Texas Instruments TPA311 User manual

2001 Mixed-Signal Products
TPA311
Audio Power Amplifier
Evaluation Module
User’s Guide
SLOU013A

IMPORTANT NOTICE
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Copyright 2001, Texas Instruments Incorporated

iii
Chapter Title—Attribute Reference
Preface
Related Documentation From Texas Instruments
J TI Plug-N-Play Audio Amplifier Evaluation Platform (literature
number SLOU011) provides detailed information on the evaluation
platform and its use with TI audio evaluation modules.
J TPA311 350-mW Low-Voltage Audio Power Amplifier (literature
number SLOS207) This is the data sheet for the TPA311 audio
amplifier integrated circuit.
FCC Warning
This equipment is intended for use in a laboratory test environment only. It
generates, uses, and can radiate radio frequency energy and has not been
testedfor compliance with thelimitsof computing devices pursuanttosubpart
Jofpart 15of FCCrules, whicharedesignedtoprovidereasonableprotection
against radio frequency interference. Operation of this equipment in other
environments may cause interference with radio communications, in which
case the user at his own expense will be required to take whatever measures
may be required to correct this interference.
Trademarks
TI is a trademark of Texas Instruments Incorporated.

iv

Running Title—Attribute Reference
v
Chapter Title—Attribute Reference
Contents
1 Introduction 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1 Feature Highlights 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 Description 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3 TPA311 EVM Specifications 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 Quick Start 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.1 Precautions 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2 Quick Start List for Platform 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3 Quick Start List for Stand-Alone 2-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 Details 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1 Precautions 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2 The TPA311 Audio Amplifier Evaluation Module 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2.1 TPA311 Audio Amplifier IC 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2.2 BTL Operation 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2.3 Single-Ended Operation 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2.4 Module Gain 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2.5 Shutdown 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3 Using The TPA311 EVM With The Plug-N-Play Evaluation Platform 3-6. . . . . . . . . . . . . . .
3.3.1 Installing and Removing EVM Boards 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.2 Signal Routing 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.3 Mute/Mode 3-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.4 Power Requirements 3-10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.5 Inputs and Outputs 3-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4 Using The TPA311 EVM Stand-ALone 3-12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4.1 TPA311 EVM Connected for BTL Output 3-12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4.2 TPA311 EVM Connected for Single-Ended Output 3-13. . . . . . . . . . . . . . . . . . . . . .
3.5 TPA311 Audio Amplifier Evaluation Module Parts List 3-14. . . . . . . . . . . . . . . . . . . . . . . . . . .

Running Title—Attribute Reference
vi
Figures
1–1 The TI TPA311 Audio Amplifier Evaluation Module 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2–1 Quick Start Platform Map 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2–2 Quick Start Module Map 2-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–1 The TI Plug-N-Play Audio Amplifier Evaluation Platform 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–2 TPA311 EVM 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–3 TPA311 EVM Schematic Diagram 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–4 TPA311 Audio Amplifier IC 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–5 Platform Signal Routing and Outputs 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–6 Mute/Mode and Polarity Control 3-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–7 Typical Headphone Plug 3-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–8 TPA311 EVM Connected for Stereo BTL Output 3-12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–9 TPA311 EVM Connected for Stereo Single-Ended Output 3-13. . . . . . . . . . . . . . . . . . . . . . . . .
Tables
2–1 Typical TI Plug-N-Play Platform Jumper and Switch Settings for the TPA311 2-1. . . . . . . . . .
2–2 Platform Jumper and Switch Settings for the TPA311 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–1 TPA311 EVM Parts List 3-14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1-1
Introduction
Introduction
This chapter provides an overview of the Texas Instruments (TI) TPA311
audio amplifier evaluation module (SLOP116). It includes a list of EVM
features, a brief description of the module illustrated with a pictorial diagram,
and a list of EVM specifications.
Topic Page
1.1 Feature Highlights 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 Description 1–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3 TPA311 EVM Specifications 1–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 1

