Texas Instruments TPA005D02 User Manual

TPA005D02 Class D Stereo
Audio Power Amplifier
Evaluation Module

User’s Guide

October 1998 Mixed-Signal Products

SLOU032A

IMPORTANT NOTICE

T exas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue
any product or service without notice, and advise customers to obtain the latest version of relevant information
to verify, before placing orders, that information being relied on is current and complete. All products are sold
subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those
pertaining to warranty, patent infringement, and limitation of liability.

TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in
accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent
TI deems necessary to support this warranty . Specific testing of all parameters of each device is not necessarily
performed, except those mandated by government requirements.

CERT AIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF
DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE (“CRITICAL
APPLICATIONS”). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, AUTHORIZED, OR
WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT DEVICES OR SYSTEMS OR OTHER
CRITICAL APPLICA TIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERST OOD TO
BE FULLY AT THE CUSTOMER’S RISK.

In order to minimize risks associated with the customer’s applications, adequate design and operating
safeguards must be provided by the customer to minimize inherent or procedural hazards.

TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent
that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other
intellectual property right of TI covering or relating to any combination, machine, or process in which such
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party’s products or services does not constitute TI’s approval, warranty or endorsement thereof.

Copyright  1998, Texas Instruments Incorporated

Related Documentation From Texas Instruments

J

TI Plug-N-Play Audio Amplifier Evaluation Platform

number SLOU011) provides detailed information on the evaluation
platform and its use with TI audio evaluation modules.

J

TPA005D02 CLASS D STEREO AUDIO POWER AMPLIFIER

(literature number SLOS227) This is the data sheet for the
TPA005D02 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
tested for compliance with the limits of computing devices pursuant to subpart
J of part 15 of FCC rules, which are designed to provide reasonable protection
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.

Preface

(literature

Trademarks

TI is a trademark of Texas Instruments Incorporated.

Chapter Title—Attribute Reference

iii

iv

Running Title—Attribute Reference

Contents

1 Introduction 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.1 Feature Highlights 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.2 Description 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.3 TP A0202 EVM Specifications 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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 TPA005D02 Audio Power Amplifier Evaluation Module 3-3. . . . . . . . . . . . . . . . . . . . . .

3.2.1 TPA005D02 Class D Stereo Audio Amplifier IC 3-4. . . . . . . . . . . . . . . . . . . . . . . . . .

3.2.2 Overview of Class D Audio Amplifiers 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.2.3 EVM Design Considerations 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.2.4 Efficiency of Class D vs. Linear Operation 3-15. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.3 Using The TPA005D02 Class D EVM With the Plug-N-Play Platform 3-22. . . . . . . . . . . . .

3.3.1 Installing and Removing EVM Boards 3-22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.3.2 Module Switches 3-23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.3.3 Signal Routing 3-24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.3.4 Mute 3-25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.3.5 Power Requirements 3-26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.3.6 Inputs and Outputs 3-27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.4 Using The TPA005D02 Class D EVM Stand-Alone 3-28. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.4.1 TPA005D02 Class D EVM Connected for BTL Output 3-28. . . . . . . . . . . . . . . . . . .

3.5 TPA005D02 Audio Power Amplifier Evaluation Module Parts List 3-29. . . . . . . . . . . . . . . .

3.6 TPA005D02 Class D EVM Measured Characteristics 3-30. . . . . . . . . . . . . . . . . . . . . . . . . . .

3.7 TPA005D02 Class D EVM PCB Layers 3-33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter Title—Attribute Reference

v

Running Title—Attribute Reference

Figures

1–1 The TI TPA005D02 Class D Stereo Audio Amplifier Evaluation Module 1-3. . . . . . . . . . . . . . .

2–1 Quick Start Platform Map 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–1 The TI Plug-N-Play Audio Amplifier Evaluation Platform 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–2 TPA005D02 Class D EVM 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–3 TPA005D02 Class D EVM Schematic Diagram 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–4 Class D Functional Diagram 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–5 Class D Input and Output Waveforms 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–6 Single-Ended Class D Output FIlter 3-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–7 Low-Pass Filter for Bridged Application 3-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–8 Resulting Bridged Output Filter 3-10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–9 Half-Bridge Class D Output Stage 3-15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–10 Class D Currents 3-16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–11 Class D Voltages 3-16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–12 H-Bridge Class D Output Stage 3-17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–13 Output Transistor Simplification for Conduction Loss Calculation 3-18. . . . . . . . . . . . . . . . . . .

3–14 Output Switching Losses 3-19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–15 Audio Signal Showing Peak and RMS Power 3-20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–16 Audio Signal Showing Peak and RMS Power (with Music Applied) 3-20. . . . . . . . . . . . . . . . . .

3–17 Supply Current vs Peak Output Voltage of TPA005D02 vs TPA0202 with Music Input 3-21.

3–18 Platform Signal Routing and Outputs 3-24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–19 Mute/Mode and Polarity Control 3-25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–20 Typical Headphone Plug 3-27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–21. TPA005D02 Class D EVM Connected for Stereo BTL Output 3-28. . . . . . . . . . . . . . . . . . . . . . . .

3–22. Frequency Response 3-30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–23. Distortion versus Output Power 3-31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–24. Distortion versus Frequency 3-32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–25. Crosstalk versus Frequency 3-32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–26. TPA005D02 Class D EVM Silkscreen 3-33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–27. TPA005D02 Class D EVM Top Layer 3-33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–28. TPA005D02 Class D EVM 2nd Layer 3-34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–29. TPA005D02 Class D EVM 3rd Layer 3-34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–30. TPA005D02 Class D EVM Bottom Layer 3-35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

T ables

2–1 Typical TI Plug-N-Play Platform Jumper and Switch Settings for the

2–2 Platform Jumper and Switch Settings for the TPA005D02 2-3. . . . . . . . . . . . . . . . . . . . . . . . . .

3–1 TPA005D02 Class D EVM Fault Indicator Table 3-14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–2 Efficiency vs Output Power in 5-V 8-W H-Bridge Systems 3-19. . . . . . . . . . . . . . . . . . . . . . . . .

3–3 TPA005D02 Class D EVM Parts List 3-29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

vi

TPA005D02 Class D EVM 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter 1

Introduction

This chapter provides an overview of the T exas Instruments (TI) TP A005D02
Class D Stereo Audio Amplifier Evaluation Module (SLOP223). 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 TP A005D02 Class D EVM Specifications 1–4. . . . . . . . . . . . . . . . . . . . . . . .

Introduction

1-1

Feature Highlights

1.1 Feature Highlights

The TI TP A005D02 Class D Stereo Audio Amplifier Evaluation Module and the
TI Plug-N-Play Audio Amplifier Evaluation Platform include the following
features:

-

TPA005D02 Class D Stereo Audio Power Amplifier Evaluation Module

J

J

J

J

J

J

J

-

Quick and Easy Configuration with The TI Plug-N-Play Audio Amplifier
Evaluation Platform

J

External depop circuitry to eliminate turn-on transients in outputs
Dual channel, bridge-tied load (BTL) only operation
5-V operation
2 W per channel output power into 4 Ω at 5 V, BTL
Low current consumption in shutdown/mute mode (400 µA)
Module gain set to 24 dB
High efficiency

Evaluation module is designed to simply plug into the platform,
automatically 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

Platform provides quick and easy audio input and output connections

-

Platform Power Options

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

1-2

Introduction

Description

1.2 Description

The TP A005D02 Class D Stereo Audio Power Amplifier Evaluation Module is
a complete, 2-Watt per channel stereo audio power amplifier . It consists of the
TI TPA005D02 Class D Stereo Audio Power Amplifier IC along with a small
number of other parts mounted on a circuit board that measures approximately
2

1/4

inches by 1

Figure 1–1.The TI TPA005D02 Class D Stereo Audio Amplifier Evaluation Module

3/4

inches (Figure 1–1).

GND
RIN+
RIN–

Shutdown
C1

R2
R1

Q1
LIN–

LIN+

GND

Mute

T exas Instruments

R6 R7

1998

C4
C2
C3

C5

R3

R4
R5

D1

S1

SLOP223

C8

S2

C6

C7

D2

1

C10

VDD

GND

C19

C20

L1

C14

L2

C21

L3

U1

L4

GND

D3

+

C12

C13

C9

C17

C15

+

C11

VDD

TPA005D02 EVM Board Rev. A

C24

C23

C25

C26

C22

C27

Rout+

Rout–

Mute

Lout–

Lout+

Single in-line header pins extend from the underside of the module circuit
board to allow the EVM to either be plugged into the TI Plug-N-Play Audio Am­plifier Evaluation Platform, or to be wired directly into existing circuits and
equipment when used stand-alone.

The platform has room for a single TPA005D02 class D evaluation module and
is a convenient vehicle for demonstrating TI’s audio power amplifier and
related evaluation modules. The EVMs simply plug into the platform, which
automatically provides power to the modules, interconnects them correctly,
and connects them to a versatile array of standard audio input and output jacks
and 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.

