10

100

6

5

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17

TPA311 350-mW MONO AUDIO POWER AMPLIFIER

SLOS207C – JANUARY 1998 – REVISED MAY 2003

TYPICAL CHARACTERISTICS

OUTPUT NOISE VOLTAGE

vs

FREQUENCY

100

VDD = 3.3 V BW = 22 Hz to 22 kHz RL = 32 Ω

V(rms)

– Output Noise Voltage –µV

n

CB =0.1 µF AV = –1 V/V

VO BTL

10

V

1

20 1 k 10 k

f – Frequency – Hz

Figure 42

POWER DISSIPATION

vs

OUTPUT POWER

300

O+

OUTPUT NOISE VOLTAGE

vs

FREQUENCY

100

VDD = 5 V BW = 22 Hz to 22 kHz RL = 32 Ω

V(rms)

– Output Noise Voltage –µV

n

20 k100

CB =0.1 µF AV = –1 V/V

VO BTL

10

1

20 1 k 10 k

V

O+

f – Frequency – Hz

20 k100

Figure 43

POWER DISSIPATION

vs

OUTPUT POWER

80

– Power Dissipation – mW

D

P

270

240

210

180

150

120

90

VDD = 3.3 V RL = 8 Ω BTL

100 300

PO – Output Power – mW

200 4000

Figure 44

– Power Dissipation – mW

D

P

72

64 56

48

40

32

24

16

RL = 8 Ω

RL = 32 Ω

8 0

30 90

PO – Output Power – mW

60 1200

VDD = 3.3 V SE

Figure 45

18

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350-mW MONO AUDIO POWER AMPLIFIER

TYPICAL CHARACTERISTICS

TPA311

SLOS207C – JANUARY 1998 – REVISED MAY 2003

– Power Dissipation – mW

D

P

720

640

560

480

400

320

240

160

POWER DISSIPATION

vs

OUTPUT POWER

VDD = 5 V RL = 8 Ω BTL

200 600400 8000 1000 1200

PO – Output Power – mW

Figure 46

– Power Dissipation – mW

D

P

180

160

140

120

100

80

60

40

POWER DISSIPATION

vs

OUTPUT POWER

RL = 8 Ω

RL = 32 Ω

VDD = 5 V SE

50 150100 2000 250 300

PO – Output Power – mW

Figure 47

APPLICATION INFORMATION

bridge-tied load versus single-ended mode

Figure 48 shows a linear audio power amplifier (AP A) in a BTL configuration. The TPA31 1 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 × V squared, yields 4× the output power from the same supply rail and load impedance (see equation 1).

V

(rms)

Power +

+

O(PP)

22

V

(rms)

R

Ǹ

2

L

into the power equation, where voltage is

O(PP)

(1)

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19

TPA311 350-mW MONO AUDIO POWER AMPLIFIER

SLOS207C – JANUARY 1998 – REVISED MAY 2003

APPLICATION INFORMATION

bridge-tied load versus single-ended mode (continued)

V

DD

V

O(PP)

R

V

DD

L

2x V

–V

O(PP)

Figure 48. Bridge-Tied Load Configuration

In typical portable handheld equipment, a sound channel operating at 3.3 V and using bridging raises the power into an 8-Ω speaker from a single-ended (SE, ground reference) limit of 62.5 mW to 250 mW. In terms of sound power that is a 6-dB improvement, which is loudness that can be heard. In addition to increased power there are frequency response concerns. Consider the single-supply SE configuration shown in Figure 49. 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), tend to be expensive, heavy, and occupy valuable PCB area. These capacitors also 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.

2p R

1

C

L

C

f

+

c

(2)

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.

20

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350-mW MONO AUDIO POWER AMPLIFIER

APPLICATION INFORMATION

bridge-tied load versus single-ended mode (continued)

V

DD

TPA311

SLOS207C – JANUARY 1998 – REVISED MAY 2003

V

O(PP)

C

R

L

V

O(PP)

–3 dB

f

c

Figure 49. Single-Ended Configuration and Frequency Response

Increasing power to the load does carry a penalty of increased internal power dissipation. The increased dissipation is understandable, considering that the BTL configuration produces 4× the output power of the SE configuration. Internal dissipation versus output power is discussed further in the thermal considerations section.

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 V The internal voltage drop multiplied by the RMS value of the supply current, I power dissipation of the amplifier.

rms, determines the internal

DD

.