Feature Highlights
1-2 Introduction
1.1 Feature Highlights
TheTITPA311audioamplifierevaluationmoduleandtheTIplug-n-playaudio
amplifier evaluation platform include the following features:
- TPA311 Low-Voltage Audio Power Amplifier Evaluation Module
J Single channel, bridge-tied load (BTL) or single-ended operation
J 3.3-V and 5-V operation
J 350 mW output power into 8 Ωat 5 V, BTL
J Ultra-low current consumption in shutdown/mute mode
J Internal thermal and short-circuit protection
J Module gain adjustable between approximately 2 and 22
- Quick and Easy Configuration With The TI Plug-N-Play Audio Amplifier
Evaluation Platform
J Evaluation module is designed to simply plug into the platform, auto-
matically making all signal, control, and power connections
J Platform provides flexible power options
J Jumpers on the platform select power and module control options
J Switches on the platform route signals
J Platformprovides quick and easy audio inputand output connections
- Platform Power Options
J Onboard 9-V battery
J External 5-V –15-V DC VCC supply inputs
J External regulated VDD supply input
J Socket for onboard 5 V/3.3 V VDD voltage regulator EVM
J Onboard overvoltage and reverse polarity power protection
- Platform Audio Input and Output Connections
J Left and right RCA phono jack inputs
J Miniature stereo phone jack input
J Left and right RCA phono jack outputs
J Left and right compression speaker terminal outputs
J Miniature stereo headphone jack output

Description
1-3
Introduction
1.2 Description
TheTPA311 audiopower amplifierevaluationmoduleisacomplete,low-pow-
er single-channel audio power amplifier. It consists of the TI TPA311 350-mW
low-voltage audio power amplifier IC along with a small number of other parts
mounted on a circuit board that is approximately one and a quarter inches
square (Figure 1–1).
Figure 1–1.The TI TPA311 Audio Amplifier Evaluation Module
C4 R3
IN+
C2
Shutdown
R1
R2
C1
C5 C3 OUT–
GND
OUT+
GND
S1
GNDVDD
R4 EVM
Literature #
SLOP116
U1
TPA311
SE\BTL*
R5
009227
–3
Single in-line header pins are mounted to the underside of the module circuit
board to allow the EVM to be plugged into the TI plug-n-play audio amplifier
evaluationplatform, or to be wired directlyintoexisting circuitsandequipment
when used stand-alone.
The platform has room for a pair of TPA311 evaluation modules and is a
convenient vehicle for demonstrating TI’s audio power amplifier and related
evaluation modules. The EVMs simply plug into the platform, which auto-
matically provides power to the modules, interconnects them correctly, and
connectsthemtoaversatilearrayofstandardaudioinputandoutputjacksand
connectors. Easy-to-use configuration controls allow the platform and EVMs
to quickly model many possible end-equipment configurations.
There is nothing to build, nothing to solder, and nothing but the speakers
included with the platform to hook up.
1.3 TPA311 EVM Specifications
Supply voltage range, VDD 2.5 V to 5.5 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Supply current, IDD 250 mA, max. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Continuous output power, PO:8-ΩBTL, VDD=5 V: 350 mW. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
32-ΩBTL, VDD=5 V: 75 mW. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Audio input voltage, VI2 Vpp, max. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Minimum load impedance, RL8 Ω. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1-4 Introduction

2-1
Quick Start
Quick Start
Thestepsinthischapter can be followed to quickly prepare the TPA311audio
amplifier EVM for use. While using the TPA311 with the TI plug-n-play audio
amplifierevaluationplatform is a quick and easy way to connect power,signal
and control inputs, and signal outputs to the EVM using standard connectors,
the audio amplifier evaluation module can be used stand-alone by making
connectionsdirectly to the modulepins,andcanbe wired directly into existing
circuits or equipment.
Theplatform switch and jumper settings shown in Table2–1 are typical for the
TPA311 EVM and will cause the TPA311 to switch to single-ended output
mode when a plug is inserted into platform headphone jack J10.
Table 2–1. Typical TI Plug-N-Play Platform Jumper and Switch Settings for the TPA311
EVM JP6 JP7 JP8 S2 S3
TPA311 Mode X Hi Note 2 X
Notes: 1) X = Don’t care
2) SetS2 to ON when signalconditioning boardis installedin U1; set S2
to OFF when no signal conditioning board is installed.
Topic Page
2.1 Precautions 2–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2 Quick Start List for Platform 2–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3 Quick Start List for Stand-Alone 2–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 2