Introduction

1-3

TPA005D02 Class D EVM Specifications

1.3 TPA005D02 Class D EVM Specifications

Supply voltage range, V
Supply current, I

DD

DD

Continuous output power per channel, P
Audio input voltage, V
Load impedance, R

: 0.47 Vpp max. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

I

L

4.5 V to 5.5 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.8 A max. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

:4-Ω BTL, VDD=5 V 2 W. . . . . . . . . . . . . . . . . . . . . .

O

4 Ω. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1-4

Introduction

Chapter 2

Quick Start

Follow the steps in this chapter to quickly prepare the TPA005D02 Class D
Stereo Audio Amplifier EVM for use. Using the TP A005D02 class D EVM with
the TI Plug-N-Play Audio Amplifier Evaluation Platform is a quick and easy way
to connect power, signal and control inputs, and signal outputs to the EVM
using standard connectors. However, the audio amplifier evaluation module
can be used stand-alone by making connections directly to the module pins,
and it can be wired directly into existing circuits or equipment.

The platform switch and jumper settings shown in T able 2–1 are typical for the
TPA005D02 class D EVM.

Table 2–1. Typical TI Plug-N-Play Platform Jumper and Switch Settings for the
TPA005D02 Class D EVM

EVM JP6 JP7 JP8 S2 S3

P-N-P Platform Mute X Lo Note 2 U5

Notes: 1) X = Don’t care

2) Set S2 to ON when signal conditioning board is installed in U1; set S2
to OFF when no signal conditioning board is installed.

T opic Page

2.1 Precautions 2–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.2 Quick Start List for Platform 2–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.3 Quick Start List for Stand-Alone 2–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Quick Start

2-1

Precautions

2.1 Precautions

Power Supply Input Polarity and Maximum Voltage
Always ensure that the polarity and voltage of the external power

connected to V
input connector J6 are correct. Overvoltage or reverse-polarity

power input connector J1, J2, and/or VDD power

CC

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
Do not insert or remove EVM boards with power applied — damage

to the EVM board, the platform, or both may result.

Figure 2–1.

VCC

In

+

Audio
Input

9

AC/DC

In

Power

Input

7b

Quick Start Platform Map

7b

JP3

JP2

JP1

SOURCE

DC

VCC(J1)

J1

D4

J2

D3

Right

J3

In

Stereo

J4

In

Left

J5

In

TEXAS

INSTRUMENTS

1997

AC/DC

(J2)

D2

Signal Conditioning

Plug-N-Play Audio Amplifier
Evaluation Platform
SLOP097 Rev. C.1

F1

Batt

VR1

D1

LED1

VCC

****CAUTION****
Do not insert or remove
EVM boards with power

applied

C1+

R1

U1

117

Off Pwr

GND

On

S1

Audio
Power
Amps

OnOff

ConditioningS2

TP1

ICC
JP4

B1

IDD

U5

JP5

7b

U3 U4

R2

U2-U4

U5

HP

Source

SUPPLY

U2

HP(U5)

Polarity

S3

R3

R4

7b

POWER

U6

LED2

VDD

JP6

Lo
Hi

JP7

JP8

+

+

F2

J7

Right

Out

J8

+–+–
Right

Out

Left

Out

Mode
Mute

Spk(U2-U4)

J9

Left

Out

Stereo

C3 C2

HP Out

VR2

In/Out

VDD

J10

R5

DC
Power
In/Out

+

J6

Speaker
Output

Headphone
Output

7a

10

5

2-2

3

2

6

4

Quick Start

2.2 Quick Start List for Platform

Follow these steps when using the TP A005D02 class D EVM with the TI Plug­N-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

Quick Start List for Platform

1) Ensure that all external power sources are set to
power switch S1 is set to

OFF.

2) Install a TP A005D02 module in platform socket U2, 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

5) Set jumper JP6 to select the

Mute

control input (causes the TP A005D02

Lo.

to mute if a plug is inserted into platform headphone jack J10).

U5

6) Set switch S3 to

. It is important that S3 always be in the U5 position

to avoid possible damage to the EVM and headphones when the
TPA005D02 class D EVM is installed in platform socket U2.

Table 2–2. Platform Jumper and Switch Settings for the TPA005D02

EVM JP6 JP7 JP8 S2 S3

P-N-P Platform Mute X Lo Note 2 U5

Notes: 1) X = Don’t care

ON

2) Set S2 to
to

OFF

-

Power supply

7) Select and connect the power supply (ensure power supply is set to
a) Connect an external regulated power supply set to 5 V to platform V

power input connector J6 taking care to observe marked polarity,
or

b) Install a voltage regulator EVM (SL VP097 or equiv .) in platform socket

U6. Connect a 7 V – 12 V power source to a platform V
J1 or J2 and jumper the appropriate power input (see platform user’s

guide).

when signal conditioning board is installed in U1; set S2

when no signal conditioning board is installed.

OFF

and that the platform

power input

CC

OFF

):

DD

-

Inputs and outputs

8) Ensure that the audio signal source level is 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 4-Ω – 8-Ω speakers (use 4-Ω for best performance) to left and
right RCA jacks J7 and J9 or to stripped wire speaker connectors J8.

-

Power Up

1 1) V erify correct voltage and input polarity and set the external power supply

to

ON.

If VCC and an onboard regulator EVM are used to provide VDD, set

platform power switch S1 to

ON.

Platform LED2 should light indicating the presence of VDD, and the evaluation
modules installed on the platform should begin operation.

12) Adjust the signal source level as needed.

Quick Start

2-3

Quick Start List for Stand-Alone

2.3 Quick Start List for Stand-Alone

Follow these steps to use the TPA005D02 class D EVM stand-alone or to
connect it into existing circuits or equipment. Connections to the TP A005D02
module header pins can be made via individual sockets, wire-wrapping, or
soldering to the pins, either on the top or the bottom of the module circuit board.

-

Power supply

1) Ensure that all external power sources are set to

OFF.

2) Connect an external regulated power supply set to 5 V to the module VDD
and GND pins taking care to observe marked polarity. Separate right
channel and left channel VDD supplies can be connected, or a single
supply can be used for both.

-

Inputs and outputs

3) Ensure that audio signal source level adjustments are set to minimum.

4) Connect the audio source to the module RIN+/RIN– and LIN+/LIN– pins,
taking care to observe marked polarity.

5) Connect a control signal to the module MUTE pin, if necessary . The control
signal should be high or floating for normal operation and low to mute the
module.

6) Connect a 4-Ω – 8-Ω speaker (use 4-Ω for best performance) to the
module ROUT+/ROUT– pins and another speaker to the LOUT+/LOUT–
pins, taking care to observe marked polarity.

-

Power-up

7) Verify correct voltage and input polarity and set the external power supply
to

ON.

2-4

The EVM should begin operation.

8) Adjust the signal source level as needed.

Quick Start

Chapter 3

Details

This chapter provides details on the TPA005D02 IC, the evaluation module,
and the steps in the Quick-Start List, a discussion on class D amplifiers,
additional application information, a parts list for the TPA005D02 class D
evaluation module, module performance graphs, and module PCB layer
illustrations.

Topic Page

3.1 Precautions 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.2 The TPA005D02 Audio Power Amplifier Evaluation Module 3-3. . . . . . .

3.3 Using The TPA005D02 Class D EVM With the P-N-P Platform 3-22. . . .

3.4 Using The TPA005D02 Class D EVM Stand-Alone 3-28. . . . . . . . . . . . . . .

3.5 TP A005D02 Audio Power Amplifier Evaluation Module Parts List 3-29

3.6 TP A005D02 Class D EVM Measured Characteristics 3-30. . . . . . . . . . . . .

3.7 TP A005D02 Class D EVM PCB Layers 3-33. . . . . . . . . . . . . . . . . . . . . . . . . .

Details

3-1

Precautions

3.1 Precautions

Power Supply Input Polarity and Maximum Voltage
Always ensure that the polarity and voltage of the external power

connected to V
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
Do not insert or remove EVM boards 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

Power

Input

Audio
Input

In

+

AC/DC

In

VCC

D4

J2

In

In

In

J1

SOURCE

DC

VCC(J1)

D3

Right

J3

Stereo

J4

Left

J5

JP1

JP3

AC/DC

(J2)

D2

JP2

D1

Batt

VR1

F1

VCC

LED1

Signal Conditioning

C1+

R1

U1

power input connector J1, J2, and/or VDD power

CC

On

Off Pwr

S1

ICC
JP4

SUPPLY

POWER

B1

JP5

IDD

LED2

VDD

R2

Audio
Power
Amps

U3 U4

U2

OnOff

ConditioningS2

U6

J7

Out

Out

Out

VR2

F2

DC
Power
In/Out

+

J6

In/Out

VDD

Right

J8

+–+–
Right

Speaker
Output

Left

3-2

TEXAS

INSTRUMENTS

1997

Plug-N-Play Audio Amplifier
Evaluation Platform
SLOP097 Rev. C.1

****CAUTION****
Do not insert or remove
EVM boards with power

applied

GND

TP1

U5

U2-U4

U5

HP

Source

HP(U5)

S3

R3

R4

JP6

Polarity

Lo

Hi

JP7

+

+

Mode
Mute

Spk(U2-U4)

Out

JP8

C3 C2

HP Out

J9

Left

Stereo

Headphone
Output

J10

R5

Details

The TPA005D02 Audio Power Amplifier Evaluation Module

3.2 The TPA005D02 Audio Power Amplifier Evaluation Module

The TP A005D02 Class D Stereo Audio Power Amplifier Evaluation Module is
powered by a TPA005D02 class D stereo power amplifier integrated circuit
capable of delivering greater than 2 W of continuous power per channel into
4-Ω loads. The amplifier IC operates in the bridge-tied load mode for maximum
efficiency. The evaluation module includes onboard switches for muting and
shutdown and a control input pin for muting. A pair of indicator LEDs are
mounted on the module to display power supply undervoltage and amplifier
IC thermal status.