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 50).

I

DD

I

DD(RMS)

V

(LRMS)

V

O

Figure 50. Voltage and Current Waveforms for BTL Amplifiers

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21

TPA311 350-mW MONO AUDIO POWER AMPLIFIER

SLOS207C – JANUARY 1998 – REVISED MAY 2003

APPLICATION INFORMATION

BTL amplifier efficiency (continued)

Although the voltages and currents for SE and BTL are sinusoidal in the load, currents from the supply are very different between SE and BTL configurations. In an SE application the current waveform is a half-wave rectified shape whereas, in BTL it is a full-wave rectified waveform. This means RMS conversion factors are different. Keep in mind that for most of the waveform, both the push and pull transistors are not on at the same time, which supports the fact that each amplifier in the BTL device only draws current from the supply for half the waveform. The following equations are the basis for calculating amplifier efficiency.

P

V

L

V

P

Ǹ

2

2V

p R

P

rms

R

P

L

SUP

L

+

V

2R

2

p

L

V

DD2VP

p R

L

2

where

Efficiency +

+

P

L

VLrms +

I

P

DD

+ VDDIDDrms +

SUP

rms +

(3)

Efficiency of a BTL Configuration +

p V

2V

DD

PLR

ǒ

p

P

+

2V

1ń2

L

Ǔ

2

DD

(4)

T able 1 employs equation 4 to calculate efficiencies for three dif ferent output power levels. 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. 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.

Table 1. Efficiency Vs Output Power in 3.3-V 8-Ω BTL Systems

OUTPUT POWER

(W)

0.125 33.6 1.41 0.26

0.25 47.6 2.00 0.29

0.375 58.3 2.45

†

High-peak voltage values cause the THD to increase.

EFFICIENCY

(%)

PEAK-TO-PEAK

VOLTAGE

(V)

†

INTERNAL

DISSIPATION

(W)

0.28

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. In equation 4, V that as V

goes down, efficiency goes up.

DD

is in the denominator. This indicates

DD

22

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350-mW MONO AUDIO POWER AMPLIFIER

SLOS207C – JANUARY 1998 – REVISED MAY 2003

APPLICATION INFORMATION

application schematic

Figure 51 is a schematic diagram of a typical handheld audio application circuit, configured for a gain of –10 V/V.

TPA311

C

I

0.47 µF

2.2 µF

R

F

50 kΩ

R

I

10 kΩ

C

B

100 kΩ

C

F

5 pF

Audio

Input

From System Control

0.1 µF

V

DD

IN

24BYPASS

SHUTDOWN

1 3

SE/BTL

V

DD

VDD/2

–

+

–

+

Bias

Control

VO+

VO– 8

GND

Figure 51. TPA311 Application Circuit

6

C

5

7

330 µF

1 kΩ

C

S

1 µF

V

DD

The following sections discuss the selection of the components used in Figure 51.

component selection

gain setting resistors, RF and R

The gain for each audio input of the TP A31 1 is set by resistors RF and RI according to equation 5 for BTL mode.

BTL Gain + A

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 TPA311 is a MOS amplifier, the input impedance is very high, consequently input leakage currents are not generally a concern, although noise in the circuit increases as the value of R

increases. In addition, a certain range of RF values is required for proper start-up operation of the

F

amplifier. Taken together it is recommended that the effective impedance seen by the inverting node of the amplifier be set between 5 kΩ and 20 kΩ. The effective impedance is calculated in equation 6.

Effective Impedance +

+*2

V

I

R

F

ǒ

Ǔ

R

I

R

FRI

RF) R

I

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(5)

(6)

23

TPA311 350-mW MONO AUDIO POWER AMPLIFIER

SLOS207C – JANUARY 1998 – REVISED MAY 2003

APPLICATION INFORMATION

component selection (continued)

As an example consider an input resistance of 10 kΩ and a feedback resistor of 50 kΩ. The BTL gain of the amplifier would be –10 V/V and the effective impedance at the inverting terminal would be 8.3 kΩ, which is well within the recommended range.

For high performance applications, metal film resistors are recommended because they tend to have lower noise levels than carbon resistors. For values of R to a pole formed from R compensation capacitor, C

and the inherent input capacitance of the MOS input structure. For this reason, a small

F

, of approximately 5 pF should be placed in parallel with RF when RF is greater than

F

50 kΩ. This, in effect, creates a low pass filter network with the cutoff frequency defined in equation 7.