Precautions
2-2 Quick Start
2.1 Precautions
Power Supply Input Polarity and Maximum Voltage
Always ensure that the polarity and voltage of the external power
connected to VCC power input connector J1, J2, and/or VDD power
input connector J6 are correct. Overvoltage or reverse-polarity
power applied to these terminals can open onboard soldered-in
fuses and cause other damage to the platform, installed evaluation
modules, and/or the power source.
Inserting or Removing EVM Boards
Donot insert or remove EVMboards with power applied —damage
to the EVM board, the platform, or both may result.
Figure 2–1.Quick Start Platform Map
3
Signal Conditioning
****CAUTION****
Do not insert or remove
EVM boards with power
applied
ICC
JP4
F1
VR1
R1
JP3 JP2 JP1 AC/DC
(J2)
VCC(J1)
D1 D2 D3
D4 J2
J3 J4 J5
AC/DC
In
VCC
In
+
J1
DC
SOURCE
LED1 VCC
LED2 VDD
R2
JP5 IDD
B1
U6
POWER
SUPPLY
U3 U4
U5
U1
U2
Audio
Power
Amps
OnOff ConditioningS2
J7 J8 Right
Out Left
Out
+–+–
JP6
Mode
Mute
Spk(U2-U4)
JP8
J9 Left
Out
JP7
S3 HP Source
U2-U4
U5
Polarity
Lo
Hi
HP(U5)
C3 C2
++
R3
R4 R5
J10
Stereo
HP Out
TP1
GND
Plug-N-PlayAudio Amplifier
Evaluation Platform
SLOP097 Rev. C.1
Stereo
In
Right
In Left
In
J6 In/Out VDD
F2
VR2
+
DC
Power
In/Out
Speaker
Output
Headphone
Output
Audio
Input
Power
Input
Batt
C1+
Right
Out
On Off Pwr
S1
TEXAS INSTRUMENTS 1997
111
10
9
7b
7b
7a
7b
5
4
7b
26

Quick Start List for Platform
2-3
Quick Start
2.2 Quick Start List for Platform
Use the following steps when using the TPA311 EVM with the TI plug-n-play
audio amplifier evaluation platform (see the platform user’s guide, SLOU011,
for additional details). Numbered callouts for selected steps are shown in
Figure 2–1 and details appear in Chapter 3.
- Platform preparations
1) EnsurethatallexternalpowersourcesaresettoOFFandthattheplatform
power switch S1 is set to OFF
2) Install a TPA311 module in platform sockets U3 and U4 for stereo
operation (or a module in either U3 or U4 for single channel operation),
taking care to align the module pins correctly
3) Use switch S2 to select or bypass the signal conditioning EVM (U1)
4) Set control signal Polarity jumper JP8 to Hi
5) Set jumper JP6 to select the Mode control input (causes the TPA311 to
switch to the single-ended output mode if a plug is inserted into platform
headphone jack J10)
6) If the headphone Jack (J10) output will be used, set Hp source switch S3
to U2–U4.
Table 2–2. Platform Jumper and Switch Settings for the TPA311
EVM JP6 JP7 JP8 S2 S3
TPA311 Mode X Hi Note 2 X
Notes: 1) X = Don’t care
2) SetS2 to ON whensignal conditioning boardis installed inU1; set S2
to OFF when no signal conditioning board is installed.
- Power supply
7) Select and connect the power supply:
a) Connectan external regulated powersupplyset to a voltagebetween
2.5Vand 5.5 V to platform VDD power input connector J6 taking care
to observe marked polarity, or
b) InstallavoltageregulatorEVM(SLVP097orequiv.)inplatformsocket
U6. Install a 9-V battery in B1 or connect a 7 V –12 V power source
to a platform VCC power input J1 or J2 and jumper the appropriate
power input (see platform user’s guide)
- Inputs and outputs
8) Ensure that signal source level adjustments and EVM gain, R4, are set to
minimum
9) Connect the audio source to left and right RCA phono jacks J3 and J5 or
stereo miniature phone jack J4
10) Connect 8-Ω–32-Ωspeakers to left and right RCA jacks J7 and J9 or to
stripped wire connectors J8
- Power-up
11) Verifycorrect voltageandinput polarity and set the externalpowersupply
toON. If VCC andan onboardregulator EVMareusedtoprovideVDD,set
platform power switch S1 to ON
PlatformLED2shouldlightindicatingthepresenceofVDD,andtheevaluation
modules installed on the platform should begin operation.
12) Adjust the signal source level and EVM gain level (R4) as needed