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 underside 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
standard perf board and plug board-based prototyping systems. Or, the EVM
can be wired 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.TPA005D02 Class D EVM

T exas Instruments

R6 R7

1998

GND
RIN+
RIN–

Shutdown
C1

R2
R1

Q1

LIN–
LIN+

GND

Mute

R3

C4
C2
C3

C5

R4
R5

D1

S1

SLOP223

C8

S2

C6

C7

D2

1

C10

VDD

GND

C19

C20

L1

C14

L2

C21

L3

U1

L4

GND

D3

+

C12

C13

C9

C17

C15

+

C11

VDD

TPA005D02 EVM Board Rev. A

C24

C23

C25

C26

C22

C27

Rout+

Rout–

Mute

Lout–

Lout+

Details

3-3

The TPA005D02 Audio Power Amplifier Evaluation Module

Figure 3–3.TPA005D02 Class D EVM Schematic Diagram

V
V

GND
GND

MUTE

LIN+
LIN–

RIN+

RIN–

DD
DD

R5

100 KΩ

R1

20 KΩ

V

DD

Mute

C21

0.047 µF

C20

0.047 µF

V

DD

C1

1 µF

R2

1 KΩ

R3

D1

20 KΩ

3.9 V

S2

1 µF

C6

470 pF

C8

C2

1 µF

C3

470 pF

C4

470 pF

C5

C19

1 µF

1 µFC7

1 µF

Q1

2N3906

Shutdown

S1

1
2

3
5
4
6
7

44
45
43
17
19

30
48

47
46
20
22
28
26
23

24
25

100 KΩ

SHUTDOWN
MUTE

AGND
LINP

LINN
LCOMP

AGND
RINP

RINN
RCOMP
NC
NC
NC
COSC
AGND
AGND
AGND
VCP
LSBIAS
CP4
CP3

CP2
CP1

PowerPAD

R4

U1

TPA005D02

LPV

DD

LPV

DD

V

DD

PV

DD

RPV

DD

RPV

DD

PV

DD

FAULT0
FAULT1

LOUTP
LOUTP

PGND
PGND

LOUTN
LOUTN
ROUTP
ROUTP

PGND

PGND
ROUTN
ROUTN

NC
NC

V2P5

PGND

C13
1 µ

F

9
16

8
21

40
33

32
42

L4

µH

15

L3

15

µH

L1

15 µH

L2

15 µH

D3

C18

1 µF

41
10
11
12
13
14
15
39
38
37
36
35
34

18
31
29
27

C9

1 µF

C26

0.22 µF

C17
1 µF

C25

0.22 µF

0.22 µF

C24

0.22 µF

C27

+

F

F

µ

10

D2

R7

C23
1 µF

C22
1 µF

µ

220

R6

1 KΩ

F
1 µ

1 KΩ

LOUT+

LOUT–
ROUT+

ROUT–

F
1 µ

C16

C12

C14

C10

V

DD

C11

C15

+

F

F

µ

µ

10

220

V

DD

3.2.1 TPA005D02 Class D Stereo Audio Amplifier IC

The TPA005D02 Class D Stereo Audio Power Amplifier integrated circuit
converts low-level audio into pulse-width-modulated (PWM) signals, which
result in an audio output with a 24-dB increase in amplitude. Designed
primarily for BTL operation at a supply voltage of 5 V, each channel of the
TP A005D02 amplifier IC is capable of 2 W of continuous output power into a
4-Ω load at 0.8% total harmonic distortion + noise (THD+N) over a frequency
range of 20Hz – 20kHz.

The device is provided in a very small 48-pin thermally-enhanced PowerP AD
TSSOP surface-mount package (DCA) and consumes only 400 µA in
shutdown mode, making the TPA005D02 an excellent choice for portable
battery-powered applications.

3-4

Details

The TPA005D02 Audio Power Amplifier Evaluation Module

3.2.2 Overview of Class D Audio Amplifiers

Class D audio amplifiers are very similar in operation to switch-mode power
supplies in that both compare an input signal with a reference to create an error
voltage that controls a pulse-width modulator (PWM) circuit. The PWM then
produces an output signal at constant frequency and with a duty cycle that
varies according to the input signal. This controls the switching action of the
output power stage (H-bridge). A block diagram of the major components that
make up the amplifier is shown in Figure 3–4.

Figure 3–4.Class D Functional Diagram

Audio
Analog
Source

Ramp

Generator

Comparator

V

ERROR

The audio input signal (Vin) is applied to a comparator along with a triangle
wave created by the ramp generator (V
the audio input on the rising and falling ramps, the comparator sends an error
signal to the PWM control circuit. The PWM signal regulates the duty cycle of
the H-bridge circuit to provide V
in Figure 3–5.

Figure 3–5.Class D Input and Output Waveforms

V

PWM

Control

LPF

ramp

. Examples of these waveforms are shown

out

CONTROL

V

OUT

H-Bridge

Load

). When the triangle wave crosses

V

IN

V

RAMP

5 V

V

OUT

0 V

The triangle wave must be operating at a much higher frequency than the
highest frequency component of the input signal in order to get an accurate
representation at the amplifier output. The TP A005D02 EVM uses a 250 kHz
switching rate to sample the input, which is more than ten times higher than
the highest frequency component of the 20 Hz to 20kHz audio input range.

Details

3-5

The TPA005D02 Audio Power Amplifier Evaluation Module

The H-bridge circuit consists of DMOS power transistors for supplying the
heavy currents which are required by the load. These transistors operate in
either the cutoff or saturation regions rather than the linear region in which
class AB amplifiers operate. Switching and conduction losses are reduced
since the transistor is active for only a small part of the duty cycle, reducing the
power dissipated by the power transistors and allowing more power to be
delivered to the load. A low pass filter (LPF) then removes the high frequency
switching component from the output signal, leaving an amplified version of
the original input signal. The DMOS transistors are arranged in an H-bridge
(full bridge) configuration to allow BTL operation, which further enhances the
amplifier performance.

3.2.2.1 BTL Operation

In the bridge-tied load output mode, the two output lines of each channel
operate as mirror images of each other for increased power. The speaker load
is connected directly across OUT+ and OUT–, and neither line is connected
to ground. BTL operation provides many benefits, including quadruple the
output power of single-ended operation and no need for bulky output coupling
capacitors. For more information, see the TP A005D02 amplifier IC data sheet,
TI Literature Number SLOS205.

T o operate in the bridge-tied load output mode, the module output signal from
OUT+ must go 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, but also from the OUT– lines of any other amplifiers in
the system. The platform provides such isolated output lines from the amplifier
EVM sockets directly to separate left and right speaker connectors.

3-6

Details

3.2.3 EVM Design Considerations

Circuit design and layout plays a large role in the creation or reduction of

distortion in class D amplifiers, and the high frequency switching

characteristics of class D audio power amplifier output stages offer some

interesting design challenges over conventional class AB amplifiers.

The main goal of the design of this EVM is to offer the best performance with

the smallest components, without sacrificing performance. For this reason

surface mount technology (SMT) parts are used whenever possible. The

major design considerations are discussed below and refer to Figures 3–2 and

3–3 unless otherwise noted. The actual parts used in the EVM are listed in

Table 3–3.

The audio signal path is the most critical, so the discussion begins there.

3.2.3.1 Input Filter

The first consideration is the desired frequency bandwidth (BW). High-fidelity

audio requires a flat 20Hz to 20kHz bandwidth. The low frequency –3-dB point

is set using an ac coupling capacitor at the amplifier inputs (IC pins 4, 5, 44,

and 45) which creates a high-pass filter (HPF). The –3-dB point for a first-order

HPF is found using the equation

The TPA005D02 Audio Power Amplifier Evaluation Module

1

+

f

LO

(2pRC)

where R = 10 kΩ is the input resistance of the amplifier and C = 1 µF for the

value of capacitors C2, C3, C6, and C7. These values give a –3-dB point of

15.9 Hz—close to the desired –3-dB point of 20 Hz. Ceramic capacitors are

preferred over electrolytic for their small size, low equivalent series resistance

(ESR), low noise, and long life. The smallest ceramic SMT package currently

available is 0603, yet availability necessitates using an 0805 package.

