Texas Instruments TLV320DAC26EVM User manual

TLV320DAC26EVM
DAC Evaluation Module
June 2004 Data Acquisition Products
User’s Guide
SLAU136

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Mailing Address: Texas Instruments
Post Office Box 655303 Dallas, Texas 75265
Copyright 2004, Texas Instruments Incorporated

EVM IMPORTANT NOTICE
Texas Instruments (TI) provides the enclosed product(s) under the following conditions:
This evaluation kit being sold by TI is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION
PURPOSES ONLY and is not considered by TI to be fit for commercial use. As such, the goods being provided
may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective
considerations, including product safety measures typically found in the end product incorporating the goods.
As a prototype, this product does not fall within the scope of the European Union directive on electromagnetic
compatibility and therefore may not meet the technical requirements of the directive.
Should this evaluation kit not meet the specifications indicated in the EVM User’s Guide, the kit may be returned
within 30 days from the date of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE
WARRANTY MADE BY SELLER TO BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED,
IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY
PARTICULAR PURPOSE.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user
indemnifies TI from all claims arising from the handling or use of the goods. Please be aware that the products
received may not be regulatory compliant or agency certified (FCC, UL, CE, etc.). Due to the open construction
of the product, it is the user’s responsibility to take any and all appropriate precautions with regard to electrostatic
discharge.
EXCEPT TO THE EXTENT OF THE INDEMNITY SET FORTH ABOVE, NEITHER PARTY SHALL BE LIABLE
TO THE OTHER FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
TI currently deals with a variety of customers for products, and therefore our arrangement with the user is not
exclusive.
TI assumes no liability for applications assistance, customer product design, software performance, or
infringement of patents or services described herein.
Please read the EVM User’s Guide and, specifically, the EVM Warnings and Restrictions notice in the EVM
User’s Guide prior to handling the product. This notice contains important safety information about temperatures
and voltages. For further safety concerns, please contact the TI application engineer.
Persons handling the product must have electronics training and observe good laboratory practice standards.
No license is granted under any patent right or other intellectual property right of TI covering or relating to any
machine, process, or combination in which such TI products or services might be or are used.
Mailing Address:
Texas Instruments
Post Office Box 655303
Dallas, Texas 75265
Copyright 2004, Texas Instruments Incorporated

EVM WARNINGS AND RESTRICTIONS
It is important to operate this EVM within the input voltage range of 6 VDC to 10 VDC and the
output voltage range of 3 VDC described in the EVM User’s Guide.
Exceeding the specified input range may cause unexpected operation and/or irreversible
damage to the EVM. If there are questions concerning the input range, please contact a TI
field representative prior to connecting the input power.
Applying loads outside of the specified output range may result in unintended operation and/or
possible permanent damage to the EVM. Please consult the EVM User’s Guide prior to
connecting any load to the EVM output. If there is uncertainty as to the load specification,
please contact a TI field representative.
During normal operation, some circuit components may have case temperatures greater than
40°C. The EVM is designed to operate properly with certain components above 40°C as long
as the input and output ranges are maintained. These components include but are not limited
to linear regulators, switching transistors, pass transistors, and current sense resistors. These
types of devices can be identified using the EVM schematic located in the EVM User’s Guide.
When placing measurement probes near these devices during operation, please be aware
that these devices may be very warm to the touch.
Mailing Address:
Texas Instruments
Post Office Box 655303
Dallas, Texas 75265
Copyright 2004, Texas Instruments Incorporated

How to Use This Manual
v
Preface
Read This First
About This Manual
This user’s guide describes the function and operation of the TLV320DAC26,
or simply DAC26, audio codec evaluation module. The manual helps users to
quickly set up the evaluation board and its accompanying software, so that
they can rapidly test and evaluate the DAC26. A complete circuit description,
schematic diagram, and bill of materials are included.
How to Use This Manual
This manual begins with an introductory chapter that describes the EVM and
what it can do. To set up the EVM and start testing quickly, read at least the
first two chapters. These two chapters introduce the board and how to set it
up. Later chapters go into more detail about the board design and how to ac-
cess its many features.
Information About Cautions and Warnings
This document may contain cautions and warnings.
This is an example of a caution statement.
A caution statement describes a situation that could potentially
damage your software or equipment.
This is an example of a warning statement.
A warning statement describes a situation that could potentially
cause harm to you.