Quick Start List for Stand-Alone
2-4 Quick Start
2.3 Quick Start List for Stand-Alone
Use the following steps to use the TPA311 EVM stand-alone or when
connecting it into existing circuits or equipment. Connections to the TPA311
module header pins can be made via individual sockets, wire-wrapping, or
solderingtothepins,eitheronthetoporthebottomofthemodulecircuitboard.
Numbered callouts for selected steps are shown in Figure 2–2 and details
appear in Chapter 3.
Figure 2–2.Quick Start Module Map
5
2
Gain Adjust
67
4
C4 R3
IN+
C2
Shutdown
R1
R2
C1
C5 C3 OUT–
GND
OUT+
GND
S1
GNDVDD
R4 EVM
Literature #
SLOP116
U1
TPA311
SE\BTL*
R5
009227
–3
- Power supply
1) Ensure that all external power sources are set to OFF
2) Connectanexternalregulated powersupplysetto5 Vtothe moduleVDD
and GND pins taking care to observe marked polarity
- Inputs and outputs
3) Ensurethat signal source level adjustmentsandEVM gain (R4) are setto
minimum
4) Connect the audio source to the module IN+ and GND pins taking care to
observe marked polarity
5) Connect the Shutdown pin to VDD through a normally open switch
6) For BTL output, connect an 8-Ω–32-Ωspeaker to the module OUT+ and
OUT–pins, or
7) For single-ended output, connect a headphone or an 8-Ω–32-Ωspeaker
to the module OUT+ and GND pins through a 33 µF to 1000 µF output-
coupling capacitor (figure 3–9)
- Power-up
8) Verifycorrect voltage and input polarity andsetthe external power supply
to ON
The EVM should begin operation.
9) Adjust the signal source level and EVM gain level (R4) as needed

3-1
Details
Details
This chapter provides details on the TPA311 IC, the evaluation module, and
thestepsintheQuick-StartList,additionalapplicationinformation,andaparts
list for the TPA311 evaluation module.
Topic Page
3.1 Precautions 3–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2 The TPA311 Audio Power Amplifier Evaluation Module 3–3. . . . . . . . . . .
3.3 Using The TPA311 EVM With The Plug-N-Play
Evaluation Platform 3–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4 Using The TPA311 EVM Stand-Alone 3–12. . . . . . . . . . . . . . . . . . . . . . . . .
3.5 TPA311 Audio Power Amplifier Evaluation Module Parts List 3–14. . .
Chapter 3

Precautions
3-2 Details
3.1 Precautions
Power Supply Input Polarity and Maximum Voltage
Always ensure that the polarity and voltage of the external power
connected to VCC power input connector J1, J2, and/or VDD power
input connector J6 are correct. Overvoltage or reverse-polarity
power applied to these terminals can open onboard soldered-in
fuses and cause other damage to the platform, installed evaluation
modules, and/or the power source.
Inserting or Removing EVM Boards
Donot insert or remove EVMboards with power applied —damage
to the EVM board, the platform, or both may result.
Figure 3–1.The TI Plug-N-Play Audio Amplifier Evaluation Platform
Signal Conditioning
****CAUTION****
Do not insert or remove
EVM boards with power
applied
ICC
JP4
F1
VR1
R1
JP3 JP2 JP1 AC/DC
(J2)
VCC(J1)
D1 D2 D3
D4 J2
J3 J4 J5
AC/DC
In
VCC
In
+
J1
DC
SOURCE
LED1 VCC
LED2 VDD
R2
JP5 IDD
B1
U6
POWER
SUPPLY
U3 U4
U5
U1
U2
Audio
Power
Amps
OnOff ConditioningS2
J7 J8 Right
Out Left
Out
+–+–
JP6
Mode
Mute
Spk(U2-U4)
JP8
J9 Left
Out
JP7
S3 HP Source
U2-U4
U5
Polarity
Lo
Hi
HP(U5)
C3 C2
++
R3
R4 R5
J10
Stereo
HP Out
TP1
GND
Plug-N-PlayAudio Amplifier
Evaluation Platform
SLOP097 Rev. C.1
Stereo
In
Right
In Left
In
J6 In/Out VDD
F2
VR2
+
DC
Power
In/Out
Speaker
Output
Headphone
Output
Audio
Input
Power
Input
Batt
C1+
Right
Out
On Off Pwr
S1
TEXAS INSTRUMENTS 1997