Other considerations are stability over temperature, voltage rating, and cost.

A tradeoff exists between the size, temperature characteristics, rated voltage,

and capacitance value. For a given package size, for example, an increase in

the voltage rating means a decrease in capacitance. The same applies to

improved temperature stability.

Temperature stability has little impact on the input capacitors since they

primarily couple the ac input signal and are not expected to dissipate large

amounts of heat. The input voltage is low for the class D EVM (less than

0.5 Vrms), so the rated voltage can also be low. An 0805 SMT package with

a rated voltage of 5 V and Y5V temperature characteristics would be ideal for

this application. Availability and cost constraints, however , dictated the use of

the power supply bypass capacitors that were finally selected, which meet all

requirements and are rated at 16V. If better matching of the left and right

channels is needed or a harsh environment will be encountered, then a

capacitor with X7R temperature characteristics should be considered.

Details

3-7

The TPA005D02 Audio Power Amplifier Evaluation Module

3.2.3.2 Output Filter

Class D amplifiers require special filtering at the output to remove the
high-frequency switching component and accurately reconstruct the audio
signal. The output filter is a low-pass filter (LPF) which sets the high frequency
–3-dB point of the bandwidth. The major consideration here is how to choose
the components and set the desired –3-dB point.

Filter Design Goals

A second-order low-pass filter is used for the output filter. The Butterworth filter
is characterized by a flat response over the pass band and less attenuation
after the cutoff frequency. The order of the filter determines how many poles
exist that are at the same frequency, with each pole providing –20 dB per
decade of signal attenuation for a total of –40 dB per decade in this circuit. The
cutoff frequency (fc) can be determined using the equation

f

+

C

1

Ǹ

(2pLC

)

where L is the inductance and C is the equivalent capacitance. The values
used in the output filter are 15 µH for the inductor, and 0.22 µF and 1 µF
capacitors in parallel for an equivalent capacitance of 2.22 µF, setting the
cutoff frequency to 27.5 kHz. The main purpose of this filter is to reduce the
switching frequency to an acceptable level and not attenuate the audio band.
The 250 kHz amplifier output signal is then reduced by –40 dB to one percent
of its pre-filter value.

The considerations for inductor selection are inductance, continuous and peak
current ratings, dc series resistance, and the packaging. The inductance was
chosen based on common inductance and capacitance values, to be 15 µH.

Class D Output Filter Design Methodology

The output filter attenuates the high switching frequency. A second-order
Butterworth low-pass filter was chosen for its flat pass band, good phase
response, and low parts count (it requires only an inductor and a capacitor).
The normalized transfer for the Butterworth filter is

H(s)

+

s2)

1

Ǹ

2

s)1

The next step is to realize the circuit and develop a transfer function. The filter
for a single-ended application is shown in Figure 3–6.

Figure 3–6.Single-Ended Class D Output FIlter

I

L

L

3-8

+

V

I

–

I

O

+

R

V

L

C

L

O

–

Details

The TPA005D02 Audio Power Amplifier Evaluation Module

The transfer function is easily derived by using a voltage divider equation with

the load voltage being a parallel combination of R

and CL. This transfer

L

function is

1

1

RLC

LC

S)

L

L

1

LC

L

VO(s)

VI(s)

+

S2)

The next step is to set the terms of the circuit transfer function equal to the

terms of the normalized 2nd-order Butterworth low-pass filter and solve for L

and C

CL+

in terms of RL. This yields

L

1

Ǹ

2

R

L

L

+

2Ǹ

R

L

These values give a cut-off frequency at ω

that the components must be frequency scaled. To frequency scale, each

component is divided by ω

= 2 × π × f

0

Hertz):

CSE+

LSE+

ω0+2 p

1

Ǹ

2

RL

ω

0

Ǹ

R

2

L

w

o

f

c

Because the TP A005D02 is a bridged amplifier, this filter is needed at both the

positive and negative output. This means that R

filter, so for a bridged application, R

calculations. One capacitor can be used in place of the two capacitors in the

output filters if the capacitor is placed across R

to ground. This circuit is shown in Figure 3–7.

R

L

Figure 3–7.Low-Pass Filter for Bridged Application

I

O

+ VO –

+

–

L

BTL

V

I

= 1 radian/second, which means

0

(fc is the desired cut-off frequency in

c

must be split between each

L

must be divided by 2 in the component

L

instead of from each side of

L

R

C

L

BTL

+

V

I

–

Details

3-9

The TPA005D02 Audio Power Amplifier Evaluation Module

The component equations adjusted for bridged amplifiers are

C

L

BTL

BTL

+

Ǹ

+

Ǹ

2

2

2 ω

1

RL

R

L

0

T o find component values, let fc = 30 kHz, which yields ω0 = 188495.6 radians/
second. If a 4-Ω speaker is used, R
= 0.94 µF . Additional capacitors can be added from each side of RL to ground
to provide a high-frequency short to ground. These additional capacitors
should be approximately 10% of 2C
Figure 3–8 with the components rounded to standard values.

Figure 3–8.Resulting Bridged Output Filter

LOUTP or ROUTP

LOUTN or ROUTN

ω

0

15 µH

15 µH

= 4 Ω. This yields L

L

. The resulting output filter is shown in

BTL

0.22 µF
1 µF

0.22 µF

= 15 µH and C

BTL

BTL

4 Ω

Output Filter Components

The output inductors are key elements in the performance of the class D audio
amplifier system. It is important that these inductors have a high enough
current rating and a relatively constant inductance over frequency and
temperature. The current rating should be higher than the maximum current
expected to avoid magnetically saturating the inductor. When saturation
occurs, the inductor loses its functionality and looks like a short circuit to the
PWM signal, which increases the harmonic distortion considerably.

A shielded inductor may be required if the class D amplifier is placed in an EMI
sensitive system; however, the switching frequency is low for EMI
considerations and should not be an issue in most systems. The DC series
resistance of the inductor should be low to minimize losses due to power
dissipation in the inductor, which reduces the efficiency of the circuit.

Capacitors are important in attenuating the switching frequency and high
frequency noise, and in supplying some of the current to the load. It is best to
use capacitors with low equivalent-series-resistance (ESR). A low ESR
means that less power is dissipated in the capacitor as it shunts the
high-frequency signals. Ceramic (C24, C25, C26, and C27) and metal film
(C22 and C23) capacitors were selected because of their low ESR. Placing
these capacitors in parallel also parallels their ESR, effectively reducing the
overall ESR value. The voltage rating is also important, and, as a rule of thumb,
should be 2 to 3 times the maximum rms voltage expected to allow for high
peak voltages and transient spikes. These output filter capacitors should be
stable over temperature since large currents flow through them.

3-10

Details

3.2.3.3 Power Filtering

The TPA005D02 Audio Power Amplifier Evaluation Module

Power supply considerations include power supply decoupling and high
frequency bypass loops. Electrolytic capacitors are used for decoupling and
ceramic or mica capacitors are used for high frequency bypass applications.

Decoupling capacitors serve to smooth the input voltage and assist the
amplifier by providing current when needed. These capacitors may shunt
relatively large ripple currents to ground and must have a low equivalent series
resistance (ESR) to reduce power and heat dissipation in the device. The ESR
combines all losses, both series and parallel, in a capacitor at a given
frequency in order to reduce the equivalent circuit to a simple RC series
connection, valid only for low frequencies (less than 1 MHz).

Other considerations are the voltage rating, capacitance, physical size, and
the specific type of capacitor. The voltage rating should exceed the maximum
supply voltage expected in order to handle voltage surges and spikes without
being damaged. The capacitance is then important, as it specifies the amount
of energy that can be stored in the capacitor. Once the voltage rating and
capacitance are known, the size can be determined.

Since the focus was to get the largest capacitance possible yet keep the size
to a minimum, tantalum capacitors, instead of aluminum electrolytic
capacitors, were chosen. Tantalum capacitors provide a higher capacitance
value in a smaller package and have lower ESR values than aluminum
electrolytic capacitors. SMT packages further reduce the inductance
associated with lead lengths. All of these considerations led to the selection
of a 220 µF SMT tantalum capacitor as the primary decoupling capacitor.

The high frequency bypass capacitors are usually small in size, limited by the
size of the capacitance to approximately 10 µF or less. Ceramic capacitors
have extremely low ESR and dissipate very little power. Lower ESR means a
lower net impedance at higher frequencies, which is more suitable for filtering
the higher frequency components of the power supply, especially voltage
spikes. Bypass capacitors should be placed as close as possible to the IC
power input pins and also as close to the IC power ground pins as possible.
The idea is to form the smallest possible loop, or path, over which the high
frequency signals can travel, and minimize the impedance. A short path with
a high impedance defeats the purpose.