–3 dB

above 50 kΩ the amplifier tends to become unstable due

F

f

c(lowpass)

+

2p R

1

FCF

f

c

For example, if RF is 100 kΩ and CF is 5 pF then fc is 318 kHz, which is well outside the audio range.

input capacitor, C

I

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, C

and RI form a high-pass filter with the corner frequency

I

determined in equation 8.

–3 dB

f

c(highpass)

+

2p R

1

C

I

(7)

(8)

f

c

The value of CI is important to consider as it directly affects the bass (low frequency) performance of the circuit. Consider the example where R

is 10 kΩ and the specification calls for a flat bass response down to 40 Hz.

I

Equation 8 is reconfigured as equation 9.

+

2p R

1

f

c

I

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24

C

I

(9)

350-mW MONO AUDIO POWER AMPLIFIER

SLOS207C – JANUARY 1998 – REVISED MAY 2003

APPLICATION INFORMATION

component selection (continued)

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 (R the feedback resistor (R that reduces useful headroom, especially in high gain applications. For this reason a low-leakage tantalum or ceramic capacitor is the best choice. When polarized capacitors are used, the positive side of the capacitor should face the amplifier input in most applications as the dc level there is held at V than the source dc level. It is important to confirm the capacitor polarity in the application.

) to the load. This leakage current creates a dc offset voltage at the input to the amplifier

F

/2, which is likely higher

DD

TPA311

, CI) and

I

power supply decoupling, C

The TP A311 is a high-performance CMOS audio amplifier that requires adequate power supply decoupling to ensure the output total harmonic distortion (THD) is as low as possible. Power supply decoupling also prevents oscillations for long lead lengths between the amplifier and the speaker. The optimum decoupling is achieved by using two capacitors of different types that target different types of noise on the power supply leads. For higher frequency transients, spikes, or digital hash on the line, a good low equivalent-series-resistance (ESR) ceramic capacitor, typically 0.1 µF placed as close as possible to the device V lower-frequency noise signals, a larger aluminum electrolytic capacitor of 10 µF or greater placed near the audio power amplifier is recommended.

midrail bypass capacitor, C

The midrail bypass capacitor, CB, is the most critical capacitor and serves several important functions. During start-up or recovery from shutdown mode, C function is to reduce noise produced by the power supply caused by coupling into the output drive signal. This noise is from the midrail generation circuit internal to the amplifier, which appears as degraded PSRR and THD + N. The capacitor is fed from a 250-kΩ source inside the amplifier. To keep the start-up pop as low as possible, the relationship shown in equation 10 should be maintained, which insures the input capacitor is fully charged before the bypass capacitor is fuly charged and the amplifier starts up.

10

ǒ

CB 250 kΩ

As an example, consider a circuit where CB is 2.2 µF, CI is 0.47 µF, RF is 50 kΩ and RI is 10 kΩ. Inserting these values into the equation 10 we get: 18.2 ≤ 35.5 which satisfies the rule. Bypass capacitor, C to 2.2 µF ceramic or tantalum low-ESR capacitors are recommended for the best THD and noise performance.

Ǔ

B

v

S

ǒ

RF) R

lead, works best. For filtering

DD

determines the rate at which the amplifier starts up. The second

B

1

Ǔ

C

I

, values of 0.1 µF

B

(10)

single-ended operation

In SE mode (see Figure 51), the load is driven from the primary amplifier output (VO+, terminal 5). In SE mode the gain is set by the R

is not used to mirror the voltage swing on the load, the factor of 2, from equation 5, is not included.

SE Gain + A

+*

V

and RI resistors and is shown in equation 1 1. Since the inverting amplifier

F

R

F

ǒ

Ǔ

R

I

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(11)

25

TPA311 350-mW MONO AUDIO POWER AMPLIFIER

SLOS207C – JANUARY 1998 – REVISED MAY 2003

APPLICATION INFORMATION

single-ended operation (continued)

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:

10

ǒ

CB 250 kΩ

v

Ǔ

ǒ

RF) R

1

Ǔ

C

I

1

Ơ

RLC

I

C

As an example, consider a circuit where CB is 0.2.2 µF, CI is 0.47 µF, CC is 330 µF, RF is 50 kΩRL is 32 Ω, and R

is 10 kΩ. Inserting these values into the equation 12 we get:

I

18.2 t 35.5 Ơ 94.7 which satisfies the rule.

output coupling capacitor, C

In the typical single-supply SE configuration, an output coupling capacitor (C

C

) is required to block the dc bias

C

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 13.