The TPA311 Audio Power Amplifier Evaluation Module
3-3
Details
3.2 The TPA311 Audio Power Amplifier Evaluation Module
TheTPA311audiopoweramplifierevaluationmoduleispoweredbyaTPA311
350-mWlow-poweraudioamplifierICandincludeson-boardgainadjustment,
a shutdown control signal input with on-board switch, and can be operated in
either the BTL or single-ended output mode.
The module can be used with the TI plug-n-play audio amplifier evaluation
platform (Figure 3–1) or wired directly into circuits or equipment. The module
has single in-line header connector pins mounted to the under side of the
board. These pins allow the module to be plugged into the TI platform, which
automatically makes all the signal input and output, power, and control
connections to the module.
The module connection pins are on 0.1-inch centers to allow easy use with
standardperfboardandplugboard-basedprototypingsystems,ortobewired
directly into existing circuits and equipment when used stand-alone.
The module appears in Figure 3–2 and its schematic is shown in Figure 3–3.
Figure 3–2.TPA311 EVM
C4 R3
IN+
C2
Shutdown
R1
R2
C1
C5 C3 OUT–
GND
OUT+
GND
S1
GNDVDD
R4 EVM
Literature #
SLOP116
U1
TPA311
SE\BTL*
R5
009227
–3
Figure 3–3.TPA311 EVM Schematic Diagram
C2
2.2 µF
C1
1 µF
R1
20 kΩ
Audio Input+
GND
Shutdown
S1
C4
5 pF
OUT–
GND
OUT+
R3
20 kΩR4 200 kΩ
R2
20 kΩ
No
C5
10 µF
C3
2.2 µF
Shutdown
Bypass
SE/BTL
In
VO–
GND
VDD
VO+
8
7
6
5
1
2
3
4
GND
VDD
2.5 V to 5.5 V
+
SE/BTL
R5
100 kΩ

The TPA311 Audio Power Amplifier Evaluation Module
3-4 Details
3.2.1 TPA311 Audio Amplifier IC
TheTPA311audioamplifierICisaCMOSdeviceintendedprimarilyforbridge-
tied load (BTL) operation in battery-powered applications. It is supplied in a
verysmallsurface-mountpackageandhasbeendesignedtooperatefromlow
supply voltages (between approximately 2.5 V and 5.5 V) and deliver up to
approximately 350 mW into an 8-Ω,BTL (Figure 3–4).Typicalapplicationsin-
cludeportablephones,toys,games,andsimilarhand-heldaudioapplications.
Figure 3–4.TPA311 Amplifier IC
5VO+
4
IN
VO–
8
_
_
+
+
7
2
VDD/2 VDD
GND
6
SE/BTL
Shutdown
3
1
Bypass
Bias
Control
The IC includes two separate internal amplifiers and can operate in either the
bridged-tied load (BTL) mode or the single-ended mode as selected by the
SE/BTL pin. In the BTL mode, the two amplifiers operate 180°out-of-phase
with each other for increased power. The speaker load is connected directly
across VO+ and VO–, and neither line is connected to ground. BTL operation
providesmanybenefits,includingquadrupletheoutputpowerofsingle-ended
operation and no need for bulky output coupling capacitors. In the
single-ended mode, one internal amplifier is turned off and the speaker load
isconnectedbetweentheVO+terminal,throughanoutputcouplingcapacitor,
and system ground. For more information, see the TPA311 amplifier IC data
sheet, TI literature number SLOS207.
3.2.2 BTL Operation
To operate in the bridge-tied load output mode, the module SE/BTL control
inputterminalmustbeheldlow.ThemoduleoutputsignalfromOUT+mustgo
through the speaker load and be returned directly to OUT–,and not to system
ground. This requires that the OUT–line be isolated not only from system
ground,butalsofromtheOUT–linesofanyotheramplifiersinthesystem.The
platform provides such isolated output lines from the amplifier EVM sockets
directly to separate left and right speaker connectors.