The power pins (VDD) were placed at the top and bottom of the IC package,
and the power traces and filtering capacitors were arranged to balance the left
and right channels of the IC. A trace along the bottom of the board links the
V

pins for EVM stand-alone operation and supplies power to the right and

DD

left channels in parallel. This places the capacitors and their ESR in parallel,
increasing the overall capacitance seen by the power source while greatly
reducing the ESR.

Details

3-1 1

The TPA005D02 Audio Power Amplifier Evaluation Module

3.2.3.4 Ground Plane

Experimentation with several types of ground planes has shown that a solid
ground plane works as well as methods that split the analog and power ground
planes when good layout practices are followed. This allows a much simpler
design that requires less time and is less prone to layout errors. The success
of the solid ground plane is partially due to the TPA005D02 IC, which allows
the designer to keep the input and output sections of the chip separated,
reducing the chance that high- and mid-frequency return currents will make a
path to the analog input section of the chip.

The traces for the analog circuit grounds are extremely short and are
connected to the ground immediately under the chip through vias, while the
power circuit grounds are connected to the ground plane slightly further out
from the chip and closer to the signal outputs and power inputs. The large
current traces of the output are then shielded from the input circuit by the
ground plane.

The solid ground plane has low resistance compared with the narrow paths to
pins and vias that are attached. If a voltage spike or current spike hits the
ground plane, the entire plane shifts up or down, unlike a split plane, which has
inductance between the halves that dampens the noise and can cause uneven
voltage potentials to exist.

3.2.3.5 Compensation, Ramp Generator, and Charge Pump Capacitors

The components (C19, C5, C4 and C8) for these circuits are critical to the
operation of the TP A005D02 amplifier. The capacitance at these nodes must
be close to the specified value and maintain this value over EVM temperature
extremes. Ceramic capacitors with X7R temperature characteristics should be
used for their low ESR and their stability over a wide temperature range. Tight
tolerances are needed, especially for RCOMP (C4) and LCOMP (C8), which
need to track closely for good left and right channel matching. A high voltage
rating is not needed (15 V would work), yet 50 V is one of the lowest ratings
for the size and type of capacitor selected.

Ramp generator capacitor C5 does not need the tight capacitance value
tolerance that C4 and C8 require; however, capacitance stability over
temperature change is important.

Charge pump capacitor C19 has the same requirements as the ramp
generator capacitor (C5), though the size is much larger and the necessary
voltage rating due to the charge tripling is increased, making the part
somewhat less readily available.

3-12

Details

3.2.3.6 Control and Indicator Circuits

The shutdown circuit, the mute circuit, and the fault indicator circuit are all
low-current circuits and are not as critical in the layout design as the circuits
mentioned previously.

Shutdown

The shutdown control (IC pin 1) is activated by a logic low. Shutdown limits the
supply current of the TPA005D02 to 400 µA to conserve power in low power
applications.

The shutdown circuit (IC pin 1) consists of D1, Q1, R1, R2, R3, R4, C1, and
S2, a relatively large number of components. Since space and power
consumption are to be minimized, these components need to be small,
low-power devices. Switch S2 is actually the component that sends the device
into shutdown mode—there is no shutdown control input pin on the EVM. The
remaining components form a delay circuit that eliminates noise created by the
discharge of energy stored in the output filter when the amplifier IC is initially
placed in shutdown.

The PNP transistor needs to be biased so that it is operational from at least

4.5 V to 5.5 V. Zener diode D1 and resistors R1, R2, and R3 set the bias for
the transistor so that it is kept in its linear region and minimizes the supply
current used by this circuit. The maximum zener voltage Vz is then calculated
to be

The TPA005D02 Audio Power Amplifier Evaluation Module

Vz = V

DD(min)–VBE(min)

= 4.5V–0.6V = 3.9V

Zener diode D1 was selected based on Vz and the current required for
operation. Resistor R1 limits the current through the diode, while R2 also helps
limit the base current and isolate the bootstrap capacitor C1. Resistor R3 limits
the collector current during normal operation, and R4 limits the current flowing
to ground when switch S2 is closed.

Mute

The mute control (IC pin 2) is activated by a logic low, in which case the
amplifier low-side output transistors are turned on, shorting the load to ground.
The main consideration is to minimize the current used. A 100-kΩ pullup
resistor is used to limit the current to microamps and minimize the power
dissipated in the resistor, allowing a smaller surface-mount package to be
used.

Details

3-13

The TPA005D02 Audio Power Amplifier Evaluation Module

Fault Indicator

The TP A005D02 IC has two fault indicator pins (IC pins 41 and 42) to indicate
an under-voltage condition or a thermal fault. When the device is operating
normally, both pins are pulled up to the supply voltage through R6/D2 and
R7/D3. If the power supply voltage drops too low, the charge pump voltage
drops below the operational threshold and the low-side transistors short to
ground. When this occurs, IC pin 41 goes to ground, creating a voltage drop
across the LED, causing it to illuminate. The LED remains lit until the fault
circuit is reset by cycling the power or operating the shutdown or mute switch.

Table 3–1. TPA005D02 Class D EVM Fault Indicator Table

LED 1 LED 2 Fault Description

OFF OFF No faults—device is operating normally
OFF ON Under-voltage condition

ON ON Thermal fault

The fault indicator circuits (IC pins 41 and 42) are designed to minimize current
consumption and yet have an LED that is clearly visible when illuminated. The
LED should be as small as possible, have a wide viewing angle, and be bright
enough to clearly see while using minimal current. The LEDs selected require
a 2.1-V drop when activated, and approximately 3 mA of current to be fully
illuminated. The current-limit resistance needed is then calculated:

+

DD

R

d

+

967

I

d

W

–V

V

A 1-kΩ resistor was used for R6 and R7. Tests demonstrate that the LEDs
selected operate as expected and are clearly visible when the fault circuit is
activated.

3-14

Details

The TPA005D02 Audio Power Amplifier Evaluation Module

3.2.4 Efficiency of Class D vs. Linear Operation

Amplifier efficiency is defined as the ratio of output power delivered to the load
to power drawn from the supply . In the efficiency equation below, P
across the load and P

Efficiency+h

A high-efficiency amplifier has a number of advantages over one with lower
efficiency. One of these advantages is a lower power requirement for a given
output, which translates into less waste heat that must be removed from the
device, smaller power supply required, and increased battery life.

Audio power amplifier systems have traditionally used linear amplifiers, which
are well known for being inefficient. Class D amplifiers were developed as a
means to increase the efficiency of audio power amplifier systems.

A linear amplifier is designed to act as a variable resistor network between the
power supply and the load. The transistors operate in their linear region and
voltage that is dropped across the transistors (in their role as variable
resistors) is lost as heat, particularly in the output transistors.

is the supply power.

SUP

P

L

+

P

SUP

is power

L

The output transistors of a class D amplifier switch from full OFF to full ON
(saturated) and then back again, spending very little time in the linear region
in between. As a result, very little power is lost to heat because the transistors
are not operated in their linear region. If the transistors have a low ON
resistance, little voltage is dropped across them, further reducing losses. The
ideal class D amplifier is 100% efficient, which assumes that both the ON
resistance (R

DS(ON)

) and the switching times of the output transistors are zero.

3.2.4.1 The Ideal Class D Amplifier

To illustrate how the output transistors of a class D amplifier operate, a
half-bridge application is examined first (Figure 3–9).

Figure 3–9.Half-Bridge Class D Output Stage

V

DD

M1

V

A

M2

I

L

L

I

OUT

+

V

R

C

L

C

OUT

L

–

Details

3-15

The TPA005D02 Audio Power Amplifier Evaluation Module

Figures 3–10 and 3–11 show the currents and voltages of the half-bridge
circuit. When transistor M1 is on and M2 is off, the inductor current is
approximately equal to the supply current. When M2 switches on and M1
switches off, the supply current drops to zero, but the inductor keeps the
inductor current from dropping. The additional inductor current is flowing
through M2 from ground. This means that VA (the voltage at the drain of M2,
as shown in Figure 3–9) transitions between the supply voltage and slightly
below ground. The inductor and capacitor form a low-pass filter, which makes
the output current equal to the average of the inductor current. The low pass
filter averages V

, which makes V

A

by the duty cycle.

Control logic is used to adjust the output power, and both transistors are never
on at the same time. If the output voltage is rising, M1 is on for a longer period
of time than M2.