Related Documentation From Texas Instruments
vi
The information in a caution or a warning is provided for your protection.
Please read each caution and warning carefully.
Related Documentation From Texas Instruments
To obtain a copy of any of the following TI documents, call the Texas
Instruments literature response center at (800) 477−8924 or the product
information center (PIC) at (972) 644−5580. When ordering, identify this user’s
guide by its title and literature number. Updated documents can also be
obtained through the TI Web site at www.ti.com.
Data Sheets: Literature Number:
TLV320DAC26 SLAS428
TAS1020B SLES025A
TPS767D318 SLVS209D
SN74LVC125A SCAS290M
If You Need Assistance
If you have questions about this or other Texas Instruments data converter
evaluation modules, send an e−mail to the data converter application team at
[email protected]. Include the product name in the subject heading.
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.
Trademarks
Windows is a registered trademark of Microsoft Corporation.
TouchTek 4 and MicroTouch are trademarks of 3M.

Contents
vii
Contents
1 Introduction 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1 Device Characteristics 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 EVM Block Diagram 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3 Analog Outputs/Inputs 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4 Power Requirements 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.5 Computer Requirements 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 Getting Started 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.1 Unpacking the EVM 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2 Default Configuration 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3 Quick Start 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 Operation 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1 Jumpers 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.1 Differential Microphone Input 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.2 MIC BIAS Selection 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.3 EEPROM A1 Select 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.4 Power Supply Selection 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.5 Power Supply Current Measurement 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.6 IOVDD Voltage Selection 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2 Switches 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2.1 SPI Selection 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2.2 I2S Selection 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2.3 MCLK Selection 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2.4 USB Reset 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3 I/O Connector and Signals 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.1 Analog Connectors 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.2 USB Interface Connector 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.3 External Power Connectors 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.4 External Audio Data (I2S) Connector 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.5 External SPI Connector 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.6 Analog Input Connector 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4 Circuit Description 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4.1 USB Microprocessor 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4.2 Power Supply 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4.3 Analog Outputs 3-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.5 Program Description 3-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.5.1 Register Reading Screen 3-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.5.2 DAC Configuration Screen 3-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.5.3 DAC Output Filters Screen 3-13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Contents
viii
4 Physical Description 4-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1 Component Locations 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2 Bill of Materials 4-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3 Schematics 4-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figures
1−1 DAC26 Evaluation Kit Block Diagram 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2−1 Default Software Screen 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−1 Register Reading Screen With Control Registers Reading 3-9. . . . . . . . . . . . . . . . . . . . . . . . . .
3−2 Register Reading Screen With Boost Filter Parameters 3-10. . . . . . . . . . . . . . . . . . . . . . . . . . .
3−3 DAC Configuration Screen 3-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−4 DAC Output Filter Screen 3-14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tables
2−1 Default Configuration Settings 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−1 Jumper/Function Reference 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−2 Switch Function Reference 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−3 Audio Connectors 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−4 USB Interface Connector 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−5 External Power Connectors 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−6 Audio Data Connector 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−7 External SPI Connector 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−8 Analog Input Connector 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1-1
Introduction
Introduction
The DAC26 is a low-power, high-performance audio band DAC with dual or
stereo output. The DAC26 has two digital interface buses that communicate
with a host processor: the SPI interface and the I2S interface. The SPI serial
interface is for a host processor to control the DAC26, and the DAC data is
communicated to the DAC26 over the I2S bus. The DAC26 accesses both of
these buses through the use of a USB microcontroller, which provides a way
to generate data for both buses from a PC running Windowsr98, Windows
2000, or Windows XP.
Topic Page
1.1 Device Characteristics 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 EVM Block Diagram 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3 Analog Outputs 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4 Power Requirements 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.5 Computer Requirements 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 1

Device Characteristics
1-2
1.1 Device Characteristics
The DAC26 is an audio band DAC with headphone/speaker amplifier. The
DAC26 has audio playback capability. Access to the audio DAC section of the
DAC26 is through an I2S interface. The DAC26 interfaces to the host controller
through a standard SPI serial interface.
1.2 EVM Block Diagram
A block diagram of the DAC26 evaluation kit is shown in Figure 1−1.
Figure 1−1.DAC26 Evaluation Kit Block Diagram
TAS1020B
(MCU and
USB Controller)
J10
4
5
3
3.3 V
VREG
12
J11
1211 I2S AUDIO
12
J12
1211 EXT SPI
USB
J9
6−12 VDC
SPI I2S
AUDIOANALOG
J6
HEADPHONE OUT
J7
OUT
J5
MIC IN
AUX
GND
J3
DAC26 MICIN
Onboard MK1
2I2CEEPROM Store
Firmware
for TAS1020B
6−10 VDC
2,5 mm
J8
Buffer
Buffer
SW1
1.8 V
Loudspeaker
J13
The digital control interface is through either the USB bus or an external SPI
bus. The onboard microprocessor can be disabled, allowing the external SPI
bus to control the DAC26.
Power supplies are derived from the USB bus or may be provided to the kit
through external connectors from an external user-supplied laboratory power
supply.