–3 dB

f

c(high pass)

+

2p R

1

C

L

f

c

(12)

(13)

The main disadvantage, from a performance standpoint, is that the typically small load impedances drive the low-frequency corner higher degrading the bass response. Large values of C frequencies into the load. Consider the example where a C

of 330 µF is chosen and loads vary from 8 Ω,

C

are required to pass low

C

32 Ω, to 47 kΩ. Table 2 summarizes the frequency response characteristics of each configuration.

Table 2. Common Load Impedances vs Low Frequency Output Characteristics in SE Mode

R

L

8 Ω 330 µF

32 Ω 330 µF Ą15 Hz

47,000 Ω 330 µF

C

LOWEST FREQUENCY

60 Hz

0.01 Hz

As T able 2 indicates an 8-Ω load is adequate, earphone response is good, and drive into line level inputs (a home stereo for example) is exceptional.

26

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350-mW MONO AUDIO POWER AMPLIFIER

APPLICATION INFORMATION

TPA311

SLOS207C – JANUARY 1998 – REVISED MAY 2003

SE/BTL

operation

The ability of the TP A311 to easily switch between BTL and SE modes is one of its most important cost saving features. This feature eliminates the requirement for an additional earphone amplifier in applications where internal speakers are driven in BTL mode but external earphone or speaker must be accommodated. Internal to the TP A311, two separate amplifiers drive V of the follower amplifier that drives V is in the BTL mode. When SE/BTL

– (terminal 8). When SE/BTL is held low, the amplifier is on and the TP A31 1

O

is held high, the VO– amplifier is in a high output impedance state, which configures the TP A311 as an SE driver from V mode. Control of the SE/BTL

input can be from a logic-level TTL source or, more typically , from a resistor divider

+ and VO–. The SE/BTL input (terminal 3) controls the operation

O

+ (terminal 5). IDD is reduced by approximately one-half in SE

O

network as shown in Figure 52.

C

IN

24BYPASS

SHUTDOWN

1 3

SE/BTL

Bias

Control

VO+

–

+

–

+

5

VO– 8

7

GND

C

330 µF

1 kΩ

0.1 µF

V

DD

100 kΩ

Figure 52. TPA311 Resistor Divider Network Circuit

Using a readily available 1/8-in. (3,5 mm) mono earphone jack, the control switch is closed when no plug is inserted. When closed the 100-kΩ/1-kΩ divider pulls the SE/BTL resistor is disconnected and the SE/BTL

input is pulled high. When the input goes high, the VO– amplifier is shutdown causing the BTL speaker to mute (virtually open-circuits the speaker). The V through the output capacitor (C

) into the earphone jack.

C

input low. When a plug is inserted, the 1-kΩ

+ amplifier then drives

O

using low-ESR capacitors

Low-ESR capacitors are recommended throughout this application. A real (as opposed to ideal) capacitor can be modeled simply as a resistor in series with an ideal capacitor. The voltage drop across this resistor minimizes the beneficial effects of the capacitor in the circuit. The lower the equivalent value of this resistance the more the real capacitor behaves like an ideal capacitor.

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

27

TPA311 350-mW MONO AUDIO POWER AMPLIFIER

SLOS207C – JANUARY 1998 – REVISED MAY 2003

APPLICATION INFORMATION

5-V versus 3.3-V operation

The TP A311 operates over a supply range of 2.5 V to 5.5 V. This data sheet provides full specifications for 5-V and 3.3-V operation, as these are considered to be the two most common standard voltages. There are no special considerations for 3.3-V versus 5-V operation with respect to supply bypassing, gain setting, or stability . The most important consideration is that of output power. Each amplifier in TPA311 can produce a maximum voltage swing of V opposed to V an 8-Ω load before distortion becomes significant.

Operation from 3.3-V supplies, as can be shown from the efficiency formula in equation 4, consumes approximately two-thirds the supply power for a given output-power level of operation from 5-V supplies.