Figure 3–10. Class D Currents

equal to the supply voltage multiplied

OUT

Current

0

M1 on
M2 off

Figure 3–11. Class D Voltages

Voltage

M1 off
M2 on

M1 on
M2 off

Time

Inductor Current

Output Current

Supply Current

V

V

A

V

OUT

DD

3-16

0

M1 on
M2 off

M1 off
M2 on

M1 on
M2 off

Time

Details

The TPA005D02 Audio Power Amplifier Evaluation Module

Given these plots, the efficiency of the class D device can be calculated and
compared to an ideal linear amplifier device. In the derivation below, a sine
wave of peak voltage (V

) is the output from an ideal class D and linear

P

amplifier and the efficiency is calculated.

CLASS D LINEAR

V

AverageǒI

PL+

P

P

SUP

L(rms)

SUP

+

VL

+

VDD

V

+

Ǹ

DD

I

DD

Efficiency+h

P

2

Ǔ

+

L

+

L(rms)

I

V

AverageǒI

I

L(rms)

V

DD

P

L

P

SUP

V

DD

DD

V

L(rms)

Ǔ

L(rms)

V

L(rms)

V

PL+

AverageǒI

P

+

SUP

Efficiency

Efficiency

V

Efficiency+h+1 Efficiency

V

+

Ǹ

L(rms)

R

L

DD

VDD

+h+

+h+

+h+

P

2

2

+

Ǔ

+

2

V

P

2R

L

V

2

P

p

R

L

AverageǒI

P

L

P

SUP

VDD

p

4

V

V

DD

P

DD

V

DDVP

Ǔ

+

R

L

2

V

P

2R

L

V

2

P

p

R

L

2

p

In the ideal efficiency equations, assume that VP = VDD, which is the maximum
sine wave magnitude without clipping. Then, the highest efficiency that a linear
amplifier can have without clipping is 78.5%. A class D amplifier, however , can
ideally have an efficiency of 100% at all power levels.

The derivation above applies to an H-bridge as well as a half-bridge. An
H-bridge requires approximately twice the supply current but only requires half
the supply voltage to achieve the same output power—factors that cancel in
the efficiency calculation. The H-bridge circuit is shown in Figure 3–12.

Figure 3–12. H-Bridge Class D Output Stage

V

DD

M1

V

A

M2

I

I

L

OUT

L

C

L

V

+

OUT

R

L

V

DD

–

C

L

M4

L

M3

Details

3-17

The TPA005D02 Audio Power Amplifier Evaluation Module

3.2.4.2 Losses in a Real-World Class D Amplifier

Losses make class D amplifiers nonideal, and reduce the efficiency below
100%. These losses are due to the output transistors having a nonzero
R

, and rise and fall times that are greater than zero.

DS(on)

The loss due to a nonzero R

is called conduction loss, and is the power

DS(on)

lost in the output transistors at nonswitching times, when the transistor is ON
(saturated). Any R

above 0 Ω causes conduction loss. Figure 3–13

DS(on)

shows an H-bridge output circuit simplified for conduction loss analysis and
can be used to determine new efficiencies with conduction losses included.

Figure 3–13. Output Transistor Simplification for Conduction Loss Calculation

VDD = 5 V

R

DS(on)

R

DS(off)

The power supplied, P
plus the power lost in the transistors, assuming that there are always two
transistors on.

0.31 Ω

5 MΩ

SUP

5 MΩ

R

L

4 Ω

0.31 Ω

, is determined to be the power output to the load

R

DS(off)

R

DS(on)

Efficiency

Efficiency

Efficiency

Efficiency

Efficiency

+h+

+h+

+h+

+h+

+h+

P

L

P

SUP

2

R

I

L

I22R

2R

DS(on)

DS(on)

)

I2R

L

R

L

)

R

L

95%ǒat all output levels R

87%ǒat all output levels R

DS(on)

DS(on)

+

0.1, RL+

+

0.31, RL+

Ǔ

4

Ǔ

4

3-18

Details

Losses due to rise and fall times are called switching losses. A plot of the
output, showing switching losses, is shown in Figure 3–14.

Figure 3–14. Output Switching Losses

The TPA005D02 Audio Power Amplifier Evaluation Module

1

f

SW

t

SWon

+

Rise and fall times are greater than zero for several reasons. One is that the
output transistors cannot switch instantaneously because (assuming a
MOSFET) the channel from drain to source requires a specific period of time
to form. Another is that transistor gate-source capacitance and parasitic
resistance in traces form RC time constants that also increase rise and fall
times.

The switching power loss formula below with the following values (V
t

= 50 ns, fSW = 250 kHz, R

SW

loss of 4.4 mW at all output powers.

1

tSW

2

P

+

SW

Switching losses are constant at all output power levels, which means that
switching losses can be ignored at high power levels in most cases. At low
power levels, however, switching losses must be taken into account when
calculating efficiency.

3.2.4.3 Class D Effect on Power Supply

f

SW

2R

t

SWoff

ǒ

DS(on)

=

DS(on)

VDD2R
RL)

2R

t

SW

= 310 mΩ, R

2

DS(on)

Ǔ

DS(on)

= 5V ,

DD

= 4 Ω) yields a switching power

L

Efficiency calculations are an important factor for proper power supply design
in amplifier systems. Table 3–2 shows class D efficiency at a range of output
power levels (per channel) with a 1-kHz sine wave input. The maximum power
supply draw from a stereo 1-W per channel audio system with 8-Ω loads and
a 5-V supply is almost 2.7 W. A similar linear amplifier such as the TPA0202
has a maximum draw of 3.25 W under the same circumstances.

Table 3–2.Efficiency vs Output Power in 5-V 8-Ω H-Bridge Systems

Output Power (W) Efficiency (%) Peak Voltage (V) Internal Dissipation (W)

0.25 63.4 2 0.145

0.5 73 2.83 0.183

0.75 77.1 3.46 0.222
1 79.3 4 0.314

1.25 80.6 4.47

†

High peak voltages cause the THD to increase

†

Details

0.3

3-19

The TPA005D02 Audio Power Amplifier Evaluation Module

There is a minor power supply savings with a class D amplifier versus a linear
amplifier when amplifying sine waves. The difference is much larger when the
amplifier is used strictly for music. This is because music has much lower RMS
output power levels, given the same peak output power (Figure 3–15); and
although linear devices are relatively efficient at high RMS output levels, they
are very inefficient at mid-to-low RMS power levels. The standard method of
comparing the peak power to RMS power for a given signal is crest factor,
whose equation is shown below. The lower RMS power for a set peak power
results in a higher crest factor

P

Crest Factor

+

10 log

PK

P

rms

Figure 3–15. Audio Signal Showing Peak and RMS Power

Power

Time

P

P

PK

RMS

Figure 3–16 is a comparison of a 5-V class D amplifier to a similar linear
amplifier playing music that has a 13.76-dB crest factor. From the plot, the
power supply draw from a stereo amplifier that is playing music with a 13.76
dB crest factor is 1.02 W, while a class D amplifier draws 420 mW under the
same conditions. This means that just under 2.5 times the power supply is
required for a linear amplifier over a class D amplifier.

Figure 3–16. Audio Signal Showing Peak and RMS Power (with Music Applied)

POWER SUPPLIED

vs

PEAK OUTPUT VOLTAGE AND PEAK OUTPUT POWER

600

500

400

TPA0202

300

Power Supplied (mW)

200

TPA005D02

3-20

100

0

1 1.5 2 2.5

0.25 0.56 1 1.56 4 5.062.25

3.5

3.06

4 4.53

Peak Output Voltage (V)
Peak Output Power (W)

Details

The TP A005D02 Audio Power Amplifier Evaluation Module

3.2.4.4 Class D Effect on Battery Life

Battery operations for class D amplifiers versus linear amplifiers have similar
power supply savings. The essential contributing factor to longer battery life
is lower RMS supply current. Figure 3–17 compares the TPA005D02 supply
current to the supply current of the TP A0202, a 2-W linear device, while playing
music at different peak voltage levels.

Figure 3–17. Supply Current vs Peak Output Voltage of TPA005D02 vs TPA0202 with
Music Input

SUPPLY CURRENTS

vs

PEAK OUTPUT VOLTAGE AND PEAK OUTPUT POWER

400

350

300

250

200

TPA0202

150

Supply Current (mA rms)

100

50

0

1 1.5 2 2.5

0.25 0.56 1 1.56 42.25

This plot shows that a linear amplifier has approximately three times more
current draw at normal listening levels than a class D amplifier. Thus, a class
D amplifier has approximately three times longer battery life at normal listening
levels. If there is other circuitry in the system drawing supply current, that must
also be taken into account when estimating battery life savings.

TPA005D02

3.5

3.06

Peak Output Voltage (V)

43

Peak Output Power (W)

Details

3-21

Using The TPA005D02 Class D EVM With the Plug-N-Play Platform

3.3 Using The TPA005D02 Class D EVM With the Plug-N-Play Platform

The TPA005D02 Class D Stereo Audio Amplifier Evaluation Module was
designed to be used with the TI Plug-N-Play Audio Amplifier Evaluation
Platform. It simply plugs into socket U2.

The following paragraphs provide additional details for using the TP A005D02
class D EVM 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

3.3.1.2 EVM Removal

1) Remove all power from the evaluation platform.