Analog Outputs
1-3
Introduction
1.3 Analog Outputs/Inputs
The audio output is accessed through connectors J6, J7, and/or terminal block
J13. To test the DAC26 sidetone function, the audio signal input can be from
either the onboard microphone MKI or an external microphone connected to
J5.
1.4 Power Requirements
The DAC26EVM can be powered from either the USB port or an external
6-VDC to 10-VDC power supply.
1.5 Computer Requirements
The DAC26EVM software is designed to run on a PC running Windows
platforms that support USB (Windows98SE, 2000, XP, etc).
Minimum requirements include:
-IBM-compatible Pentium PC or higher
-Windows98SE/2000/XP
-64-MByte RAM minimum
-20-MByte available hard disk space
-CD-ROM drive
-USB Port

1-4
THIS PAGE INTENTIONALLY LEFT BLANK

2-1
Getting Started
Getting Started
This chapter provides guidance for unpacking the EVM and setting it up for im-
mediate operation.
Topic Page
2.1 Unpacking the EVM 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2 Default Configuration 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3 Quick Start 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 2

Unpacking the EVM
2-2
2.1 Unpacking the EVM
When unpacking the DAC26EVM, make sure that the EVM kit includes the
following:
-DAC26EVM board, PWB 6444324
-CD-ROM, 6463159
If any of these components is missing, contact Texas Instruments for a
replacement.
2.2 Default Configuration
The DAC26EVM features a few, simple means of configuring its operation.
Table 2−1 shows the default settings for these items. After unpacking the
DAC26EVM, make sure that the board is initially configured as listed in the
table.
Table 2−1.Default Configuration Settings
Board Identifier Description Default Setting
JMP1 Differential MIC input Not installed
JMP2 MIC BIAS select 2 to 3
JMP3 A1 select for EEPROM Installed
JMP4 PWR select 1 to 2
JMP9 IOVDD selected as 3.3 V 1 to 2
SW1 Onboard
TAS1020B enable
Onboard I2S SW1_1 ON
SW1
Onboard
TAS1020B enable Onboard MCLK SW1_2 ON
Onboard SPI SW1_3 ON
USB reset SW1_4 ON
NOTE: JMP5 through JMP8 are installed by default. These jumpers can be removed and replaced
by current meters for evaluating or testing the corresponding power consumption.
2.3 Quick Start
After unpacking the DAC26EVM and verifying that the board is configured as
shown in Table 2−1, install the software.
Place the CD-ROM into the PC’s CD-ROM drive. Locate the Setup program
on the disk, and run it. The Setup program installs the DAC26EVM software
on the PC. Note that if the PC is running Windows2000 or XP, administrator
privileges are required to install the software. Follow the instructions that the
installer provides.
When the installation is complete, connect a USB cable from the PC to the
DAC26EVM. A message may appear that a Human Interface /Audio Device
has been connected. Once this connection has been made, launch the
DAC26EVM software on the PC.
The software should automatically find the DAC26EVM. When the board is
found, the screen shown in Figure 2−1 appears.

Quick Start
2-3
Getting Started
Figure 2−1.Default Software Screen

2-4
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3-1
Operation
Operation
This chapter describes each function of the DAC26 evaluation kit and how to
use the accompanying software to control and use the DAC26.
Topic Page
3.1 Jumpers 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2 Switches 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3 I/O Connectors and Signals 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4 Circuit Description 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.5 Program Description 3-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 3

Jumpers
3-2
3.1 Jumpers
Table 3−1 shows the function of each jumper on the EVM.
Table 3−1.Jumper/Function Reference
Reference
Designator Setting Function Factory Default Subsection
JMP1 1 to 2 Differential (MICIN and AUX) microphone
input (for sidetone only) Not installed 3.1.1
JMP2
1 to 2 MIC BIAS from fixed resistor
2 to 3
3.1.2
JMP2
2 to 3 MIC BIAS from DAC26
2 to 3
3.1.2
JMP3 1 to 2 A1 select for EEPROM Installed 3.1.3
JMP4
1 to 2 PWR select: USB powered
1 to 2
3.1.4
JMP4
2 to 3 PWR select: External power supply
1 to 2
3.1.4
JMP5 − JMP8
Removed Power is not provided to DAC26
Installed
3.1.5
JMP5 − JMP8
Installed Power is provided to DAC26
Installed
3.1.5
JMP9
1 to 2 DAC26 uses 3.3-V IOVDD
1 to 2
3.1.6
JMP9
2 to 3 DAC26 uses 1.8-V IOVDD
1 to 2
3.1.6
3.1.1 Differential Microphone Input
The microphone signal can be input to the DAC26 through the MICIN or AUX,
if the signal is single ended. In single-ended mode, JMP1 should be removed.
The microphone signal, if differential, can be connected to the DAC26 through
J5 and to the DAC26 MICIN and AUX pins. In differential mode, JMP1 should
be installed.
3.1.2 MIC BIAS Selection
JMP2 selects the microphone bias to come from the DAC26 itself or from an
external resistor, R11, which is not installed on the DAC26EVM board. If an
external bias is needed, the appropriate size resistor can be soldered into the
R11 location on the board and JMP2 set to connect between positions 1 and
2. If MIC BIAS is not required, do not install the jumper top for JMP2 in any
position.
3.1.3 EEPROM A1 Select
The DAC26EVM loads its firmware from an onboard EEPROM. In order to use
the firmware in this EEPROM, its address A2, A1, A0 should be 000b. JMP3
is used to pull the A1 line low so that the EEPROM is selected. When A1 is not
low, the EEPROM is not able to interface to the onboard TAS1020B processor.
This jumper can be removed when firmware updates are to be made.
3.1.4 Power Supply Selection
The DAC26EVM can be powered from the USB port directly, or an external
power supply can be provided through J9 or J10. JMP4 selects between the
USB and external power sources.