O(PP)

headroom and thermal considerations

Linear power amplifiers dissipate a significant amount of heat in the package under normal operating conditions. A typical music CD requires 12 dB to 15 dB of dynamic headroom to pass the loudest portions without distortion as compared with the average power output. From the TP A31 1 data sheet, one can see that when the TPA311 is operating from a 5-V supply into a 8-Ω speaker that 350 mW peaks are available. Converting watts to dB:

– 1 V. This means, for 3.3-V operation, clipping starts to occur when V

DD

= 4 V at 5 V . The reduced voltage swing subsequently reduces maximum output power into

O(PP)

= 2.3 V as

P

W

ǒ

P

+ 10Log

dB

+ 10Log

+ –4.6 dB

Subtracting the headroom restriction to obtain the average listening level without distortion yields:

–4.6 dB* 15 dB +*19.6 dB(15 dB headroom –4.6 dB* 12 dB +*16.6 dB(12 dB headroom –4.6 dB* 9dB +*13.6 dB(9 dB headroom –4.6 dB* 6dB +*10.6 dB(6 dB headroom –4.6 dB* 3dB +*7.6 dB(3 dB headroom

Converting dB back into watts:

P

W

PdBń10

+ 10 + 11 mW (15 dB headroom)

+ 22 mW (12 dB headroom) + 44 mW (9 dB headroom) + 88 mW (6 dB headroom) + 175 mW (3 dB headroom)

Ǔ

P

ref

350 mW

ǒ

1W

P

Ǔ

)

) ) )

)

ref

28

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

350-mW MONO AUDIO POWER AMPLIFIER

DISSIPATION

SLOS207C – JANUARY 1998 – REVISED MAY 2003

APPLICATION INFORMATION

headroom and thermal considerations (continued)

This is valuable information to consider when attempting to estimate the heat dissipation requirements for the amplifier system. Comparing the absolute worst case, which is 350 mW of continuous power output with 0 dB of headroom, against 12 dB and 15 dB applications drastically affects maximum ambient temperature ratings for the system. Using the power dissipation curves for a 5-V , 8-Ω system, the internal dissipation in the TP A31 1 and maximum ambient temperatures is shown in Table 3.

Table 3. TPA311 Power Rating, 5-V, 8-Ω, BTL

TPA311

PEAK OUTPUT POWER

(mW) POWER

350 350 mW 600 350 175 mW (3 dB) 500 350 88 mW (6 dB) 380 350 44 mW (9 dB) 300 350 22 mW (12 dB) 200 350 11 mW (15 dB) 180

AVERAGE OUTPUT

POWER

DISSIPATION

(mW)

MAXIMUM AMBIENT

TEMPERATURE

0 CFM SOIC 0 CFM DGN

46°C 114°C 64°C 120°C 85°C 125°C

98°C 125°C 115°C 125°C 119°C 125°C

Table 3 shows that the TPA311 can be used to its full 350-mW rating without any heat sinking in still air up to 46°C.

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

29

PACKAGE OPTION ADDENDUM

www.ti.com

18-Jul-2006

PACKAGING INFORMATION

Orderable Device Status

(1)

Package

Type

Package

Drawing

Pins Package

Qty

Eco Plan

TPA311D ACTIVE SOIC D 8 75 Green(RoHS &

no Sb/Br)

TPA311DG4 ACTIVE SOIC D 8 75 Green (RoHS &

no Sb/Br)

TPA311DGN ACTIVE MSOP-

Power

DGN 8 80 Green (RoHS &

no Sb/Br)

PAD

TPA311DGNG4 ACTIVE MSOP-

Power

DGN 8 80 Green (RoHS &

no Sb/Br)

PAD

TPA311DGNR ACTIVE MSOP-

Power

DGN 8 2500 Green (RoHS &

no Sb/Br)

PAD

TPA311DGNRG4 ACTIVE MSOP-

Power

DGN 8 2500 Green (RoHS &

no Sb/Br)

PAD

TPA311DR ACTIVE SOIC D 8 2500 Green (RoHS &

no Sb/Br)

TPA311DRG4 ACTIVE SOIC D 8 2500 Green (RoHS &

no Sb/Br)

(1)

The marketing status values are defined as follows:

ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in

a new design.

PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device.

(2)

Lead/Ball Finish MSL Peak Temp

CU NIPDAU Level-1-260C-UNLIM

(3)

(2)

Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check

http://www.ti.com/productcontent for the latest availability information and additional product content details.

TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements

for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)

(3)

MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder

temperature.

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Addendum-Page 1

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