2) Locate socket U2 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.

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) Change to the opposite side of the module and use the tool to pry that side
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.

3-22

5) Lift the EVM off of the platform.

Details

3.3.2 Module Switches

The TPA005D02 Class D Stereo Audio Amplifier Evaluation Module is
equipped with two pushbutton switches that allow the module shutdown and
mute functions to be manually activated.

3.3.2.1 S1 — Shutdown

To have the module amplifier IC enter the shutdown mode, press the
Shutdown switch (S1) on the module. S1 connects the amplifier IC
SHUTDOWN
not controlled by a control input to the module—only by switch S1.

The shutdown mode reduces the amplifier IC current consumption to
approximately 400 µA compared to approximately 10 mA in the mute mode.

3.3.2.2 S2 — Mute Switch

Pushbutton switch S2 on the TP A005D02 class D EVM allows manual muting
of the amplifier IC. S2 connects the amplifier IC MUTE
the output. The EVM Mute control input pin allows control of this function by
the platform or other external circuit.

Using The TPA005D02 Class D EVM With the Plug-N-Play Platform

pin to ground, forcing it into a low-power state. This function is

pin to ground, muting

Details

3-23

Using The TPA005D02 Class D EVM With the Plug-N-Play Platform

3.3.3 Signal Routing

Signal flow on the platform is controlled by two signal routing switches, as
shown in Figure 3–18.

Figure 3–18. Platform Signal Routing and Outputs

Off

R

Audio

Input

L

U1

Signal

Conditioning

S2

On

U2

TPA005D02

Amplifier EVM

U5

Stereo

Headphone

Amplifier

L

+

GND

R

L

R

L

–

J7, J8, J9

Speaker
Outputs

–
+

+
–

Headphone

Output

–
+

J10

R

L

U2–U4

R

S3

U5

3.3.3.1 Signal Conditioning

The audio signal from input jacks can be applied to the signal conditioning
socket (U1) if an EVM is installed there, or socket U1 can be bypassed and the
audio input signal applied directly to the inputs of the TPA005D02 class D
EVM.

-

Platform switch S2 selects signal conditioning or bypasses it.

3.3.3.2 Headphone Output Jack

Switch S3 is the source select for the stereo headphone output jack, J10. The
headphone jack is capacitively coupled (via 470 µF electrolytics) and can
output either the signal from the headphone amplifier in socket U5, or the
signal from the power amplifier installed in socket U2, as determined by the
setting of headphone source select switch S3.

-

The TP A005D02 is designed to drive BTL loads only , S3 MUST AL W A YS
BE SET TO THE

installed on the platform.

U5

POSITION when the TPA005D02 class D EVM is

3-24

Details

Using The TPA005D02 Class D EVM With the Plug-N-Play Platform

3.3.4 Mute

The TP A005D02 class D EVM is equipped with a mute control input pin. When
this input is tied to GND, the TP A005D02 amplifier IC on the module enters the
mute mode and dissipates very little power. When the EVM control input is tied
to V

In typical applications, as often found in notebook computers, portable audio
products, and such, the internal speakers mute when headphones are
plugged into the headphone jack, or internal speakers mute when external
speakers are connected. In applications using separate speaker and
headphone amplifiers, the one not being used can be muted to conserve
power.

3.3.4.1 Headphone Jack Control Signals

The platform headphone output jack (J10) contains an internal switch that
changes the state of a pair of control lines when a plug is inserted (Figure
3–19). Each control line is pulled down by a 1-kΩ resistor to ground (R4 and
R5). The switch in the headphone jack pulls one line or the other up to V
through a 240-Ω resistor (R3) depending on whether a plug is inserted in J10
or not.

or allowed to float, amplifier operation resumes.

DD

DD

Figure 3–19. Mute/Mode and Polarity Control

V

DD

R3
240 Ω

J10

Headphone

Jack

R4
1 kΩ

3.3.4.2 Mute/Mode Select (JP6)

A 3-pin jumper header (JP6) on the platform, functioning as an SPDT switch,
routes the control signal from the headphone jack to either the mute control
input pin or the mode control input pin of the evaluation module.

J

T o mute the TP A005D02 class D EVM using the control signal from the
platform headphone jack, jumper JP6 to

J

To isolate the TPA005D02 class D EVM from the headphone jack
switch (since the TPA005D02 class D EVM has no mode control
input), jumper JP6 to

3.3.4.3 Mute/Mode Polarity Select (JP8)

R5
1 kΩ

MODE.

Polarity

JP8 JP6

Lo

Hi

SPK

(U2–U4)

Mode

Mute

MUTE.

U2

Power

Amplifier

A second 3-pin jumper header (JP8) on the platform selects the control signal
polarity by connecting either the active-high or the active-low line from the
headphone jack to jumper JP6.

-

To mute the TPA005D02 class D EVM
headphone jack, jumper JP8 to

Lo

when

a plug is inserted into the

(the Hi position is NOT recommended).

Details

3-25

Power Requirements

3.3.5 Power Requirements

The TP A005D02 Class D Stereo Audio Power Amplifier Evaluation Module is
designed to operate from a supply voltage between 4.5 V and 5.5 V . For best
performance (highest output power with lowest distortion), the module should
be operated on at least 5 V.

The TI Plug-N-Play Audio Amplifier Evaluation Platform with a voltage
regulator EVM installed on it can provide a regulated V
variety of unregulated V
12 V , including an onboard 9-V battery . Or, an external regulated power source
can be used to supply V
evaluation module installed on it.

Although the TP A005D02 amplifier IC draws approximately 2 A from the power
supply during continuous full power output, peak current draw can be as high
as 5 A. Any power supply connected to the platform should be capable of
providing 5 A of current to avoid clipping of the output signal during peaks.
Current consumption driving speakers at normal listening levels is typically

0.5 A or less.

The platform is equipped with overvoltage and reverse-polarity supply voltage
input protection in the form of fused crowbar circuits.

supply from a wide

DD

voltage inputs between approximately 5.5 V and

CC

voltage to the platform and the TPA005D02

DD

-

VDD voltage applied to platform screw terminals J6

MUST NOT

the absolute maximum rating for the TP A005D02 amplifier IC installed on
the evaluation module (5.5 V) or damage to the IC may result. In no case
should V

voltage of the incorrect polarity or in excess of 6.1 V be applied

DD

to screw terminals J6 of the platform, or the power protection circuit on the

line will trip.

V

DD

-

VCC voltage applied to the platform

MUST NOT

exceed the maximum
voltage input specified for the voltage regulator module installed in socket
U6 (12 V for the SLVP097), or damage to the voltage regulator module
may result. In no case should V
15 V, or the overvoltage protection circuit on the V

voltage applied to the platform exceed

CC

bus will trip.

CC

exceed

3-26

Details

3.3.6 Inputs and Outputs

The TI Plug-N-Play Audio Amplifier Evaluation Platform is equipped with
several standard conectors for audio inputs and outputs.

3.3.6.1 Inputs

In most cases, audio signals enter the platform through either a pair of RCA
phono jacks (J3 and J5) or a miniature (1/8″) stereo phone jack (J4). Certain
signal conditioning and amplifier EVMs, however, may have additional signal
input connectors mounted on the module circuit board.

The platform audio signal input jacks (J3, J4, and J5) are of the closed-circuit
type, grounding the signal input lines when no plugs are inserted.

3.3.6.2 Outputs

Amplified audio output signals leave the platform through left and right RCA
phono jacks (J7 and J9), left and right pairs of compression connectors for
stripped speaker wires (J8), and optionally , through a miniature (1/8″ ) stereo
phone jack (J10), for headphones.

The audio output lines from the power amplifiers are separate all the way to
the edge of the platform (output jacks J7, J8, and J9)—the OUT– lines from
the power amplifier sockets are not tied to each other or to platform ground.
This allows the TPA005D02 power amplifier EVM to operate in the
highly-efficient bridge-tied load configuration when driving speakers.

Inputs and Outputs

The headphone jack (J10) is capacitively coupled to source select switch S3,
which connects J10 to the output lines of either the headphone amplifier
socket or the power amplifier sockets (Figure 3–20). Since the TPA005D02
class D EVM can drive only BTL outputs, S3 MUST ALW A YS BE SET TO THE

U5

POSITION.

Do not drive the module inputs unless speaker loads are connected to the
module outputs or the TPA005D02 amplifier IC will go into thermal shutdown.

Figure 3–20. Typical Headphone Plug

Left Right GND

Details

3-27

Using The TPA005D02 Class D EVM Stand-Alone

3.4 Using The TPA005D02 Class D EVM Stand-Alone

Using the TPA005D02 Class D Stereo Audio Power Amplifier Evaluation
Module stand-alone is much the same as using it with the platform. The same

4.5-V to 5.5-V power supply range and the isolated OUT+ and OUT– lines for
BTL operation requirement exists.