Switches
3-3
Operation
3.1.5 Power Supply Current Measurement
Four jumpers are on the front of the four power supply pins of the DAC26. The
jumpers can be replaced by current meters that measure and monitor the
currents in the corresponding power supply pins. See the note accompanying
Table 2−1.
3.1.6 IOVDD Voltage Selection
One of the features of the DAC26 is the flexibility of the digital IO power supply
with a range from 1.1 V to 3.6 V. To evaluate this feature, the EVM has the
JMP9 jumper for IOVDD selection. If JMP9 is at 1 to 2 position, IOVDD is 3.3
V; if JMP9 is at 2 to 3, IOVDD is 1.8 V: and without JMP9, an extra power supply
(1.1 V to 3. 6 V) can be connected to IOVDD.
3.2 Switches
The onboard SW1 switch gives users the option to select SPI and I2S as well
as MCLK signal resources. Table 3−2 shows the function of the switch.
Table 3−2.Switch Function Reference
Reference
Designator Setting Function Factory Default Subsection
SW1-1
ON Onboard I2S selected
ON
3.2.2
SW1-1
OFF External I2S selected
ON
3.2.2
SW1-2
ON Onboard MCLK selected
ON
3.2.3
SW1
SW1-2
OFF External MCLK selected
ON
3.2.3
SW1
SW1-3
ON Onboard SPI selected
ON
3.2.1
SW1-3
OFF External SPI selected
ON
3.2.1
SW1-4
ON USB Reset connected to DAC26
ON
3.2.4
SW1-4
OFF USB Reset not connected to DAC26
ON
3.2.4
3.2.1 SPI Selection
The SPI bus on the DAC26 provides the main interface between a
host-processor and the DAC26 device. The onboard TAS1020B plays the role
of the host processor, if SW1-3 is set to the ON position. If an external
processor or SPI device is used, set the SW1-3 to the OFF position so as to
disable the onboard SPI interface to the TAS1020B and open the DAC26 SPI
port to the external SPI bus.
3.2.2 I2S Selection
The I2S bus on the DAC26 can interface with the onboard host processor, the
TAS1020B USB controller, or with other offboard external I2S processor or
devices. When SW1-1 is set to ON, the manufacturer default, the DAC26 I2S
is connected to the TAS1020B’s I2S. Otherwise, if SW1-1 is shifted to OFF, the
buffer between the onboard I2S port is disabled so that an external I2S can
communicate with the DAC26 I2S port.

I/O Connector and Signals
3-4
3.2.3 MCLK Selection
The DAC26 requires a proper MCLK for basic audio DAC functions. The
TAS1020B onboard processor generates an 11.2896-MHz frequency to
provide the MCLK. If an external MCLK is preferred, SW1-2 should be turned
off.
3.2.4 USB Reset
A reset signal output from the onboard TAS1020B processor can be used to
reset the the DAC26 whenever the TAS1020B is resetting. SW1−4 is used to
enable/disable the connection. By default, the connection is enabled. If the
processing is not active, the connection to the DAC26 should be disabled by
turning off SW1−4.
3.3 I/O Connector and Signals
The various connectors on the DAC26EVM are described in this section.
3.3.1 Analog Connectors
The DAC26 analog inputs and outputs are routed through these stereo
(TIP/RING/SLEEVE) 3,5-mm jacks. Note the polarity of the channel
assignments for these connectors.
Table 3−3.Audio Connectors
Reference
Designator Name Description
J5 Mic In Microphone input
-tip = mic bias voltage (and MIC input−, if different)
-ring = mic input+
-sleeve = ground
J6 Headphone
Out Stereo headphone audio outputs
-tip = left channel
-ring = right channel
-sleeve = virtual ground
J7 Line Out Stereo headphone output with ac coupling
-tip = left channel
-ring = right channel
-sleeve = ground
J13 Loudspeaker When the DAC26 output drive is in high power mode, an 8-Ωloudspeaker can
be connected to J13.