The TPA311 Audio Power Amplifier Evaluation Module
3-5
Details
3.2.3 SIngle-Ended Operation
Forsingle-endedoperation,themoduleSE/BTLcontrolinputpinmustbeheld
high. The speaker (or headphone) load is connected to the module OUT+
output pin through a coupling capacitor, and to platform/system ground. A
470-µF electrolytic coupling capacitor is provided on the platform in the signal
path to the headphone output jack for this purpose and a control signal from
the platform headphone jack can be routed to the module control input pin to
switch the TPA311 IC to the single-ended mode.
In the single-ended mode, the amplifier inside the TPA311 IC that drives the
OUT–line does not operate and does not dissipate any power. The OUT–pin
goesintoahigh-impedancestateandcanbeleftconnectedorallowedtofloat.
3.2.4 Module Gain
TheTPA311evaluationmodulecanbesetforanoverallgainofbetween2and
22 by adjustment of the the onboard gain control, R4. The TPA311 amplifier
IC,as mostother amplifiers,exhibitsits bestdistortionand noiseperformance
at lower gain levels (see the TPA311 data sheet). Even so, the TPA311 at its
highest gain setting has significantly less distortion than most low-cost
speakers.
Gain versus total harmonic distortion (THD) should be considered in each
application. Both the module input signal level and the TPA311 module gain
should be adjusted to obtain the lowest overall distortion level for a particular
overall gain. A quick rule of thumb (everything else being equal): the module
inputsignallevelshouldbeashighaspossiblewithout clippingor overloading
the TPA311 input, and the TPA311 gain kept as low as possible.
3.2.5 Shutdown
When the shutdown terminal of the TPA311 amplifier IC is taken high, the IC
ceasesoperationandentersanultralow-powerstate.Thisisaccomplishedby
applying a control signal to the module shutdown pin or by pressing the shut-
down switch, S1, on the module. When the control signal goes low or is re-
moved (or the switch is released), amplifier operation resumes.
The plug-n-play platform can generate the shutdown (mute) signal for the
moduleeither when a plug is insertedintotheplatformheadphone output jack
or when the plug is removed, as selected by a platform jumper (JP8).

Using The TPA311 EVM With the Plug-N-Play Evaluation Platform
3-6 Details
3.3 Using The TPA311 EVM With the Plug-N-Play Evaluation Platform
The TPA311 audio amplifier evaluation module was designed to be used with
the TI plug-n-play audio amplifier evaluation platform. It simply plugs into
socket U3 or U4.
ThefollowingparagraphsprovideadditionaldetailsforusingtheTPA311EVM
with the platform.
3.3.1 Installing and Removing EVM Boards
TI plug-n-play evaluation modules use single-in-line header pins installed on
the underside of the module circuit board to plug into sockets on the platform.
The EVM pins and the platform sockets are keyed such that only the correct
type of EVM can be installed in a particular socket, and then only with the
proper orientation.
Evaluation modules are easily removed from the platform by simply prying
them up and lifting them out of their sockets. Care must be taken, however, to
prevent bending the pins.
3.3.1.1 EVM Insertion
1) Remove all power from the evaluation platform
2) Locate socket U3 or U4 on the platform
3) Orient the module correctly
4) Carefully align the pins of the module with the socket pin receptacles
5) Gently press the module into place
6) Check to be sure that all pins are seated properly and that none are bent
over
3.3.1.2 EVM Removal
1) Remove all power from the evaluation platform
2) Using an appropriate tool as a lever, gently pry up one side of the module
a small amount
3) Changetothe oppositesideofthemoduleanduse thetooltoprythatside
up a small amount
4) Alternate between sides, prying the module up a little more each time to
avoid bending the pins, until it comes loose from the socket
5) Lift the EVM off of the platform