Power can be connected to either V

pin on the module. The audio input

DD

signal should be connected to the RIN+/RIN– and LIN+/LIN– module pins for
differential signals as shown below . Single-ended input signals are applied to
RIN+ and LIN+, while RIN– and LIN– are connected to ground.

Note that the mute signal applied to the EVM mute pin must be able to supply
enough current to overcome the pullup resistor on the module (100 kΩ).

Do not drive the module inputs unless speaker loads are connected to the
module outputs or the TPA005D02 amplifier IC will go into thermal shutdown.

3.4.1 TPA005D02 Class D EVM Connected for BTL Output

Figure 3–21. TPA005D02 Class D EVM Connected for Stereo BTL Output

5 V

Audio

Input

(Right)

Audio

Input

(Left)

GND
RIN+
RIN–

Shutdown
C1

R2
R1

Q1

LIN–
LIN+

GND

Mute

T exas Instruments

R6 R7

1998

C4
C2
C3

C5

R3

R4
R5

D1

S1

SLOP223

C8

S2

C6
C7

D2

1

C10

VDD

GND

C19

C20

L1

C14

L2

C21

L3

U1

L4

GND

D3

+

C12

C13

C9

C17

C15

+

C11

VDD

TPA005D02 EVM Board Rev. A

C24

C23

C25

C26

C22

C27

Rout+

Rout–

Mute

Lout–

Lout+

Right

External Mute

Control

(active low)

Left

3-28

Details

TP A005D02 Audio Power Amplifier Evaluation Module Parts List

3.5 TPA005D02 Audio Power Amplifier Evaluation Module Parts List

Table 3–3.TPA005D02 Class D EVM Parts List

Reference Description Size

C1, C2, C3, C6
C7, C9, C12, C13,
C16, C17, C18, C19

C4, C5, C8 Capacitor, Ceramic, 470 pF,

C20, C21 Capacitor, Ceramic, 0.047 µF,

C10, C11 Capacitor, Ceramic, 10 µF,

C14, C15 Capacitor,Tantalum, 220 µF,

C24, C25, C26, C27 Capacitor, Ceramic, 0.22 µF,

C22, C23 Capacitor, Metal Film, 1 µF,

D2, D3 LED, SM, Green, 25 mcd,

L1, L2, L3, L4 Inductor, 15 µH, 3.1 A rms,

Q1 Transistor, PNP, 60 V, 200 mA SOT-23 1 Zetex

R1, R3 Resistor, SMD, MF, 20 kΩ,

R2, R6, R7 Resistor, SMD, MF, 1 kΩ,

R4, R5 Resistor, SMD, MF, 100 kΩ, 1/16

S1, S2 Switch, Momentary, PB, 12 VDC,

U1 IC, Audio amplifier, class D,

D1 Diode, Zener, SMT, 3.9 V,

Capacitor, Ceramic, 1 µF,
16 V, Y5V, +80% –20%

50 V, X7R, 10%

50 V, X7R, 10%

16 V, Y5V, +80%–20%

10 V, 20%

25 V, X7R, 10%

50 V, ±5%, leaded

2.1 V, 120 deg

0.060 Ω

1/16 W, 5%

1/16 W, 5%

W, 5%

50 mA

5 W, 48 pin, DCA pkg

500 mW, 50 µA, 1N4686

0805 12 muRata

0603 3 muRata

0805 2 muRata

1210 2 muRata

Case E 2 AVX

0603 4 muRata

0.287 × 0.315 × 0.197 2 Panasonic

0.134 × 0.11 × 0.071 2 Lumex

0.51 × 0.37 × 0.30 4 Coilcraft

0603 2 Vishay/Dale

0603 3 Vishay/Dale

0603 2 Vishay/Dale

0.291 × 0.138 × 0.134 2 Panasonic

TSSOP48 1 TI

SOD-123 1 Motorola

EVM

Qty.

Manufacturer/

Part Number

GRM40Y5V105Z16

GRM39X7R471K50

GRM40X7R473K50

GRM235Y5V106Z16

TPSE227M010

GRM39X7R224K10

ECQ-V1H105JI

SML-LX2832GC-TR

DO3316P-153

FMMT3906CT-ND

CRCW0603203J

CRCW0603102J

CRCW0603104J

EVQ-PJS04K

TPA005D02DCA

MMSZ4686T1

Details

3-29

TPA005D02 Class D EVM Measured Characteristics

3.6 TPA005D02 Class D EVM Measured Characteristics

The TP A005D02 Class D Stereo Audio Power Amplifier EVM was tested using
an Audio Precision 2322, a 5-V regulated DC power supply , the TI PNP Audio
Power Amplifier Evaluation Platform set up as described in Chapter 2, and 4-W
speaker loads. The results are shown in Figures 3–22 through 3–25. The
TPA005D02 class D EVM exhibits slightly less harmonic distortion at high
power levels when used in the stand-alone mode.

The EVM has a flat response over the audio frequency band, as shown in
Figure 3–22. Both channels track closely; however, the response will change
slightly with the tolerance of the filter components. The lower and upper
frequency corners can be adjusted to extend frequency response as
described in sections 3.2.3.1 and 3.2.3.2.

Figure 3–22. Frequency Response

VOLTAGE AMPLIFICATION

vs

27
26

25

24

VDD = 5 V

RL = 4Ω

FREQUENCY

Left Channel

23
22

21
20

Voltage Amplification – dB

19

18

17
16

10 20 100 1k

f – Frequency – Hz

Right Channel

10k 20k

3-30

Details

Total harmonic distortion plus noise (THD+N) versus output power is shown
in Figure 3–23. A lower power levels (less than 40 mW), most of the distortion
is contributed by the class D amplifier device. Distortion at mid and high power
levels (40 mW to 1.9 W) is a function of the output filter components,
particularly the inductors.

A slight increase in supply voltage over 5 V substantially reduces the harmonic
distortion at power levels above 500 mW.

Figure 3–23. Distortion versus Output Power

TOTAL HARMONIC DISTORTION PLUS NOISE

10

VDD = 5 V

RL = 4Ω

5

2

1

TPA005D02 Class D EVM Measured Characteristics

vs

OUTPUT POWER

0.5

0.2

0.1

0.05

THD+N – Total Harmonic Distortion Plus Noise – (%)

0.03

0.02

0.01 0.05 0.1 0.2 0.5 1

20 KHz

Po – Output Power – W

1 KHz

100 Hz

2

Details

3-31

TPA005D02 Class D EVM Measured Characteristics

THD+N versus frequency is shown in Figure 3–24, and correlates with the data
shown in Figure 3–23. The rise in distortion at higher frequencies is due
primarily to the increase in crosstalk with frequency (Figure 3–25). The
crosstalk was measured at full output power, which is the worst-case scenario.
Crosstalk may be reduced by using shielded inductors in the output filter.

Figure 3–24. Distortion versus Frequency

TOTAL HARMONIC DISTORTION PLUS NOISE

10

VDD = 5 V

RL = 4Ω

5

2

1

vs

FREQUENCY

0.5

0.2

THD+N – Total Harmonic Distortion Plus Noise – (%)

0.1
20 100 1k

Figure 3–25. Crosstalk versus Frequency

–30

VDD = 5 V

–35

–40
–45
–50
–55
–60
–65

Crosstalk – dB

–70
–75
–80

–85

–90

RL = 4Ω

PO = 2 W

20 100 1k

1 W

1/2 W

10k 20k

CROSSTALK

vs

FREQUENCY

L to R

R to L

10k 20k

f – Frequency – Hz

3-32

Details

3.7 TPA005D02 Class D EVM PCB Layers

The following illustrations depict the TPA005D02 class D EVM PCB layers.
These drawings are not to scale. Gerber plots can be obtained from any TI
Sales Office.

Figure 3–26. TPA005D02 Class D EVM Silkscreen

TPA005D02 Class D EVM PCB Layers

GND

RIN+
RIN–

Shutdown
C1

R2

R1

Q1
LIN–

LIN+
GND

Mute

T exas Instruments

R6 R7

1998

C4
C2
C3

C5

R3

R4
R5

D1

S1

SLOP223

C8

S2

D2

C10

1

C6

C7

VDD

D3

C16

+

C12

C13

C9

C17

C15

+

C11

VDD

TPA005D02 EVM Board Rev. A

Figure 3–27. TPA005D02 Class D EVM Top Layer

C18

C19

GND

C20

U1

GND

C14

L1

L2

C21

L3

L4

C24

C25

C22

C23

C26

C27

Rout+

Rout–

Mute

Lout–

Lout+

Details

3-33

TPA005D02 Class D EVM PCB Layers

Figure 3–28. TPA005D02 Class D EVM 2nd Layer

Figure 3–29. TPA005D02 Class D EVM 3rd Layer

3-34

Details

Figure 3–30. TPA005D02 Class D EVM Bottom Layer

TPA005D02 Class D EVM PCB Layers

Details

3-35

3-36

Details